tag:theconversation.com,2011:/id/topics/fasting-diet-5633/articlesFasting diet – The Conversation2023-10-10T21:43:33Ztag:theconversation.com,2011:article/2077232023-10-10T21:43:33Z2023-10-10T21:43:33ZWhat is the OMAD diet? Is one meal a day actually good for weight loss? And is it safe?<figure><img src="https://images.theconversation.com/files/551627/original/file-20231003-26-odr3p8.jpg?ixlib=rb-1.1.0&rect=152%2C26%2C5838%2C3449&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/female-bare-feet-weight-scale-bathroom-785794792">Shutterstock</a></span></figcaption></figure><p>What do British Prime Minister <a href="https://www.sciencefocus.com/the-human-body/one-meal-a-day-diet-omad">Rishi Sunak</a> and singer <a href="https://theconversation.com/one-meal-a-day-diet-popular-with-celebrities-could-do-more-harm-than-good-heres-why-203086">Bruce Springsteen</a> have in common?</p>
<p>They’re among an ever-growing group of public figures touting the benefits of eating just one meal a day.</p>
<p>As a result, the one meal a day (OMAD) diet is the latest attention-grabbing weight loss trend. Advocates claim it leads to fast, long-term weight loss success and better health, including delaying the ageing process. </p>
<p>Like most weight-loss programs, the OMAD diet makes big and bold promises. Here’s what you need to know about eating one meal a day and what it means for weight loss.</p>
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Read more:
<a href="https://theconversation.com/whats-the-weight-set-point-and-why-does-it-make-it-so-hard-to-keep-weight-off-195724">What's the 'weight set point', and why does it make it so hard to keep weight off?</a>
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<h2>The OMAD diet explained</h2>
<p>Essentially, the OMAD diet is a type of intermittent fasting, where you fast for 23 hours and consume all your daily calories in one meal eaten within one hour.</p>
<p>The OMAD diet rules are presented as simple and easy to follow:</p>
<ol>
<li><p>You can eat whatever you want, provided it fits on a standard dinner plate, with no calorie restrictions or nutritional guidelines to follow. </p></li>
<li><p>You can drink calorie-free drinks throughout the day (water, black tea and coffee). </p></li>
<li><p>You must follow a consistent meal schedule, eating your one meal around the same time each day.</p></li>
</ol>
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<img alt="Plate of chicken and veggies, next to a cup of dried fruit" src="https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551622/original/file-20231003-25-n2lo07.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The one meal a day diet significantly restricts your calorie intake.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/ZjEeMnDiq00">Ella Olsson/Unsplash</a></span>
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<p>Along with creating a calorie deficit, resulting in weight loss, advocates believe the OMAD diet’s extended fasting period <a href="https://www.frontiersin.org/articles/10.3389/fphys.2021.771944/full">leads to physiological changes</a> in the body that promote better health, including boosting your metabolism by triggering a process called ketosis, where your body burns stored fat for energy instead of glucose. </p>
<h2>What does the evidence say?</h2>
<p>Unfortunately, research into the OMAD diet is limited. Most studies have examined its impact on <a href="https://www.cell.com/cell-metabolism/pdf/S1550-4131(18)30512-6.pdf">animals</a>, and the <a href="https://pubmed.ncbi.nlm.nih.gov/35087416/">primary study</a> with humans involved 11 lean, young people following the OMAD diet for a mere 11 days.</p>
<p>Claims about the OMAD diet typically rely on research into intermittent fasting, rather than on the OMAD diet itself. There is <a href="https://www.cfp.ca/content/66/2/117.short">evidence</a> backing the efficacy of intermittent fasting to achieve weight loss. However, <a href="https://www.nature.com/articles/s41574-022-00638-x">most studies</a> have focused on short-term results only, typically considering the results achieved across 12 weeks or less.</p>
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Read more:
<a href="https://theconversation.com/does-it-matter-what-time-of-day-i-eat-and-can-intermittent-fasting-improve-my-health-heres-what-the-science-says-203762">Does it matter what time of day I eat? And can intermittent fasting improve my health? Here's what the science says</a>
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<p>One <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2114833">longer-term study from 2022</a> randomly assigned 139 patients with obesity to either a calorie-restricted diet with time-restricted eating between 8am and 4pm daily, or to a diet with daily calorie restriction alone for 12 months.</p>
<p>After 12 months, both groups had lost around the same weight and experienced similar changes in body fat, blood sugar, cholesterol and blood pressure. This indicates long-term weight loss achieved with intermittent fasting is not superior and on a par with that achieved by traditional dieting approaches (daily calorie restriction).</p>
<h2>So what are the problems with the OMAD diet?</h2>
<p><strong>1. It can cause nutritional deficiencies and health issues.</strong></p>
<p>The OMAD diet’s lack of nutritional guidance on what to eat for that one meal a day raises many red flags. </p>
<p>The meals we eat every day should include a source of protein balanced with wholegrain carbs, vegetables, fruits, protein and good fats to support <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071223/">optimum health, disease prevention and weight management</a>.</p>
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<img alt="Woman shops for groceries" src="https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551625/original/file-20231003-15-4yrdir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">We’re likely to miss out on key nutrients if we eat one meal a day.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/woman-in-green-shirt-looking-at-her-grocery-list-8422685/">Kampus Production/Pexels</a></span>
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<p>Not eating a balanced diet will result in nutritional deficiencies that can result in poor immune function, fatigue and a decrease in bone density, leading to osteoporosis. </p>
<p>Fasting for 23 hours a day is also likely to lead to extreme feelings of hunger and uncontrollable cravings, which may mean you consistently eat foods that are not good for you when it’s time to eat. </p>
<p><strong>2. It’s unlikely to be sustainable.</strong></p>
<p>You might be able to stick with the OMAD diet initially, but it will wear thin over time. </p>
<p>Extreme diets – especially ones prescribing extended periods of fasting – aren’t enjoyable, leading to feelings of deprivation and social isolation during meal times. It’s hard enough to refuse a piece of office birthday cake at the best of times, imagine how this would feel when you haven’t eaten for 23 hours!</p>
<p>Restrictive eating can also lead to an unhealthy relationship with food, making it even harder to achieve and maintain a healthy weight. </p>
<p><strong>3. Quick fixes don’t work.</strong></p>
<p>Like other popular intermittent fasting methods, the OMAD diet appeals because it’s easy to digest, and the results appear fast. </p>
