Whether you’re obese or not, going on a diet and keeping the weight off is often a struggle, as fighting temptation or maintaining a regular exercise schedule can become difficult. But for people who are considered obese, these struggles may become even more difficult because, in obese people, the stomach mechanisms that notify the brain that the person is full stop working after consuming too many fatty foods. Worsening the ordeal, these mechanisms don’t return to their normal state once a diet is implemented, according to a new study.

The study, which involved mice, looked at how eating a high-fat diet affected eventual weight loss. The researchers found significant effects in the hormone leptin, which is a mediator of long-term regulation of energy balance and helps to suppress food intake. They found that when mice ate high-fat diets, leptin desensitized nerves that send signals to the brain indicating fullness. That means that “obese people need to eat more to feel full, which in turn continues their cycle of obesity,” lead author Amanda Page, an associate professor at the University of Adelaide’s Nerve-Gut Research Laboratory, said in a statement.

When it came to the mice, researchers split them into three groups and experimented on them for 24 weeks: one group was fed a standard diet, another was fed a high-fat diet, and the last was fed a high-fat diet for the first 12 weeks and a standard diet for the remaining 12 weeks. The team found that leptin receptors in the stomach remained desensitized in the group that switched to a standard diet for 12 weeks.

“Unfortunately, our results show that the nerves in the stomach remain desensitized to fullness after weight loss has been achieved,” Page said in the statement. The results of this study could help explain why so many people who go on diets end up reverting back to their fatty-food consuming ways, the researchers said.

More than one-third of Americans are considered obese, according to the Centers for Disease Control and Prevention (CDC). The CDC says that knowing your body mass index (BMI), figuring out how to achieve and maintain a healthy weight, and getting regular physical activity can help fight obesity. But above all else, having realistic goals and ambition toward attaining them is what will make it easier.

Page says that the next steps in their research is to see how long the effect lasts and to examine “whether there is any way — chemical or otherwise — to trick the stomach into resetting itself to normal.”

 

Source: Kentish S, O’Donnell T, Frisby C, et al. Altered gastric vagal mechanosensitivity in diet-induced obesity persists on return to normal chow and is accompanied by increased food intake. International Journal of Obesity. 2013.