Feelings of depression linked to short-term increase in body weight, study finds

Increased symptoms of depression are associated with a subsequent increase in body weight when measured a month later, according to a new study from the University of Cambridge.

The study, published in PLOS ONEfound that the increase was only seen in people who were overweight or obese, but found no link between generally having greater depression symptoms and higher body weight.

Research has suggested a link between weight and mental health, with each potentially influencing the other, but the relationship is complex and remains poorly understood, particularly in relation to how changes in an individual’s mental health influence its weight over time.

To help answer this question, researchers from the Medical Research Council (MRC) Cambridge Epidemiology Unit examined data from more than 2,000 adults living in Cambridgeshire, UK, who had been recruited for the Fenland COVID-19 study.

Participants completed digital questionnaires on mental well-being and body weight monthly for up to nine months during the COVID-19 pandemic (August 2020-April 2021) using a mobile app developed by Huma Therapeutics Limited.

The questions assessed an individual’s symptoms of depression, anxiety, and perceived stress. A higher score indicated greater severity, with the maximum possible scores being 24 for depression, 21 for anxiety, and 40 for stress. The team then used statistical modeling to determine whether poorer-than-usual mental well-being was linked to changes in body weight a month later.

The researchers found that for every increase in an individual’s usual score for depressive symptoms, their subsequent weight one month later increased by 45g. This may seem small, but it would mean, for example, that in an individual whose depressive symptoms score increased from five to 10 (which equates to an increase in “mild” to “moderate” depressive symptoms), this would correspond to an average weight gain of 225 g. (0.225 kg).

This effect was only observed in overweight individuals (defined as a BMI of 25 to 29.9 kg/m).²) or suffering from obesity (BMI greater than 30 kg/m²). Overweight people had on average an increase of 52 g for each point increase from their usual depressive symptom score and for obese people the comparable weight gain was 71 g. The effect was not observed in individuals with a healthy weight.

First author Dr Julia Mueller from the MRC Epidemiology Unit said: “Overall, this suggests that people who are overweight or obese are more vulnerable to weight gain in response to a feeling of increased depression. Although the weight gain was relatively small, even small weight changes occur. over short periods of time can lead to greater weight changes in the long term, especially in overweight and obese people.

“People with a high BMI are already at greater risk for other health problems, which could potentially lead to further deterioration in their health. Monitoring and treating depressive symptoms in people who are overweight or obese could help prevent additional weight gain and be beneficial for both their mental and physical health.

The researchers found no evidence that perceived stress or anxiety was linked to weight changes.

Lead author Dr Kirsten Rennie from the MRC Epidemiology Unit said: “Apps on our phones allow people to answer short questions at home more frequently and over extended periods of time, which provides much more information about their well-being. Technology could help us understand how changes in mental health influence the behavior of people who are overweight or obese and offer ways to develop timely interventions when needed.

Although previous studies have suggested that poor mental health is both a cause and consequence of obesity, the research team found no evidence that weight predicted later symptoms of depression.