<p>But the OMAD diet is just another fancy way of cutting calories to achieve a quick drop on the scales. </p>
<p>As your weight falls, things will quickly go downhill when your <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766925/">body activates its defence mechanisms</a> to defend your weight loss. In fact, it will regain weight – a response that stems from our hunter-gatherer ancestors’ need to survive periods of deprivation when food was scarce.</p>
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Read more:
<a href="https://theconversation.com/is-it-true-the-faster-you-lose-weight-the-quicker-it-comes-back-heres-what-we-know-about-slow-and-fast-weight-loss-198301">Is it true the faster you lose weight the quicker it comes back? Here's what we know about slow and fast weight loss</a>
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<h2>The bottom line</h2>
<p>Despite the hype, the OMAD diet is unsustainable, and it doesn’t result in better weight-loss outcomes than its predecessors. Our old habits creep back in and we find ourselves fighting a cascade of physiological changes to ensure we regain the weight we lost.</p>
<p>Successfully losing weight long-term comes down to:</p>
<ul>
<li><p>losing weight in small manageable chunks you can sustain, specifically periods of weight loss, followed by periods of weight maintenance, and so on, until you achieve your goal weight</p></li>
<li><p>making gradual changes to your lifestyle to ensure you form habits that last a lifetime.</p></li>
</ul>
<p><em>At the Boden Group, Charles Perkins Centre, we are studying the science of obesity and running clinical trials for weight loss. You can <a href="https://redcap.sydney.edu.au/surveys/?s=RKTXPPPHKY">register here</a> to express your interest.</em></p><img src="https://counter.theconversation.com/content/207723/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Nick Fuller works for the University of Sydney and has received external funding for projects relating to the treatment of overweight and obesity. He is the author and founder of the Interval Weight Loss program.</span></em></p>Like most weight-loss programs, the OMAD diet makes bold promises – and comes with risks.Nick Fuller, Charles Perkins Centre Research Program Leader, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1663932021-09-28T11:56:22Z2021-09-28T11:56:22ZCan healthy people who eat right and exercise skip the COVID-19 vaccine? A research scientist and fitness enthusiast explains why the answer is no<figure><img src="https://images.theconversation.com/files/422695/original/file-20210922-25-11lek97.jpg?ixlib=rb-1.1.0&rect=16%2C24%2C5439%2C3612&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Several thousand protestors opposed to the COVID-19 vaccine march through the streets of midtown Manhattan in New York on Sept. 18, 2021. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/several-thousand-protestors-opposed-to-the-covid-19-vaccine-news-photo/1341164693?adppopup=true">Andrew Lichtenstein/Corbis News via Getty Images</a></span></figcaption></figure><p>I’m a fitness enthusiast. I also adhere to a nutrient-dense, “clean” eating program, which means I minimize my sugar intake and eat a lot of whole foods for the purpose of optimizing my health. </p>
<p>You might wonder how effective such a diet and exercise plan would be in the fight against COVID-19, since some <a href="https://www.washingtonpost.com/technology/2021/09/12/wellness-influencers-vaccine-misinformation/">have suggested</a> – without supporting evidence – that vaccination may be unnecessary if a detailed wellness lifestyle is closely followed. </p>
<p>As a <a href="https://scholar.google.com/scholar?hl=en&as_sdt=0%2C43&q=Bloomer+and+memphis&btnG=">research scientist</a> who has studied nutrition for close to 20 years, I have watched the wellness community’s response to the COVID-19 vaccines with great interest. While eating right can <a href="https://doi.org/10.3390/nu12061562">favorably impact the immune system</a>, it is not reasonable to expect that nutrition alone will defend against a potentially life-threatening virus. </p>
<h2>My experience with nutrition science</h2>
<p>My lab group at the <a href="https://www.memphis.edu/healthsciences/">University of Memphis</a> studies the effect of food and isolated nutrients on human health. In January 2009, we conducted an initial study of a stringent vegan diet. We enrolled 43 men and women who were allowed to eat as much plant-based food as desired, but drank only water, for 21 days. </p>
<p>The results demonstrated improvements <a href="https://doi.org/10.1186/1476-511X-9-94">in many variables</a> related to cardio-metabolic health, such as blood cholesterol, blood pressure, insulin and C-reactive protein – a protein that increases in response to inflammation. We have <a href="https://pubmed.ncbi.nlm.nih.gov/?term=bloomer+and+daniel+fast">since completed</a> multiple human and animal nutrition studies using this dietary program. </p>
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<img alt="A woman eating a healthy salad." src="https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/422240/original/file-20210920-19-log1mt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Diet improvements may reduce or eliminate the need for some medications, but a clean diet cannot completely protect you from COVID-19.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/woman-eating-salad-royalty-free-image/912617718?adppopup=true">Tara Moore via Getty Images</a></span>
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<p>My lab’s research has resulted in some 200 peer-reviewed scientific manuscripts and book chapters specific to <a href="https://umwa.memphis.edu/fcv/viewprofile.php?uuid=rbloomer">nutrients and exercise</a>, and the interaction between these two variables. The results of our work, as well as that of other scientists, clearly demonstrate the power of food to favorably impact health.</p>
<p>For many individuals, a positive change in eating habits results in such an improvement in clinically relevant measures like <a href="https://doi.org/10.1186/1476-511X-9-94">blood cholesterol</a> <a href="https://doi.org/10.3390/ijerph17072557">and glucose</a> that doctors can sometimes reduce or eliminate certain medications used to treat high cholesterol and diabetes. In other cases, these measures improve but the patient still requires the use of medications to control their disease. This tells us that in some situations, a great nutrition program is simply not enough to overcome the body’s challenges.</p>
<h2>Nutrition and other wellness approaches do matter</h2>
<p>Although certain <a href="https://doi.org/10.3389/fphar.2020.01189">natural products</a> have been discussed as treatments for COVID-19, little emphasis has been placed on whole food nutrition as a protective measure. I think this is unfortunate, and I believe strengthening our immune system with the goal of battling COVID-19 and other viral infections is of great importance. And the <a href="https://theconversation.com/good-nutrition-can-contribute-to-keeping-covid-19-and-other-diseases-away-145086">evidence tells us</a> that a <a href="https://doi.org/10.3390/nu12061562">nutrient dense diet</a>, <a href="http://dx.doi.org/10.1136/bjsports-2021-104080">regular exercise</a> and <a href="https://doi.org/10.1007/s00424-011-1044-0">adequate sleep</a> can all contribute to optimal immune function. </p>
