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Monday’s medical myth: exercise makes you eat more food and gain weight

Exercise decreases hunger in the long term. Puuikibeach/Flickr

It’s time to ignore any advice you’ve heard about your sweat and hard work in the gym sabotaging your weight loss efforts by causing you to eat more. Every little bit of exercise can help shift unwanted flab.

So, is dieting the only way to lose weight, or does it all boil down to becoming more active?

Some argue weight loss is all about how much (or how little) a person eats, while others support the view that it’s mostly a person’s activity (or lack of it) that most affects weight loss or gain.

A more extreme view that occasionally surfaces is that exercise only drives an increased appetite for food, and the extra calories consumed surpass those burned during the exercise.

If this is really the case, the argument becomes “why even bother getting active at all?”

Before this myth is dispelled by a wealth of scientific studies, a simple observation shows it’s false. Just look at any group of high performing athletes such as marathon runners, cyclists or swimmers. These athletes eat mountains of food each day but all of this is used up in their training endeavours. Overweight and obesity is hardly an issue for athletes.

So what does the science say?

A 2007 systematic review teased out the different effects that dieting and exercise can have on weight loss. The firm conclusion of the review wasn’t exactly surprising: exercise has a modest, but consistent benefit on body fat reduction and this benefit is independent of dieting.

The authors also found evidence to support a “dose” effect with increasing amounts of exercise leading to greater weight loss: the more you move, the more you lose.

Giving a small amount of credence to this myth though, the review did note that exercise can generate short-term increases in hunger that can cause a person to eat more. But in the longer term, there is an overall decrease in a person’s feelings of hunger.

Adding more evidence to debunk this exercise/weight-gain myth, a Cochrane Review concluded that exercise has a positive effect on body weight and cardiovascular disease risk factors in people who are overweight or obese, especially when combined with dietary changes.

Even if little weight is shed through this exercise, there are a myriad of health gains such as reduced risk of cardiovascular disease, and improved bone and muscle health, mood, sleep patterns, and even reduced cancer risk.

Now for the painful part.

Current Physical Activity Guidelines for Australians of 30 minutes of moderate-intensity activity on most days of the week may not be enough to stave off long-term weight gain.

For people who are already overweight, research shows that even 60 minutes of physical activity each day may not be enough to halt weight gain.

For those breaking out in a sweat just thinking about that much activity, what it really means is we need to pay more attention to the food side of the energy balance equation.

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