Is obesity impacting your brain forever? Experts say yes

A new study has found that obesity is likely to damage the ability of the brain to recognise the sensation of fullness of the stomach and to detect satisfaction after consuming sugars and fats.

The study emphasised the changes in the brain may last forever even after a significant amount of weight is lost by people who are considered medically obese, which further explained why a lot of people regain their weight after losing it.

“There was no sign of reversibility — the brains of people with obesity continued to lack the chemical responses that tell the body, ‘OK, you ate enough,’” stated Dr Caroline Apovian, who works as a professor of medicine at Harvard Medical School. He is also the co-director of the Centre for Weight Management and Wellness at Brigham and Women’s Hospital in Boston.

“This study captures why obesity is a disease — there are actual changes to the brain,” stated Apovian, who was not part of the group that carried out the study.

“The study is very rigorous and quite comprehensive,” stated Dr I Sadaf Farooqi, who is a professor of metabolism and medicine at the University of Cambridge in the UK and was not involved in the new research.

“The way they’ve designed their study gives more confidence in the findings, adding to prior research that also found obesity causes some changes in the brain,” she added.

Clinical trial

On Monday, Nature Metabolism published the study which was done based on a controlled clinical trial involving 30 people who are considered medically obese and 30 people who have normal weight. The group of people were fed sugar carbohydrates (glucose), fats (lipids) or water (as a control). On separate days, each group of nutrients were fed to people directly into the stomach through a feeding tube.

“We wanted to bypass the mouth and focus on the gut-brain connection, to see how nutrients affect the brain independently from seeing, smelling or tasting food,” stated lead study author Dr Mireille Serlie, professor of endocrinology at Yale School of Medicine in New Haven, Connecticut.

One night before the testing, the participants were given the same meal for dinner at home and they did not consume anything till the feeding tube was in place the next morning. When either fats or sugars entered the stomach through the tube, functional magnetic resonance imaging (fMRI) and single-photon emission computed tomography (SPECT) were used by researchers to capture the response of the brains for over 30 minutes.

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“The MRI shows where neurons in the brain are using oxygen in reaction to the nutrient — that part of the brain lights up,” stated Farooqi. “The other scan measures dopamine, a hormone that is part of the reward system, which is a signal for finding something pleasurable, rewarding and motivating and then wanting that thing," he added.

In people who had normal weight, the study found evidence of brain understanding that the body had been fed when either sugars or fats were put into the stomach. Also, the levels of dopamine rose in people with normal weight which signalled that the brain's reward centres were activated. However, in medically obese people, no evidence was found of brain understanding that food has been given to the body and there was no rise in dopamine levels.

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