Feeling Depressed Associated With Weight Gain

Previous research has suggested a connection between weight and mental health with each potentially influencing each other but the connection is complex and poorly understood. To investigate the connection the researchers analyzed data from over 2,000 adults who completed digital questionnaires on mental well-being and body weight every month for up to nine months using a mobile application. 

The questions were designed to assess symptoms of depression, anxiety, and perceived stress. The higher the score, the greater the severity with 24 being the maximum score for depression, 40 for stress, and 21 for anxiety. Statistical modeling was used to analyze whether having poorer mental well-being than usual was related to changes in body weight one month later.

According to the researchers, for every increment increase in score for depressive symptoms, the participant’s subsequent weight one month later increased by 45g. For example, an increase from mild (score of 5) to moderate symptoms (score of 10) would relate to an average weight gain of 225g (0.225kg). 

This effect was only found among those who were overweight (BMI from 25-29.9 kg/m2) or those with obesity (BMI over 30 kg/m2). Those who were overweight on average had an increase of 52g for every increment point increase from their usual depressive symptom score, and those who were obese had a comparable weight gain of 71g. It was noted that this effect was not seen among those with a healthy body weight, and no evidence was found that perceived stress or anxiety was related to changes in weight.

“Overall, this suggests that individuals with overweight or obesity are more vulnerable to weight gain in response to feeling more depressed. Although the weight gain was relatively small, even small weight changes occurring over short periods of time can lead to larger weight changes in the long-term, particularly among those with overweight and obesity,” said first author Dr. Julia Mueller from the MRC Epidemiology Unit. "People with a high BMI are already at greater risk from other health conditions, so this could potentially lead to a further deterioration in their health. Monitoring and addressing depressive symptoms in individuals with overweight or obesity could help prevent further weight gain and be beneficial to both their mental and physical health.”

“Apps on our phones make it possible for people to answer short questions at home more frequently and over extended periods of time, which provides much more information about their wellbeing. This technology could help us understand how changes in mental health influence behaviour among people with overweight or obesity and offer ways to develop timely interventions when needed,” said senior author Dr. Kirsten Rennie from the MRC Epidemiology Unit.