<p>Regarding nutritional intake, a <a href="https://doi.org/10.1136/bmjnph-2021-000272">recently published study</a> using a sample of health care workers who contracted COVID-19 noted that those who followed a plant-based or pescatarian diet had 73% and 59% lower odds of moderate to severe COVID-19, respectively, compared to those who did not follow those diets. Although interesting, it’s important to remember that these findings represent an association rather than a causal effect. </p>
<p>While people can use nutrition to help shore up their immune system against COVID-19, diet is only one important consideration. Other <a href="https://doi.org/10.3945/an.115.010207">variables matter</a> a great deal too, including <a href="https://pubmed.ncbi.nlm.nih.gov/29306937/">stress management</a>, <a href="https://doi.org/10.3389/fimmu.2020.570122">nutritional supplements</a> and <a href="https://doi.org/10.1016/S0140-6736(20)31142-9">physical distancing and mask-wearing</a>.</p>
<p>But to be clear, all of those elements should be considered tools in the toolbox to help combat COVID-19 – not a replacement for potentially life-saving vaccines. </p>
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<img alt="A teenage boy at a clinic getting a COVID-19 shot." src="https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/422243/original/file-20210920-25-4sj241.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Charles Muro, age 13, receives a COVID-19 shot at a mass vaccination center in Hartford, Connecticut. Without the vaccine, even young people in good health are not fully protected from the virus.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/charles-muro-age-13-is-inoculated-by-nurse-karen-pagliaro-news-photo/1232871480?adppopup=true">Joseph Prezioso/AFP via Getty Images</a></span>
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<h2>Vaccines are not perfect, but they save lives</h2>
<p>I find it interesting that nearly all parents understand the importance of having their kids <a href="https://abcnews.go.com/US/vaccine-mandates-place-attend-school-us/story?id=80046650">vaccinated against serious illnesses</a> like mumps, measles and varicella. They do not expect that certain foods, or a nurturing environment, will do the job of a vaccine. </p>
<p>Yet, when it comes to COVID-19, this thought process is abandoned by <a href="https://www.washingtonpost.com/technology/2021/09/12/wellness-influencers-vaccine-misinformation/">some who believe</a> that a healthy lifestyle will substitute for the vaccine, without seriously considering <a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">what the vaccine actually does to provide protection</a> against the virus – something that a healthy lifestyle alone simply cannot do. </p>
<p>When contemplating whether to receive the COVID-19 vaccine, consider the following: All medications have risks, including things as <a href="https://www.huffingtonpost.co.uk/entry/daily-aspirin-causes-more-than-3000-deaths-per-year-scientists-warn_uk_593fb481e4b0b13f2c6daa10">seemingly benign as aspirin</a>. <a href="https://doi.org/10.1177/0024363918816683">Hormonal contraception</a> – something used by millions of women every month – is thought to cause an estimated 300-400 deaths annually in the U.S. The same is true for <a href="https://www.huffpost.com/entry/what-would-wendy-davis-do_b_3672484">cosmetic surgery</a>, <a href="https://doi.org/10.1007/s00266-020-02027-z">Botox injections</a> and other elective procedures. </p>
<p>Many people are willing to accept the low risks in those cases, but not with those involving <a href="https://theconversation.com/what-does-full-fda-approval-of-a-vaccine-do-if-its-already-authorized-for-emergency-use-165654">the COVID-19 vaccines</a> – despite the fact that the risk of <a href="https://www.theguardian.com/world/2021/aug/27/blood-clot-risk-greater-after-covid-infection-than-after-vaccination">serious complications or death from COVID-19</a> far outweighs the low risk of serious <a href="https://theconversation.com/new-covid-19-vaccine-warnings-dont-mean-its-unsafe-they-mean-the-system-to-report-side-effects-is-working-164455">adverse events</a> from the vaccines. </p>
<p>No lifestyle approach, including strict adherence to a holistic, nutrient-dense diet – vegan, plant-forward or otherwise – will confer total protection against COVID-19. The vaccines <a href="https://theconversation.com/medicine-is-an-imperfect-science-but-you-can-still-trust-its-process-166811">aren’t perfect</a> either; <a href="https://theconversation.com/what-is-a-breakthrough-infection-6-questions-answered-about-catching-covid-19-after-vaccination-164909">breakthrough infections</a> do occur in some cases, though the vaccines <a href="https://www.wsj.com/articles/breakthrough-cases-covid-19-delta-variant-11627596643">continue to provide robust protection</a> against <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7037e1.htm?s_cid=mm7037e1_w#T1_down">severe illness and death</a>. </p>
<p>I encourage people to do all they can to improve the health and functioning of their immune system, naturally. Then, seriously consider what additional protection would be gained from vaccination against COVID-19. When people make decisions based on the latest science – which is always evolving – rather than on emotions and misinformation, the decision should become much clearer.</p><img src="https://counter.theconversation.com/content/166393/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard J. Bloomer has received research support and has served as a consultant to a variety of dietary ingredient and supplement companies over the past 20 years. </span></em></p>A growing body of research shows that nutrition, sleep, exercise and a host of other lifestyle choices can help optimize the immune system. But they are no substitute for life-saving vaccines.Richard Bloomer, Dean of the College of Health Sciences, University of MemphisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1200802019-08-27T20:12:51Z2019-08-27T20:12:51ZThe science behind diet trends like mono, charcoal detox, Noom and Fast800<figure><img src="https://images.theconversation.com/files/289561/original/file-20190827-184234-oxa0m3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7348%2C4912&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mono dieters restrict their intake to one food or food group per day.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/247502347?src=-1-90&size=huge_jpg">Alliance Images/Shutterstock</a></span></figcaption></figure><p>Every year a new batch of diets become trendy. In the past, the <a href="https://theconversation.com/blood-type-pioppi-gluten-free-and-mediterranean-which-popular-diets-are-fads-104867">blood group</a>, <a href="https://theconversation.com/do-ketogenic-diets-help-you-lose-weight-81810">ketogenic</a>, <a href="https://theconversation.com/blood-type-pioppi-gluten-free-and-mediterranean-which-popular-diets-are-fads-104867">Pioppi and gluten-free</a> diets were among the most popular. These have made way for the mono diet, charcoal detox, Noom, time-restricted feeding and Fast800. </p>
<p>So what are these new diets and is there any scientific evidence to support them? </p>
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Read more:
<a href="https://theconversation.com/health-check-six-tips-for-losing-weight-without-fad-diets-52496">Health Check: six tips for losing weight without fad diets</a>
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<h2>1. Mono diet</h2>
