New research from the University of Aberdeen Rowett Institute suggests that an unhealthy diet during adolescence could have long‑lasting effects on how the brain makes decisions about food – even after returning to a healthy diet.
Adolescence is a critical period for brain development, yet growing numbers of young people are living with overweight or obesity during this time. While the physical health impacts of poor diet are well known, much less is understood about how early‑life nutrition affects decision‑making later in life.
Using a mouse model, researchers from the Rowett Institute and the University of Sussex, found that consuming a high‑fat diet during the teenage years led to more rigid, habitual food‑seeking behaviour in adulthood. The study also revealed important differences between males and females, highlighting the need to consider sex differences in brain and diet research.
In the study, which is published in Neuropsychopharmacology, mice were fed a high‑fat diet during adolescence. Once they reached adulthood, the animals were switched back to a healthy diet and trained to perform a simple task to obtain food. Researchers then tested how flexibly the mice adapted their behaviour when the situation changed – for example, when the food was no longer needed or was freely available.
Unlike control mice, those that had eaten a high‑fat diet during adolescence continued to seek out food even when it was no longer beneficial to do so. This type of behaviour is known as habitual behaviour and reflects reduced cognitive flexibility – the ability to adapt decisions based on new information.
Dr Fabien Naneix
Dr Fabien Naneix, who led the study, said: “Our results suggest that what you eat as a teenager may influence how you make decisions about food later in life, even if your diet improves as an adult.
“We also found that males and females were affected in different ways, which reinforces how important it is to study both sexes in nutrition and brain research.
"In our study, males correctly adapted when the food was freely available but continue to perform the task even when the food was not desired anymore. Interestingly the opposite pattern was observed in females. Even more interesting is that these cognitive deficits observed in females were not especially associated with weight gain. These mice were comparable to the control mice in term of body weight."
The findings suggest that early exposure to unhealthy diets may shape how the brain regulates food‑related decisions, making unhealthy habits harder to break over time. This could help explain why long‑term weight loss is challenging for many people and why prevention strategies during childhood and adolescence are so important.
Dr Kate Peters from the University of Sussex added: “"Our data highlight how adolescent eating habits can have long-term effects on decision making, and we are excited to explore how these habits affect different parts of the brain in our future work."
Dr Riaz Bhunnoo, Associate Director at the UKRI-Biotechnology and Biological Sciences Research Council, said: “This study offers valuable insight into how dietary habits during adolescence can shape brain function and behaviour later in life. By identifying how overconsumption of sugar and energy-rich foods can alter dopamine signalling and influence food choices, it strengthens our understanding of the biological drivers of obesity.
“BBSRC is proud to support research like this, which is helping to build the evidence needed to inform healthier lifestyles and improve long-term public health.”
The study was funded by the Academy of Medical Sciences, BBSRC, Tenovus Scotland, the Royal Society of Edinburgh and the Leverhulme Trust.