People are fat because they struggle to recognise when they are full
Some people find it more difficult to stay slim than others because their brains are slow at recognising when they are full, a study claims.
Researchers have discovered that the different wiring means that they often overeat which leads to obesity.
The findings add to the growing evidence that it is not always your diet that leads to being overweight but also your genetic inheritance and pre-birth development of the brain.
It also explains why two people – or siblings – can consume the same high fat diet but one remains thin while the other puts on weight.
The team at Yale University found that in rats some have nerve endings which are more sluggish at signalling when your stomach is full than others.
This means that they overeat slightly at every meal and eventually this leads to obesity.
The finding published in Proceedings of the National Academy of Sciences could help explain why two people can consume the same high fat Western diet and one becomes obese and prone to diabetes while the other maintains a slim frame.
"It appears that this base wiring of the brain is a determinant of one's vulnerability to develop obesity," said Professor Tamas Horvath, a neurobiologist at Yale University.
"These observations add to the argument that it is less about personal will that makes a difference in becoming obese, and, it is more related to the connections that emerge in our brain during development."