<p>The <a href="https://en.wikipedia.org/wiki/Monotrophic_diet">monotrophic or mono diet</a> limits food intake to just one food group such as meat or fruit, or one individual food like potato or chicken, each day. </p>
<p>The mono diet has no scientific basis and no research has been done on it. It’s definitely a fad and should not be followed.</p>
<p>It leads to weight loss because your food intake is so limited (one food per day) that you get sick of that food very quickly and so automatically achieve a reduced kilojoule intake. </p>
<p>If you ate three apples at each main meal and had another three as between-meal snacks then your total kilojoule intake from the 12 apples would be about 4,000 kilojoules (950 calories). </p>
<p>The mono diet is nutritionally inadequate. The nutrients most deficient will depend on the individual foods consumed, but if you follow the mono diet long term, you would eventually develop vitamin and mineral deficiencies.</p>
<h2>2. Charcoal detox</h2>
<p>The charcoal detox diet claims to help people lose weight by “detoxing” them. It involves periods of fasting and consumption of tea or juice drinks that contain charcoal. </p>
<p>It is definitely <em>not</em> recommended. </p>
<p>Medical professionals use <a href="https://www.ncbi.nlm.nih.gov/books/NBK482294/">activated charcoal</a> to treat patients who have been poisoned or have overdosed on <a href="https://www.ncbi.nlm.nih.gov/pubmed/3766051">specific medications</a>. Charcoal can bind to some compounds and remove them from the body. </p>
<p>There is no scientific evidence to support the use of charcoal as a weight loss strategy. </p>
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<img alt="" src="https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289564/original/file-20190827-184207-14mp4xl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Avoid the charcoal detox diet.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/699336109?src=-1-0&size=medium_jpg">Andasea/Shutterstock</a></span>
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Read more:
<a href="https://theconversation.com/five-supplements-that-claim-to-speed-up-weight-loss-and-what-the-science-says-89856">Five supplements that claim to speed up weight loss – and what the science says</a>
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<p>Charcoal detox plans also include dietary restrictions or fasts, so people might lose weight because they’re consuming fewer kilojoules. </p>
<p>Charcoal is not selective. It can bind to some medications and nutrients, as well as toxic substances, so there is the potential for charcoal to trigger nutrient deficiencies and/or make some medications less effective. </p>
<p>Side-effects of using charcoal <a href="https://www.ncbi.nlm.nih.gov/pubmed/10584586">include nausea and constipation</a>.</p>
<h2>3. Noom diet</h2>
<p>The Noom diet isn’t actually a diet at all. It is a <a href="https://www.ncbi.nlm.nih.gov/pubmed/27819345">smartphone app called Noom Coach</a> that focuses on behaviour change techniques to assist with weight loss. It allows users to monitor their eating and physical activity, and provides support and feedback. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/xpGKfFJZrA","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>The Noom diet does not provide a diet plan, but it gets users to record within the app, all foods and drinks consumed. It then uses a traffic light system (red, yellow, green) to indicate how healthy the foods are. </p>
<p>One advantage of Noom is that is doesn’t eliminate any foods or food groups, and it encourages healthy lifestyle behaviour change to assist with weight loss. </p>
<p>A disadvantage is that while you can download the app for a free short-term trial, membership is <a href="https://web.noom.com/support/support-question-topic/my-account/2018/03/what-are-my-purchase-options/">about A$50 per month for four months</a>. And additional services cost extra. So consider whether this approach suits your budget.</p>
<p>One study has examined the app’s effectiveness. <a href="https://www.ncbi.nlm.nih.gov/pubmed/27819345">In a cohort of 35,921 Noom app users over 18 months</a>, almost 78% reported a reduction in body weight. About 23% of these people reported losing more than 10% of their body weight. </p>
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Read more:
<a href="https://theconversation.com/health-check-should-you-weigh-yourself-regularly-92177">Health Check: should you weigh yourself regularly?</a>
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<p>Although the data are observational and don’t compare Noom app users to a control group, the results are promising. </p>
<p>In other weight-loss interventions in adults at risk of developing type 2 diabetes, researchers found losing 5-10% body weight and being active for about 30 minutes a day <a href="https://www.ncbi.nlm.nih.gov/pubmed/22020084">lowered the risk of developing type 2 diabetes by more than 50%</a>.</p>
<h2>4. Time-restricted feeding</h2>
<p>Time-restricted feeding is a type of intermittent fast that involves restricting the time of day that you are “allowed” to eat. This typically means eating in a window lasting <a href="https://www.ncbi.nlm.nih.gov/pubmed/27304506">four to ten hours</a>. </p>
<p>While energy-restriction during this period is not a specific recommendation, it happens as a consequence of eating only during a shorter period of time than usual. </p>
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<img alt="" src="https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289568/original/file-20190827-184252-16v3nre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">It’s unclear whether weight loss results from changes in the body after you fast, or if it’s just because you can’t eat as much in a short period of time.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1278900526?src=-1-49&size=medium_jpg">Best_nj/Shutterstock</a></span>
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<p>The difference between time-restricted feeding compared to other intermittent fasting strategies is that recent research suggests <a href="https://www.ncbi.nlm.nih.gov/pubmed/31023390">some metabolic benefits are initiated</a> following a fasting period that lasts for 16 hours, as opposed to a typical overnight fast of ten to 12 hours. </p>
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Read more:
<a href="https://theconversation.com/health-check-whats-the-best-diet-for-weight-loss-21557">Health Check: what's the best diet for weight loss?</a>
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<p>Researchers have reported <a href="https://www.ncbi.nlm.nih.gov/pubmed/31023390">some promising effects on the amount of body fat, insulin sensitivity and blood cholesterol</a> with time-restricted feeding windows, although some studies have reported benefits for weight <a href="https://www.ncbi.nlm.nih.gov/pubmed/29951594">but not for fat mass, blood cholesterol</a> or markers of type 2 diabetes risk. </p>
<p>Further research is required to determine whether any health effects of time-restricted feeding are <a href="https://www.ncbi.nlm.nih.gov/pubmed/31023390">due to regular 16-hour fasting periods</a>, or simply because eating over a small time window reduces energy intake. </p>
