What animal studies reveal about binge-eating behaviour

Binge eating, especially on high-fat, high-sugar foods, can rewire the brain and alter behaviour, leading to compulsive food-seeking and a greater likelihood of overeating instead of undereating when stressed. It can also contribute to long-term physical health problems, according to a new review of animal studies.

“Binge eating is often misunderstood as simply overeating, or snacking in front of the TV. However, it’s a recognised mental health disorder that affects millions of people worldwide,” said lead author Dr Simone Rehn from the University of Technology Sydney (UTS).

“With binge eating disorder, people consume a large amount of food, usually high in fat and sugar, in a short period of time, and then feel really sick and guilty about it. They feel like they can’t stop, that they’re not in control, and it causes significant psychological distress.

The research team analysed almost 200 scientific studies into the effects of binge-like eating patterns in animals, to identify the behavioural and physiological impacts. The paper was recently published in Neuroscience and Biobehavioural Reviews.

Animal models are used to study binge eating because it is difficult to determine causality in human studies. Animals are trained to binge eat by giving them access to high-fat, high-sugar foods only for short, limited periods.

“If you give an animal such as a rat free access to high-fat, high-sugar food, it will eat the food continuously throughout the day, and that’s not bingeing. But if they only have access to it for an hour, they will learn to maximise the time and binge eat,” Dr Rehn said.

The study found that binge-like eating patterns increased motivation to seek out high-fat, high-sugar foods even though the pleasure from eating them didn’t increase.

“This suggests a dissociation between ‘wanting’ and ‘liking’. The food becomes more compelling, but not necessarily more enjoyable. This could help explain why people continue to binge even when they no longer enjoy the food itself – and why stopping can be so difficult,” Dr Mike Kendig, a co-author on this publication said.  

The review also found that animals with a history of binge eating were more likely to persist in food-seeking behaviours, even under stress which normally reduces eating. This seems to happen because the body’s stress response is blunted after eating high-fat and high-sugar foods over a long period, which has also been found in people living with binge-eating disorder.

“Anxiety and stress often co-occur with binge eating. One theory is that people who are anxious use binge eating to relieve that anxiety, but there is little evidence to suggest this from animals. Rather, the animal evidence suggests that binge eating might increase the chance that you’ll overeat the next time you’re stressed.”

While most of the animal studies did not show weight gain on the binge eating pattern, there were still metabolic consequences such as greater fat mass and higher triglyceride levels, and changes to appetite hormones, in ways that mirror early stages of metabolic disease.

For policymakers, educators and parents, the findings raise concerns about how readily available and heavily marketed these foods are, especially to young people.

“There’s a role for public policy in managing how these highly processed products are promoted,” Dr Rehn said. “The more we understand how they are impacting our health, the more urgent it becomes to address these unintended effects.”

“It’s important that we don’t just think about how our diet affects our physical health, but also about how it can change our brain and behaviour. We need to be careful with our food choices,” Dr Rehn said.

“The encouraging news is that this research empowers us to make informed decisions about what and how we eat to support both our mental and physical wellbeing. By understanding how different foods influence our mood, energy, and cognitive function, we can develop a more balanced relationship with eating.”