ECN Spotlight – Julia Mueller

ECN Spotlight – Julia Mueller

We are pleased to meet with Dr Julia Mueller , a researcher at the MRC Epidemiology Unit , University of Cambridge. She works within a programme on the Prevention of Diabetes and Related Metabolic Disorders in High Risk Groups , led by Dr Amy Ahern  and Professor Simon Griffin . She is also a member of the Operations Committee for the UK Association for the Study of Obesity , and leads their Early Career Researcher network. Her passion lies in understanding the links between psychology and obesity and harnessing this to develop behavioural weight management interventions that can help people manage their weight and improve their overall wellbeing.

Julia, why is it important to consider mental wellbeing in the context of obesity?

Mental wellbeing and obesity are closely interlinked. Not only can obesity impact mental health, but mental health challenges may also contribute to the development and exacerbation of obesity. Periods of prolonged stress and low mood can affect the way we eat and how much we exercise. Such periods can even lead to metabolic changes that promote abdominal fat deposition, meaning that, even if diet and physical activity remain unaffected, longer periods of stress can change our body and the way (and where) it stores fat.

Understanding the relationship between mental wellbeing and obesity is essential for effective intervention strategies. However, studies investigating this relationship have often been cross-sectional or spanned extended periods between measurements. This allows limited insight, particularly in relation to how changes in an individual’s mental health influence their bodyweight over time.

How did you explore this?

To help us better understand how changes in mental wellbeing might influence weight, myself and colleagues at Cambridge’s Medical Research Council (MRC) Epidemiology Unit examined data from over 2,000 adults living in Cambridgeshire, UK, who were participating in the Fenland COVID-19 cohort study. Participants completed monthly digital questionnaires on mental health and bodyweight during the COVID-19 pandemic (August 2020 – April 2021) using a mobile app developed by Huma Therapeutics Limited.

The study, published in PLOS ONE , found that fluctuations in depressive symptoms within individuals predicted subsequent higher weight: with each unit increase from a person’s typical level of depressive symptoms (using a questionnaire with scores ranging from 0-24), their weight a month later increased by 45 grams. When we examined the relationship separately by BMI category, we only found this effect among those living with overweight (BMI 25-29.9 kg/m2) or obesity (BMi≥30kg/m2), not among those with BMI<25kg/m2.

What do the results mean?

This suggests that individuals with overweight or obesity are more vulnerable to weight gain in response to feeling more depressed. This vulnerability is likely due to a combination of genetic predispositions and learned behaviours (e.g., emotional eating).  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. For example, previous research has found that small weight increases gained over short periods – e.g., over Christmas or other holidays – can become permanent and lead to further weight gain over time.

What are the next steps or future plans for this project?

This exploration opens avenues for future research, encouraging a more nuanced approach to the development of behavioural weight management interventions and emphasising the need for tailored strategies based on changes in an individual’s mental wellbeing. It may be beneficial to monitor fluctuations in depressive symptoms over time and intervene when more support is needed.

If you are interested in collaborating or finding out more about this work, please find contact details here: