Losing weight might make you healthier but not happier

Temptation is everywhere. Vivian Viola, CC BY-NC

Supermodel Kate Moss’ quip that “nothing tastes as good as skinny feels” captured the sense in society that being thin is the recipe for happiness. Obesity causes a range of health problems, including diabetes, but will losing weight really make you happier?

While there’s no doubt that losing weight can significantly improve your physical health, in research published in PLOS ONE we found that the effect on mental health was less straightforward. We studied 1,979 overweight and obese people who lost 5% or more of their weight over four years and found that they were more likely to report feeling depressed than those who remained within 5% of their original weight.

Our participants came from the English Longitudinal Study of Ageing, which collects data from adults aged 50 or older, and we excluded participants who already had clinical depression or a debilitating illness. While nurses monitored weight loss, depressed mood and overall well-being were assessed using questionnaires. Of the 1,979 participants, 278 (14%) lost at least 5% of their initial body weight (an average of 6.8kg each). Before adjusting for serious health issues and major life events such as bereavement – which can cause both weight loss and depressed mood – they were 78% more likely to report depressed mood. Without these issues, over half (52%) were still more likely to feel low, still a significant number.

Studies have shown that losing weight can improve mood, but this could be a result of a supportive environment rather than the weight loss itself because improvement in mood is often seen very early on in treatment and not tied to the amount of pounds that are shed. The results of our study show an associated risk of developing depressed mood – even after accounting for an intention to lose weight (not because of a health condition for example), changes in physical health, and life stress.

The finding doesn’t necessarily mean that losing weight directly causes depression, because both depression and weight loss may share a common cause. But what it does mean is that we can’t assume that losing weight will improve mood and make you happier in life. And it might explain why people struggle to maintain weight loss.

Significant physical benefits

It is generally recommended that obese people lose weight and a recent UK survey found that 60% of overweight and obese adults were trying to do so. Like previous studies have found, we also saw favourable changes in risk factors for cardiovascular disease, with people who lost weight less likely to have high blood pressure or high levels of triglyceride (a type of fat found in the blood).

Based on this, we wouldn’t want to discourage anyone from trying to lose weight but rather that people shouldn’t expect it to be a magical cure that improves everything in their lives. Aspirational advertising by diet brands may give people unrealistic expectations – they often promise instant improvements that may not be borne out in reality. People should be realistic about weight loss and be prepared for the challenges.

Unhealthy food is all around us and as anyone who’s ever been on a diet would understand, resisting the temptation requires considerable willpower that can take a mental toll. It may also involve missing out on some enjoyable activities. However, mood may improve once target weight is reached and the focus is on weight maintenance.

Weight loss is undoubtedly a good thing for health, but it’s important that health professionals also take note of psychological well-being when recommending or monitoring weight loss. And people who are trying to lose weight shouldn’t be afraid to seek help, whether from friends, family or professionals. In the long run it could mean the pounds are more likely to stay off.