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| Obesity may damage the brain’s ability to recognize the sensation of fullness and be satisfied after eating fats and sugars, a new study found. |
| Further, those brain changes may last even after people considered medically obese lose a significant amount of weight — possibly explaining why many people often regain the pounds they lose. |
| As defined medically, people with obesity have a body mass index, or BMI, of over 30, while normal weight is a BMI of between 18 and 25. |
| The study, published Monday in Nature Metabolism, was a controlled clinical trial in which 30 people considered to be medically obese and 30 people of normal weight were fed sugar carbohydrates (glucose), fats (lipids) or water (as a control). Each group of nutrients were fed directly into the stomach via a feeding tube on separate days. |
| The night before the testing, all 60 study participants had the same meal for dinner at home and did not eat again until the feeding tube was in place the next morning. As either sugars or fats entered the stomach via the tube, researchers used functional magnetic resonance imaging (fMRI) and single-photon emission computed tomography (SPECT) to capture the brain’s response over 30 minutes. |
| In people with normal weight, the study found brain signals in the striatum slowed when either sugars or fats were put into the digestive system — evidence that the brain recognized the body had been fed. |
| At the same time, levels of dopamine rose in those at normal weight, signaling that the reward centers of the brain were also activated. |
| However, when the same nutrients were given via feeding tube to people considered medically obese, brain activity did not slow, and dopamine levels did not rise. |
| Next, the study asked people with obesity to lose 10% of their body weight within three months — an amount of weight known to improve blood sugars, reset metabolism and boost overall health. |
| Tests were repeated as before — with surprising results. Losing weight did not reset the brain in people with obesity. |
| Much more research is needed to fully understand what obesity does to the brain, and if that is triggered by the fat tissue itself, the types of food eaten, or other environmental and genetic factors. |
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