A Possible Cause for Obesity
(Ivanhoe Newswire) -- It seems a naturally occurring peptide that contributes to weight maintenance is reduced in obese people compared with thin people. Doctors from London report obese patients have lower levels of the fragment peptide YY3-36, otherwise known as PYY. They also found that obese patients are not resistant to its effects.
The gut hormone PYY suppresses appetite and decreases food intake when given to people without weight problems. Similar to the hormone leptin, PYY works with the hypothalamus to reduce food intake. Previous studies show obese people are resistant to the effects of leptin. The purpose of this study was to determine if obese individuals are also resistant to the effects of PYY. Researchers enrolled 12 obese people and 12 lean people in the study.
In the placebo-controlled study, a buffet lunch was served after the subjects received an infusion of PYY. The researchers write, "Caloric intake was decreased by 30 percent in the obese subjects and 31 percent in the lean subjects." Over 24 hours, there was also a decrease in the caloric intake. It was the same in both obese and thin patients.
The researchers found natural levels of PYY were lower in obese people than others, but by infusing the hormone, they were able to reduce the appetite and calorie consumption of obese people. They suggest this might play a part in obesity and even "may be a useful treatment for obesity." However, further research will be necessary to confirm that. It is still unclear whether low levels of PYY cause obesity or are a result of obesity.
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SOURCE: New England Journal of Medicine, 2003;349:941-948
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