When we talk about obesity and weight management, eating behaviour is often part of the conversation. But it can be tempting to assume that someone’s eating patterns are simply a consequence of their body weight or BMI.
New genetic research suggests the relationship is much more complicated.
A large study published in Nature Mental Health in August 2026 investigated the genetics associated with binge eating behaviour and anorexia nervosa. Researchers found that most of the genetic variation associated with these conditions was separate from the genetic factors associated with BMI.
For people considering weight loss treatment, the research provides another useful reminder that eating behaviour, body weight and health are connected in complex ways, and each may need to be considered individually.
What Did the New Research Find?
The genomic study included nearly 40,000 people with binge-eating behaviour, around 24,000 people with anorexia nervosa and more than 1.2 million control participants. Researchers identified several genetic regions associated with the two conditions.
BMI-related genetics explained only around 12% of the genetic variation associated with binge eating and around 10% of that associated with anorexia nervosa.
In other words, most of the genetic variation associated with these eating behaviours could not be explained simply by genetic factors linked to body weight. The researchers also found connections with other traits. Binge-eating behaviour, for example, showed genetic associations with ADHD, risk-taking, problematic alcohol use and smoking.
The findings show how complex eating behaviour can be, with biological and psychological factors playing a role alongside body weight. The research is still developing, but understanding these genetic influences may help researchers learn more about why eating disorders develop and how they could be better understood and treated in the future.
What Is Binge Eating?
Binge eating generally involves episodes in which someone consumes a large amount of food while experiencing a sense of loss of control over their eating. It is important, however, to distinguish occasional overeating from a diagnosed eating disorder.
Binge eating disorder is a recognised mental health condition that requires appropriate assessment and treatment. Someone’s body size alone cannot tell us whether they have an eating disorder.
The new research reinforces this distinction. Although there was some genetic overlap between body weight and binge eating, most of the genetic variation identified by the researchers was independent of BMI-related genetics.
Why Eating Behaviour Matters in Bariatric Care
Eating behaviour is particularly relevant when someone is considering bariatric surgery because surgery changes both stomach anatomy and the way patients need to eat afterwards.
Procedures such as gastric sleeve surgery and gastric bypass surgery support weight loss through changes to the digestive system, but they also require long-term changes to portion sizes, food choices and eating patterns.
This is one reason bariatric care involves much more than assessing someone’s weight alone. BMI is just one part of the picture when considering weight loss surgery, alongside a person’s wider health and individual circumstances.
A specialist assessment considers a person’s wider health and circumstances, including their medical and weight history, previous weight-management attempts and nutritional needs.
Where there are concerns about eating behaviours or psychological wellbeing, these may also need appropriate assessment and support before or alongside bariatric treatment.
Does Binge Eating Mean You Cannot Have Bariatric Surgery?
Not necessarily. Eating behaviours and individual circumstances vary considerably, which is why they need to be assessed on an individual basis rather than used as a simple yes-or-no test for surgery. However, an active eating disorder or significant concerns around eating behaviour should not be overlooked.
The aim of assessment is to understand whether surgery is appropriate and whether additional psychological support may be needed to help someone prepare for the dietary and behavioural changes that follow bariatric surgery.
Importantly, bariatric surgery itself is not a treatment for an eating disorder.
Weight and Eating Behaviour Are Not the Same Thing
This research reinforces an important point. A person’s weight does not tell us everything about how or why they eat. Eating behaviours can have many influences and should not be understood simply by looking at someone’s body weight.
The same applies when someone is considering bariatric surgery. Every person has a different medical history, weight journey, eating patterns and individual circumstances.
At Phoenix Health, this is why assessment is an important part of the bariatric journey. Our multidisciplinary team looks at the wider picture, helping patients understand their treatment options and prepare for the dietary and behavioural changes that come with weight loss surgery.
If you’re considering bariatric surgery and have concerns about binge eating or other eating patterns, it’s important to discuss them openly with your healthcare team. Identifying any concerns before surgery can help ensure that the right support is considered as part of your individual treatment pathway.
Reference:
Davies H, et al. “Genomic insights into anorexia nervosa and binge-eating behavior.” Nature Mental Health. Published 19 August 2026. https://www.nature.com/articles/s44220-026-00698-2
Medically Reviewed by Lujain Alhassan, BSc, ANutr
Registered Associate Nutritionist and Bariatric Nutrition