<p>If this approach helps you get started on a healthy lifestyle and your GP gives you the all clear, then try it. You will need to follow up with some permanent changes to your lifestyle so your food and physical activity patterns are improved in the long term.</p>
<h2>5. Fast800</h2>
<p>The Fast800 diet by <a href="https://en.wikipedia.org/wiki/Michael_Mosley_(broadcaster)">Dr Michael Mosley</a> encourages a daily intake of just 800 calories (about 3,350 kilojoules) during the initial intensive phase of the <a href="https://thebloodsugardiet.com/">Blood Sugar Diet</a>. </p>
<p>This lasts for up to eight weeks and is supposed to help you rapidly lose weight and improve your blood sugar levels. You can buy the book for about A$20 or pay A$175 for a 12-week online program that says it includes a personal assessment, recipes, physical and mindfulness exercises, tools, access to experts, an online community, information for your doctor and advice for long-term healthy living. </p>
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<a href="https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289571/original/file-20190827-184229-1nfgbs2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Michael Mosley’s diet program is based on a very low daily energy intake.</span>
<span class="attribution"><a class="source" href="https://thefast800.com/">Screenshot of https://thefast800.com/</a></span>
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<p>Two recent studies provide some evidence that supports these claims: the <a href="https://www.ncbi.nlm.nih.gov/pubmed/29221645">DiRECT</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/30257983">DROPLET</a> trials. </p>
<p>In these studies, GPs prescribed patients who were obese and/or had type 2 diabetes an initial diet of 800 calories, using formulated meal replacements. This initial phase was followed by a gradual reintroduction of food. Participants also received structured support to help them maintain the weight loss. </p>
<p>Both studies compared the intervention to a control group who received either usual care or treatment using best practice guidelines. </p>
<p>They found participants in the 800 calorie groups lost more weight and more of the adults with type 2 diabetes achieved remission than the control groups. </p>
<p>This is what you would expect, given the intervention was very intensive and included a very low total daily energy intake. </p>
<p>But the low energy intake can make the Fast800 difficult to stick to. It can also be challenging to get enough nutrients, so protocols need to be carefully followed and any recommended nutrient supplements taken. </p>
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Read more:
<a href="https://theconversation.com/what-are-fasting-diets-and-do-they-help-you-lose-weight-76644">What are 'fasting' diets and do they help you lose weight?</a>
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<p>Fast800 is not suitable for people with a history of eating disorders or health conditions such as liver disease. So if you’re considering it, talk to your GP. </p>
<p>When it comes to weight loss, there are no magic tricks that guarantee success. Have a health check up with your GP, focus on making healthy lifestyle changes and if you need more support, ask to be referred to an <a href="https://daa.asn.au/find-an-apd/">accredited practising dietitian</a>.</p>
<p><em>If you would like to learn more about weight loss, you can enrol in our free online course <a href="https://www.edx.org/course/the-science-of-weight-loss-dispelling-diet-myths-2">The Science of Weight Loss – Dispelling Diet Myths</a>.</em></p><img src="https://counter.theconversation.com/content/120080/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research and Gladys M Brawn Research Fellow. She has received research grants from NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation, Rijk Zwaan Australia and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and the Heart Foundation evidence reviews on meat and dietary patterns.</span></em></p><p class="fine-print"><em><span>Lee Ashton is affiliated with the Priority Research Centre for Physical Activity and Nutrition at the University of Newcastle, NSW, Australia.</span></em></p><p class="fine-print"><em><span>Rebecca Williams is affiliated with the Priority Research Centre for Physical Activity and Nutrition at the University of Newcastle, NSW, Australia. </span></em></p>Diets like mono, charcoal detox, Noom, time-restricted feeding and Fast800 are growing in popularity. Here’s what the evidence says about them.Clare Collins, Professor in Nutrition and Dietetics, University of NewcastleLee Ashton, Postdoctoral research fellow, University of NewcastleRebecca Williams, Postdoctoral Researcher, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/766442017-05-08T03:39:18Z2017-05-08T03:39:18ZWhat are ‘fasting’ diets and do they help you lose weight?<figure><img src="https://images.theconversation.com/files/168260/original/file-20170508-7677-175jv54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are many types of "fasting" diets. But are they any better than restricting your energy intake the old fashioned way?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/344331644?src=OA2xswyElecJxS-y2G-M6w-1-26&size=medium_jpg">from www.shutterstock.com</a></span></figcaption></figure><p>Trying to lose weight is hard work. You need to plan meals and snacks, and make a big effort to <a href="https://theconversation.com/health-check-six-tips-for-losing-weight-without-fad-diets-52496">avoid situations that trigger more eating and drinking</a> than you’d planned. Dieting can also be very antisocial. But what if you could speed up weight loss, spend less time “dieting”, with the “promise” of better results? This is where “fasting” diets come in.</p>
<h2>What is a ‘fasting’ diet?</h2>
<p>Intermittent fasting is the broad name for diets when you fast to some degree on some, but not all, days of the week; you eat normally on the other days. </p>
<p>On “fast” days, the kilojoule (energy) restriction is severe, at about 25% of what you would normally eat. This is only 2,000 to 3,000 kilojoules a day. An average person needs around <a href="http://www.8700.com.au/">8,700 kilojoules</a> a day (depending on body size and activity level) to maintain their current body weight. </p>
<p>To lose between one quarter and half a kilogram a week you would need to <a href="https://theconversation.com/health-check-ten-ways-to-save-2-000-kilojoules-and-drop-a-clothes-size-37039">reduce your energy intake by 2,000 kilojoules a day</a>. Over a whole week, this is equivalent to cutting back total energy intake by 14,000 kilojoules. Fasting diets compress this 14,000 kilojoule reduction into fewer days of dieting. In practical terms, this means that you reduce your intake by so much on a couple of days, you do not to be so strict on the other days.</p>
<p>Depending on the type of “fasting” diet, you focus all your weight loss efforts into sticking to the severe restriction for either two days a week (as in the <a href="https://en.wikipedia.org/wiki/5:2_diet">5:2 diet</a>) or every second day (for three to four days days a week), as in <a href="https://en.wikipedia.org/wiki/Intermittent_fasting">alternate-day fasting</a>. Another variation is the 16-hour overnight fast where eating is restricted <em>every day</em> to an eight-hour window, such as 11am to 7pm. Across all types of intermittent energy restrictions diets, we don’t know the <a href="https://www.ncbi.nlm.nih.gov/pubmed/28106818">longer-term benefits or harms</a>. </p>
