Likelihood of becoming obese 'set by brain cells in the womb'

Published on Monday 2 August 2010 14:58

OBESITY is fixed in the developing brains of babies before they are born, according to a new study.

Researchers found that certain cells in the brain were able to control when someone felt full and also when to direct the body to start burning calories.

In some people it appears that these brain cells - known as neurons - develop in such a way that makes it more likely they will become obese and find it harder than others to lose weight.

It is now hoped the findings could help lead to a new target for treatments to tackle obesity in the future.

Researcher Tamas Horvath and colleagues from Yale School of Medicine in the United States believe that differences in the brain could explain why two people can eat the same high-fat, high-calorie diet, with one becoming obese and the other remaining slim.

The team, writing in the journal Proceedings of the National Academy of Sciences, looked at obesity in rats bred so the scientists knew which would be more vulnerable to obesity brought on by a high-calorie diet.

Prof Horvath said the animals that became obese already had a significant difference in the "feeding centre" of the brain - the area which controls appetite and feeding habits.

They found that neurons that are supposed to signal when the rat had eaten enough and when to burn calories were much more sluggish in the obese rats because they were inhibited by other cells in the brain.

But in the animals that were resistant to obesity, the neurons signalling when they were full were much more active and ready to signal to the rest of the brain and other tissues when enough food had been consumed.

Prof Horvath said: "It appears that this base wiring of the brain is a determinant of one's vulnerability to develop obesity.

"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."

Prof Horvath also highlighted other unwanted consequences of these brain mechanisms.

"Those who are vulnerable to diet-induced obesity also develop a brain inflammation, while those who are resistant do not," he said.

"This emerging inflammatory response in the brain may also explain why those who once developed obesity have a harder time losing weight."

Experts agree that genetic factors alone cannot explain the surge in obesity in society, leading researchers to try to determine what might underpin the vulnerability to weight gain, such as events that happen in the womb.

Prof Horvath said: "The emerging view is that besides genetics, maternal impact on the developing brain is likely to be critical to imprint these feeding circuits thereby determining one's vulnerability or resistance to obesity."

However, Tam Fry, chairman of the Child Growth Foundation and a member of the National Obesity Forum, said people should not think there is no point trying to lose weight because it was down to factors beyond their control.

"The brain element in this process is for real," he said. "What a lot of people are trying to do is come up with a drug that will affect this process."

But he added: "The really important thing is that nobody should get the impression that anything like genetics or this new research should give them carte blanche to go out and eat whatever they want."