The brain prods you into splurging on an extra ice-cream scoop or that second burger, practically sabotaging your efforts to get back into shape, a new study says.
Findings from a new University of Texas Southwestern Medical Centre (UTSMC) study suggest that fat from certain foods we eat makes its way to the brain. There, these fat molecules cause the brain to send messages to the body's cells, directing them to ignore the appetite-suppressing signals from leptin and insulin, hormones involved in weight regulation.
Researchers also found that one particular type of fat - palmitic acid, is particularly effective at instigating this mechanism. It is a common saturated fatty acid, occurring in butter, cheese, milk and beef.
"Normally, our body is primed to say when we've had enough, but that doesn't always happen when we're eating something good," said Deborah Clegg, assistant professor of internal medicine at UTSMC. Clegg led the study on rodents.
"What we've shown in this study is that someone's entire brain chemistry can change in a very short period of time. When you eat something high in fat, your brain gets 'hit' with the fatty acids, and you become resistant to insulin and leptin," Clegg said. "Since you're not being told by the brain to stop eating, you overeat."
In animals, the effect lasts about three days, potentially explaining why many people who splurge on Friday or Saturday say they're hungrier than normal on Monday, added Clegg.
Clegg said that even though the findings are in animals, they reinforce the common dietary recommendation that individuals limit their saturated fat intake. "It causes you to eat more," she said.
The next step, Clegg averred, is to determine how long it takes to reverse completely the effects of short-term exposure to high-fat food.