Brain's appetite control centre different for persons with obesity, finds Cambridge University study

LONDON: University of Cambridge scientists have found that the hypothalamus, a key region of the brain involved in controlling appetite, is different in the brains of people who are overweight and people with obesity when compared to people who are of healthy weight, said a study released on Tuesday.

The researchers say their findings add further evidence to the relevance of brain structure to weight and food consumption. Current estimates suggest that over 1.9 billion people worldwide are either overweight or obese, which increases an individual’s risk of developing a number of health problems, including type 2 diabetes, heart disease and stroke, cancer and poorer mental health.

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“Although we know the hypothalamus is important for determining how much we eat, we actually have very little direct information about this brain region in living humans. That’s because it is very small and hard to make out on traditional MRI brain scans,” said Dr Stephanie Brown from the department of psychiatry and Lucy Cavendish College, University of Cambridge, and the author of the study.

A large number of factors influence how much we eat and the types of food we eat, including our genetics, hormone regulation, and the environment in which we live. What happens in our brains to tell us that we are hungry or full is not entirely clear, though studies have shown that the hypothalamus, a small region of the brain about the size of an almond, plays an important role. The majority of evidence for the role of the hypothalamus in appetite regulation comes from animal studies.

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These show that there are complex interacting pathways within the hypothalamus, with different cell populations acting together to tell us when we are hungry or full. To get around this, Brown and colleagues used an algorithm developed using machine learning to analyse MRI brain scans taken from 1,351 young adults across a range of BMI scores, looking for differences in the hypothalamus when comparing individuals who are underweight, healthy weight, overweight and living with obesity.

In the study published in ‘Neuroimage: Clinical’, the team found that the overall volume of the hypothalamus was significantly larger in the overweight and obese groups of young adults. In fact, the team found a significant relationship between volume of the hypothalamus and body-mass index (BMI). These volume differences were most apparent in those sub-regions of the hypothalamus that control appetite through the release of hormones to balance hunger and fullness.