Obesity Desensitizes Nerves in Gut, May Explain Weight Gain After Dieting

Researchers from the University of Adelaide in Australia suggest that damage to the stomach caused by obesity will prevent it from returning to a normal size, even if a person loses weight.

The study authors contend that this stomach damage could be a key reason why people put weight back on even after a successfully losing weight on a diet.

Lead study author Amanda Page from the University's Nerve-Gut Research Laboratory and her colleagues investigated the negative impacts of a high-fat diet on the gut's ability to tell the body it is full and whether those changes would correct themselves back to normal by losing weight. Their research shows that among the many ill effects of a high-fat diet is that nerves in the stomach appear to become desensitized after long-term consumption of a high fat diet.

"The stomach's nerve response does not return to normal upon return to a normal diet. This means you would need to eat more food before you felt the same degree of fullness as a healthy individual," Page said.

"A hormone in the body, leptin, known to regulate food intake, can also change the sensitivity of the nerves in the stomach that signal fullness. In normal conditions, leptin acts to stop food intake. However, in the stomach in high-fat diet induced obesity, leptin further desensitizes the nerves that detect fullness," she said. "These two mechanisms combined mean that obese people need to eat more to feel full, which in turn continues their cycle of obesity."

Page said the study has "very strong implications for obese people, those trying to lose weight, and those who are trying to maintain their weight loss."

"Unfortunately, our results show that the nerves in the stomach remain desensitized to fullness after weight loss has been achieved," Page said, adding that more research is needed to determine if anything can be done to trick the stomach into resetting itself to normal.

Page and her colleagues' research is published in the International Journal of Obesity.