According to research from the University of Adelaide, which was funded by the National Health and Medical Research Council, this could be a key reason why people who lose weight on a diet eventually put that weight back on.
The study, which was published in the International Journal of Obesity, saw researchers investigate and find that the nerves in the stomach that signal fullness appear to be desensitised after long-term consumption of a high-fat diet.
More food needed
“The stomach's nerve response does not return to normal upon return to a normal diet,” says Amanda Page, study leader and Associate Professor from the University's Nerve-Gut Research Laboratory. “This means you would need to eat more food before you felt the same degree of fullness as a healthy individual.”
Page pointed out that 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 desensitises the nerves that detect fullness,” she said.
According to Page, these two mechanisms combined mean that obese people need to eat more to feel full, which in turn continues their cycle of obesity. “This has very strong implications for obese people, those trying to lose weight, and those who are trying to maintain their weight loss.”
Unsure of long-term
Page admitted that they are not yet sure whether this effect is permanent or just long-lasting. “We know that only about 5% of people on diets are able to maintain their weight loss, and that most other people put all of that weight back on in two years.”
“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 resetting itself to normal.”
International Journal of Obesity
S J Kentish, T A O'Donnell, C L Frisby, H Li, G A Wittert and A J Page