Saturated fat urges the brain to overeat: Study

Researchers from the University of Texas Southwestern Medical Centre (UTSMC) suggests that the fat from certain foods we consume makes its way into the brain.

Once there, the fat molecules urge the brain to keep eating, overriding the appetite-suppressing signals from leptin and insulin, hormones that regulate weight.

The researchers found that one type of fat, palmitic acid -- a saturated fatty acid prevalent in beef, butter, cheese and milk, prompts the brain to let the body eat more.

Assistant Professor of Internal Medicine Dr. Deborah Clegg, the senior author of the study said, “Normally, our body is primed to say when we've had enough, but that doesn't always happen when we're eating something good.”

Study conducted on mice and rats
The study was performed on rats and mice in the lab. The animals were fed with the same amount of calories of different types of fat - palmitic acid, monounsaturated fatty acid and oleic acid.

The various types of fat were either injected directly into the brain through the carotid artery, or the rodents were administered the fat through a stomach tube three times a day.

Observations by scientists
Dr. Clegg said, “We found that the palmitic acid specifically reduced the ability of leptin and insulin to activate their intracellular signaling cascades. The oleic fat did not do this. The action was very specific to palmitic acid, which is very high in foods that are rich in saturated-fat.”

She further added, “What we've shown in this study is that someone's entire brain chemistry can change in a very short period of time. Our findings suggest that when you eat something high in fat, your brain gets 'hit' with the fatty acids, and you become resistant to insulin and leptin. Since you're not being told by the brain to stop eating, you overeat.”

The scientists noted that the effects of the saturated fat in the animals lingers up to three days, which perhaps explains why a diet high on fat during weekends makes one hungrier than normal on Monday.

Dr Clegg said the study reinforces the need for individuals to limit their saturated fat intake.

Results of the study are published in the September issue of The Journal of Clinical Investigation.