<p>Any intermittent fasting approach will work if you can tolerate the hunger pains and stick to it. Sounds easy, but it is a very hard thing to do and for many it is not realistic. When you are fasting, your body thinks there is a <a href="https://theconversation.com/health-check-why-diets-fail-20066">famine and will try to get you to eat</a>. The idea is that by including non-fasting periods, when you eat what you want, you may feel less like you are on a “diet”, and <em>that</em> makes it easier to stick to.</p>
<p>Even though “fasting” dieters are told to eat what they feel like on non-fast days, most <a href="https://www.ncbi.nlm.nih.gov/pubmed/27062219">do not get a compensatory increase in appetite</a>. In other words, they do not over-eat, but just eat normally on non-fast days. So they reduce their total kilojoule intake over the whole week.</p>
<h2>How about very low energy diets?</h2>
<p>A specific type of continuous (every day) fasting diet is called a protein sparing modified fast or a very low energy diet. These limit you to 1,800 to 2,500 kilojoules a day, every day. They use products called <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1747-0080.2012.01628.x/full">formulated meal replacements</a>, in the form of milkshakes or snack bars to replace most meals and snacks. These are supplemented with vitamins and minerals to meet the body’s nutrient needs. </p>
<p>Such very low energy programs usually include one small meal that contains a couple of cups of vegetables (to boost fibre and nutrient intakes), a small amount of oil (to keep the gall bladder working) and sometimes a fibre supplement (to manage constipation). These are reserved for when you need to lose weight urgently for health reasons or ahead of surgery.</p>
<p>Continuous fasting using these very low energy diets is associated with a <a href="https://www.ncbi.nlm.nih.gov/pubmed/25402637">reduction in hunger</a>. This is thought to be due to the production of molecules called <a href="http://www.webmd.com/diabetes/ketones-14241#1">ketones</a> that cross the <a href="https://theconversation.com/explainer-what-is-the-blood-brain-barrier-and-how-can-we-overcome-it-75454">blood-brain barrier</a> (from the brain’s bloodstream into its tissues) and reduce appetite.</p>
<h2>Do ‘fasting’ diets work?</h2>
<p>Intermittent fasting diets that last for at least six months <a href="https://www.ncbi.nlm.nih.gov/pubmed/27338458">help people lose weight</a>. However, they are no more effective than other dietary approaches that restrict your kilojoule intake every day, but not so severely as a “fast”.</p>
<p>Consistent with this result, a study published last week <a href="https://www.ncbi.nlm.nih.gov/pubmed/28459931">randomised 100 adults </a> to either alternate-day fasting, a continuous energy restriction diet, or to no intervention, for six months. They were followed for another six months after that. There was no difference in weight loss between the diet groups after a year.</p>
<p>And <a href="https://www.ncbi.nlm.nih.gov/pubmed/26775902">a review</a> that compared behavioural interventions for weight management to those that also included very low energy diets found very low energy approaches achieved slightly greater weight loss for up to two years.</p>
<h2>Who should not try a fasting diet?</h2>
<p>Fasting diets are not for everyone. People with major medical problems, or taking a range of medications including insulin, should not go on them, unless under medical supervision; they are not suitable for children, in pregnancy or for people with eating disorders; and they may exacerbate some mental health conditions. </p>
<p>Fasting diets can also have side-effects. The more days you spend “fasting”, the more likely you are to have them. <a href="https://www.ncbi.nlm.nih.gov/pubmed/26775902">Side-effects can include</a> constipation, headaches, bad breath, <a href="https://theconversation.com/got-gallstones-heres-what-to-eat-and-avoid-53229">gall bladder</a> disease, <a href="https://theconversation.com/got-gout-heres-what-to-eat-and-avoid-50239">gout</a> and liver inflammation. </p>
<p>So, before starting a weight loss diet, see your doctor for a check-up. When you need more support to improve your eating habits, or the diet you were following stops working, you need to try another approach. That is a good time to also get advice from an <a href="https://daa.asn.au/find-an-apd/">Accredited Practising Dietitian</a>. </p>
<h2>What is the best diet for weight loss?</h2>
<p><a href="https://theconversation.com/health-check-whats-the-best-diet-for-weight-loss-21557">The best diet</a> to help you achieve a healthy weight is one you can stick with. It should also help you feel better and be healthier. </p>
<p>By making improvements to your usual eating habits, that you can live with permanently, you will drop some weight. It might <a href="https://theconversation.com/you-dont-have-to-be-the-biggest-loser-to-achieve-weight-loss-success-11587">not be your dream weight</a>, but it is likely to be realistic. It might not sound sexy, but it’s true.</p><img src="https://counter.theconversation.com/content/76644/count.gif" alt="The Conversation" width="1" height="1" />
<h4 class="border">Disclosure</h4><p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research fellow. She has received a range of research grants including NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, the Heart Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers and the Sax Institute. She is a spokesperson for the Dietitians Association of Australia on some specific nutrition issues, including Australia's Healthy Weight Week.</span></em></p>Fasting diets aim to make it easier to stick to a weight loss program, but they are not for everyone.Clare Collins, Professor in Nutrition and Dietetics, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/388082015-03-26T10:29:32Z2015-03-26T10:29:32ZFeast then famine – how fasting might make our cells more resilient to stress<figure><img src="https://images.theconversation.com/files/75981/original/image-20150325-14488-b8xwni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Not too much.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-44883559/stock-photo-small-portion-of-pasta.html?src=2_UGTe3ioXVCZlf2gepG9Q-1-3">Pasta via www.shutterstock.com</a></span></figcaption></figure><p>Intermittent fasting (also called alternate day fasting) has become a <a href="http://thefastdiet.co.uk/">popular diet</a>. In most versions of intermittent fasting, people fast or eat very little a few days each week and then eat normal amounts during the remaining days. </p>
<p>Fasting is something that human beings have practiced throughout history, often out of circumstance rather than choice. Our hunter-gatherer ancestors were probably expert fasters, indulging in feasts in times of plenty, and then facing long periods of scarcity in between. With this in mind, it makes sense that our bodies’ cells could perform well under the harsh conditions of feast and famine.</p>
<p>As a group of medical and research students, we wanted to know if fasting causes our cells to become more resilient to damage in the absence of weight loss. And do these benefits depend on the temporary stress that fasting causes in our cells?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/75978/original/image-20150325-14504-13wtgpy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Why not try both?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-5527483/stock-photo--feast-or-famine-road-sign-with-dramatic-clouds-and-sky.html?src=7Vn9BeTvhIWiMP9nFuDwlw-1-0">Sign via www.shutterstock.com.</a></span>
