Recent research reveals structural differences in the hypothalamus of obese people

Obesity is far from just being a cosmetic concern punctuated by the perception of body image – it is primarily a medical problem that heavily increases the risk of developing severe diseases and health problems.

Current estimations suggest that over one billion people worldwide are either overweight or obese, and these colossal numbers continue to grow in a horrifying fashion.

For instance, the World Obesity Federation's 2023 atlas predicts that over half of the world's population will be obese or overweight by the year 2035.

But what about the science behind obesity? Specifically, is there a more neurological cause for the over-consumption of food?

Well, according to the results of a recent study carried out by Cambridge scientists, an important role towards obesity may be played by a certain, deep-rooted function within the human brain.

And that function is the hypothalamus.

In Layman's terms, the almond-sized hypothalamus is involved in controlling appetite, with its secondary functions being to produce hormones for regulating sleep, body temperature and heart rate.

During the study, researchers found that the hypothalamus in the brains of overweight and obese patients was different to those who were at a healthy weight.

There are many factors that influence how much we eat, along with the types of food we eat, which include our genetics, hormone regulation, and, of course, the environment that we live in. Although, what happens in our brains to tell us that we are hungry or full is relatively unclear.

That being said, previous studies, particularly those using animals, have heavily suggested that the hypothalamus plays a crucial role in this function for eating.

"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."

Dr Stephanie Brown, Department of Psychiatry at the University of Cambridge.

Despite this difficulty, Dr Brown and her colleagues analysed the MRI brain scans taken from 1,351 young adults across a range of body mass index (BMI) scores.

Subsequently, the team discovered that the overall volume of the hypothalamus was significantly larger in the overweight/obese groups of young adults. The team even found a distinctive relationship between BMI and volume of the hypothalamus.

While the precise meaning of this finding is unclear, one possibility of the result is that this change in the structure of the hypothalamus relates to inflammation.

Previous animal studies have shown that a high-fat diet can cause inflammation within the hypothalamus, which, in turn, prompts a resistance to insulin, followed by obesity.

For example, it took just three days of a fat-rich diet in mice to cause this inflammation.

Dr Brown commented: "If what we see in mice is the case in people, then eating a high-fat diet could trigger inflammation of our appetite control centre."

She continued: "Over time, this would change our ability to tell when we've eaten enough and to how our body processes blood sugar, leading us to put on weight."

The Cambridge team suggest that this inflammation could explain why the hypothalamus is larger in obese individuals.

Professor Paul Fletcher, also from the Department of Psychiatry at Cambridge, said: "The last two decades have given us important insights about appetite control and how it may be altered in obesity. Metabolic researchers at Cambridge have played a leading role in this."

The professor concluded by stating that with this new approach for analysing brain scans in humans, medical experts can subsequently gain a better understanding of obesity.