In this article Dr Laura Kudlek discusses the implications of two new research papers she led while a PhD student at the MRC Epidemiology Unit, which examined the impact of Acceptance and Commitment Therapy on eating behaviour traits and weight loss.

Weight loss programmes can improve health – even if not all the weight stays off. But the fact that results are often short-lived can be frustrating. There are different types of weight management programmes, and recently, programmes based on a type of psychological therapy called “Acceptance and Commitment Therapy”, or ACT, have shown particular promise in studies looking at long-term impact.

ACT helps people change how they relate to difficult thoughts, feelings and bodily sensations, rather than letting these experiences control their behaviour. Instead of trying to get rid of cravings or negative emotions, ACT teaches people to notice and accept them, while still making choices that align with their personal values. This is usually done through exercises and learning materials designed to support this shift in perspective and put it into practice in everyday situations. For example, someone might recognise a craving for their favourite sweet, notice how it feels in their body, and reflect on where its coming from – perhaps they are not all that hungry, but feeling frustrated after a challenging day at work. Making these non-judgemental observations may help them to accept the experience and then choose an alternative action that supports their health.

Although ACT-based programmes have shown encouraging results, we still don’t fully understand what contributes to how they work – or who is most likely to benefit from them.

The how: The role of eating behaviour traits

In the early 2000s, researchers began to suggest that eating behaviour traits could help explain why some people develop obesity and some don’t, despite living in the same environment. Eating behaviour traits are defined as personal tendencies that determine how one reacts to food, and when combined with an environment full of highly palatable, energy-dense foods, they may help explain rising obesity rates. For example, the eating behaviour traits “emotional eating” and “internal disinhibition” describe how someone eats in response to negative thoughts and emotions, and these traits vary between people.

While having higher levels of certain eating behaviour traits may explain how higher bodyweight develops in some people, changes in these traits may explain how different weight loss programmes work. Our research team at the University of Cambridge recently analysed data from 1,391 adults with overweight or obesity who took part in eight ACT-based studies to explore to what extent changes in peoples eating behaviour traits were responsible for weight loss in this treatment. We found that improvements in eating behaviour traits like emotional eating, internal disinhibition and restraint were responsible for around a quarter of weight loss produced by the ACT programmes one year after they ended. This suggests that targeting eating behaviour traits may be one of the ways ACT helps people lose weight, – and highlights them as an important focus for treatment.

The who: Should we personalise programmes?

But do ACT-based treatments work equally well for everyone? Researchers have been increasingly interested in why some people lose weight and keep it off, while others don’t – even when they’re following the same program.

As part of the same study, we also looked at whether the levels of eating behaviour traits people have at the start of ACT-based programmes may influence how much weight people lose after the programme. We found some initial evidence that people with moderate levels of emotional eating or internal disinhibition tended to lose more weight than those with very high levels. This could suggest that while ACT works well for those who struggle moderately with emotion-related eating, people with more severe problems may need more intensive support.

Final thoughts: Matching support to people

Weight management is complex – biologically, environmentally, socially and psychologically. While programmes like ACT are promising, they may not be one-size-fits-all, with some people likely requiring additional support. By understanding why some people benefit more than others, and how those benefits occur, we move closer to developing more effective, longer lasting, and personalised treatment approaches. However, this research is still in its early stages.

Our findings need to be confirmed in future studies, ideally involving larger and more diverse groups. But they point in a hopeful direction: that by paying more attention to psychological traits, we might be able to better match people with the support that works best for them.

References

• Laura Ludlek et al. An individual participant data meta-analysis investigating the mediating role of eating behavior traits in Acceptance and Commitment Therapy-based weight management interventions. Annals of Behavioural Medicine. 02 June 2025. DOI:10.1093/abm/kaaf039
• Laura Kudlek et al. Individual participant data meta-analysis of eating behaviour traits as effect modifiers in acceptance and commitment therapy-based weight management interventions. International Journal of Obesity. 10 April 2025. DOI:10.1038/s41366-025-01759-9

Image courtesy of the World Obesity Federation.