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<h2>Intermittent fasting may have anti-ageing benefits</h2>
<p>Scientists have been looking at the possible health benefits of calorie restriction for years. </p>
<p>A prominent theory <a href="http://dx.doi.org/10.1016/j.cmet.2013.12.008">suggests</a> these health benefits are related to the drop in blood sugar that results from fasting, which pushes our cells to work harder to utilize other forms of energy.</p>
<p>Rhesus monkeys eating only 70% of their normal caloric intake have been shown to <a href="http://dx.doi.org/10.1038/ncomms4557">live much longer</a> and are much healthier at older ages. These anti-aging benefits have also been <a href="http://ajcn.nutrition.org/content/86/1/7.full">seen in animals</a> that are put on an intermittent fasting diet, alternating between days of normal eating and days where calories are restricted. More recently, scientists have discovered some similar effects in <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/pmid/17291990/">humans</a>. </p>
<p>What isn’t clear, though, is why intermittent fasting seems to have a benefit in the fight against aging. This question is complicated by the fact that in all studies performed in people, fasting led to weight loss. The health benefits of weight loss might be overshadowing the other benefits obtained from fasting alone. </p>
<h2>Free radicals damage cells, but fasting may help</h2>
<p>One way that our cells can become damaged is when they encounter <a href="http://www.ncbi.nlm.nih.gov/pubmed/10693912">oxidative stress</a>. And preventing or repairing cell damage from oxidative stress is helpful against ageing. This stress happens when there is higher-than-normal production of free radicals, such as reactive oxygen species. These are unstable molecules that carry highly reactive electrons.</p>
<p>When one of these free radicals encounters another molecule, it may either give up an electron or take another electron. This can result in a rapid chain reaction from molecule to molecule, forming more free radicals, which can break apart connections between atoms within important components of the cell, like the cellular membrane, essential proteins or even DNA. Anti-oxidants work by transferring the needed electrons to stabilize the free radicals before they can do any harm.</p>
<p>Although fasting seems to help our cells combat damage from this process, it isn’t clear exactly how that happens. </p>
<p>Free radicals can be generated by poorly functioning mitochondria (the powerhouses of the cell). The switch between eating normally and fasting causes cells to temporarily experience lower-than-usual levels of glucose (blood sugar), and they are forced to begin using other sources of less readily available energy, like fatty acids. This can cause the cells to turn on survival processes to remove the unhealthy mitochondria and replace them with <em>healthy</em> ones over time, thus reducing the production of free radicals in the long-term. </p>
<p>It might also be true that fasting itself results in a small increase in free radical production early on during fasting. </p>
<p>The cells may respond by increasing their levels of natural anti-oxidants to fight against future free radicals. And although free radicals are commonly seen as harmful because of their ability to damage our cells, they might be important short-term signals for our body in this case, triggering cells to <a href="http://dx.doi.org/10.1016/j.cmet.2013.12.008">cope better</a> with more severe stresses that may come in the future. </p>
<h2>Do fasting and feasting fight aging?</h2>
<p>To understand how fasting might make cells stronger, we recruited 24 people and asked them to <a href="http://dx.doi.org/10.1089/rej.2014.1624">practice an intermittent fasting diet</a> for two three-week periods. During the first fasting period, participants ate a specially calibrated diet and during the second three week period, they ate that diet and took oral supplements of Vitamin C and Vitamin E, which are both anti-oxidants. </p>
<p>Because we just wanted to focus on how intermittent fasting affected cells, and not weight loss, participants ate 175% of their normal daily calorie intake on feasting days, and 25% of their normal daily intake on fasting days to prevent weight loss. We provided and carefully tracked the volunteer’s food. They ate typical American fare – things like pasta, chicken, sandwiches and desserts like ice cream. </p>
<p>We took samples of blood before they started and just after they ended the diet so we could compare levels of byproducts of oxidative stress and markers of strong cell functioning. </p>
<p>During the first three week period we attempted to see if fasting would increase oxidative stress (free radicals) in each person’s cells and to see if this stress actually led to stronger, more resilient cells.</p>
<p>Then we wanted to see if taking antioxidants in the second fasting period would block the free radicals caused by the fasting, preventing the cells from becoming more resilient. In other words, we wanted to know if Vitamin C and E would shelter the cells to the point that they wouldn’t be ready to stand up for themselves later on. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/76028/original/image-20150325-14515-qbn3m9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Anti-oxidants, like Vitamin C, can shelter cells from oxidative stress.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-48588532/stock-photo-pills-of-vitamin-c-spilled-out-open-container-on-white-background.html?src=g-GrJczcORbTE6QBXqWAMw-2-60">Vitamin C tablets via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>How did intermittent fasting affect people’s bodies?</h2>
<p>We found that in response to fasting every other day, the cells made more copies of a gene called SIRT3, which is part of a pathway that works to prevent free radical production and <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3711519/">improve cellular repair processes</a>. </p>
<p>We also found a significant decrease in levels of circulating insulin, a sign that the participants bodies were more responsive to this hormone. This is important because when we become less sensitive to insulin, we are at risk for diabetes.</p>
<p>One somewhat surprising finding is that when participants took daily oral supplements of Vitamin C and E, the benefits from fasting disappeared. It seems that because the cells were relatively sheltered from experiencing any oxidative stress that may have been caused by fasting every other day, they didn’t respond by increasing their natural defenses and improving their sensitivity to insulin and other stress signals. </p>
<p>This suggests that low levels of environmental stress from things like fasting are actually good for our bodies, and that antioxidant supplements, while potentially good at certain times, might actually prevent our normal healthy cellular responses in other situations.</p>
<p>Although our study was relatively small and only had people fasting every other day for a short time period, we were able to pick up on a few important health benefits of fasting that happened even when people weren’t losing any weight at all. We look forward to other studies of intermittent fasting that might show more pronounced, longer-term benefits in larger groups of people.</p>
