Most people start to feel full about 10 minutes after they begin eating, but obese people experience a delay in that message being transmitted to their brains.
The finding suggests that the inability to feel satisfied while eating could perpetuate obesity, making treatment difficult. The study appears in the February issue of the Psychiatric Annals.
Using neuroimaging to scan the brains of 10 obese and 20 normal-weight adults, the researchers pinpointed when the brain responds to changing hormone levels in the body that signal a person has had enough to eat.
Each study volunteer received about 350 scans over the course of 35 minutes. They were given glucose intravenously after the first five minutes to trigger the body's food response.
Those responses to food in the hypothalamic region of the obese peoples' brains were weaker and significantly delayed (4 to 9 minutes longer), compared to the responses of the normal-weight people.
Possible ways to counter this slow response to feeling full in obese people may include behavioral changes, such as eating only when hungry, slowing the pace of meals, and learning to enjoy smaller food portions.
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