Health & Medicine

Obese Stomachs May Doom Future Diets: Why We Can't Keep Off the Pounds

Catherine Griffin
First Posted: Sep 17, 2013 11:10 AM EDT

There may be a reason why you can't keep off the pounds. The way a stomach detects and tells our brains how full we are becomes damaged when we're obese. Now, scientists have discovered that this doesn't return to normal once we lose the weight. The findings could be key to understanding why people's weight fluctuates even after they shed the pounds.

"We know that only about 5 percent of people on diets are able to maintain their weight loss, and most people who've been on a diet put all of that weight back on within two years," said Amanda Page, one of the researchers, in a news release.

In order to find out exactly why this was, the researchers investigated the impact of a high-fat diet on the gut's ability to signal fullness. They found that the nerves in the stomach that signal fullness to the brain are desensitized after long-term consumption of a high-fat diet. Yet more importantly, these nerves don't return to normal even after losing weight.

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

In other words, formerly obese people need to eat more in order to feel as if they're full. This has enormous implications for those trying to lose weight and, in particular, for those trying to maintain their weight loss.

"More research is needed to determine how long the effect lasts, and whether there is any way-chemical or otherwise-to trick the stomach into resettling itself to normal," said Page.

The findings are published in the International Journal of Obesity.

See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone

More on SCIENCEwr