<hr>
<p><em>This article has been updated to correct information about free radicals and anti-oxidants.</em></p><img src="https://counter.theconversation.com/content/38808/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Douglas Bennion receives research funding and fellowship training support from the National Institutes of Health, the American Heart Association, and the McKnight Brain Institute at the University of Florida.</span></em></p><p class="fine-print"><em><span>Martin Wegman receives research funding and fellowship training support from the National Institutes of Health, the Doris Duke Charitable Foundation and the American Medical Association Foundation.</span></em></p><p class="fine-print"><em><span>Michael Guo receives funding from the National Institutes of Health and the March of Dimes Foundation.</span></em></p>Alternate day fasting stresses cells, which may make them stronger.Douglas Bennion, MD-PhD student and NIH T32 Pre-doctoral Fellow, University of FloridaMartin Wegman, MD-PhD student and NIH TL1 Pre Doctoral Fellow, University of FloridaMichael Guo, MD-Phd student, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/138202013-06-12T20:33:47Z2013-06-12T20:33:47ZHere’s the skinny on fasting for weight loss – the 5:2 diet<figure><img src="https://images.theconversation.com/files/25163/original/ds5h6k9q-1370504002.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">People on the diet need to restrict intake of calories on fasting days.</span> <span class="attribution"><span class="source">Martin Lee</span></span></figcaption></figure><p>The “new” weight-loss strategy known as the 5:2 diet has been receiving much attention in the media since the book <a href="http://thefastdiet.co.uk/">The Fast Diet: The Secret of Intermittent Fasting - Lose Weight, Stay Healthy, Live Longer</a> was launched late last year. </p>
<p>The 5:2 diet allows you to eat as usual for five days and to fast for two days. On fasting days, the dieters need to restrict intake of food to approximately 2000 kilojoules (500 calories) a day for women or 2400 kilojoules (600 calories) for men. </p>
<p>The two days of fasting don’t have to be consecutive and you can decide how you want to spread your food intake on those days as long as you adhere to energy restriction. The food consumed during the two fasting days should have little fat and carbohydrate content and alcohol consumption is not recommended.</p>
<p>During the two fasting days, you are typically allowed protein foods such as eggs, or low-fat yogurt or cheese for breakfast and protein foods such as chicken, fish, lean meat, along with salad or other non-starchy vegetables for lunch or dinner. You are permitted water, green tea, or black coffee. While you can have milk with your beverages, it must be counted toward your caloric intake.</p>
<h2>Not a fad?</h2>
<p>Intermittent fasting or restricting energy intake for weight loss, which is what the diet is based on, is not a new concept. And there are <a href="http://www.ncbi.nlm.nih.gov/pubmed/19793855">other kinds of fasting diets</a> around, such as “alternate day fasting”. But while energy restriction in the form of various weight-loss diets has been investigated in both humans and animals, there’s little research regarding the utility of intermittent fasting in humans.</p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/20921964">A 2011 study</a> in the United Kingdom that investigated the effects of intermittent energy restriction (to approximately 2266kJ a day for two days) compared to continuous energy restriction (approximately 6276KkJ a day for seven days a week) over six months, in 107 young overweight or obese women. It reported that both diets were equally effective for weight loss, as well as other markers of good health.</p>
<p>But there seemed to be potential difficulties in adherence. At the completion of the study, only 58% of the women in the intermittent fasting group planned to continue with the diet, compared to 85% of those in the energy-restricted group.</p>
<p>This study was one of the largest undertaken in this area so far and the few previous studies in the field have had a much smaller number of participants. Although these smaller studies have been conducted for shorter time periods, the UK study is also considered to be relatively short term.</p>
<p>Weight loss within the first six months is common with a lot of different types of diets. But research studies have shown that the majority of people put much of the weight back on within three to five years.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/24610/original/r7r2rgpx-1369807370.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Many people who tried the 5:2 diet reported weight loss but did the weight stay off?</span>
<span class="attribution"><span class="source">Nata-Lia</span></span>
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<h2>Need for caution</h2>
<p>Many people who have tried the 5:2 diet report that they have been successful in losing weight but this is the case for most weight-loss diets in the short term. The issue of long-term compliance with the two days of energy restriction remains unresolved, as does long-term weight maintenance because people usually are not able to keep to their new weight. </p>
<p>Difficulties in adherence resulting in weight regain may encourage some people to try another dieting attempt and this can lead to the cycle of weight loss and weight regain being repeated. This happens in most cases of dieting-related weight loss.</p>
<p>The risks or the potential to overeat or gorge on non-fasting days also needs to be investigated. Diet quality is of particular significance for those who fast intermittently to ensure that all nutritional requirements are met and that the intake of some nutrients that have low intakes anyway (such as calcium) is not further compromised.</p>
<p>What’s more, we still need to investigate whether intermittent fasting is a <em>safe</em> weight-loss strategy, especially for people with diseases such as diabetes. Starvation-type diets have side-effects such as dehydration, anxiety, irritability, tiredness and lethargy and whether we should be looking out for these in the 5:2 diet remains to be determined.</p>
<p>Intermittent fasting is reported to be effective among those who have used it for weight loss and it seems to be as effective as an energy-restricted diet in the short term. It may be a viable weight-loss option for some people but we need to research its effects beyond those reported, especially since many of these effects are anecdotal at present. </p>
<p>It’s best to follow healthy eating dietary guidelines and seek advice from your doctor before embarking on intermittent fasting as a weight-loss strategy.</p><img src="https://counter.theconversation.com/content/13820/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Surinder Baines does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The “new” weight-loss strategy known as the 5:2 diet has been receiving much attention in the media since the book The Fast Diet: The Secret of Intermittent Fasting - Lose Weight, Stay Healthy, Live Longer…Surinder Baines, Associate Professor in Nutrition and Dietetics , University of NewcastleLicensed as Creative Commons – attribution, no derivatives.