Photo: sleepyneko, Flickr

Tough day at the office? Nothing a pint of Häagen-Dazs chocolate-chocolate chip can't fix, right? Think again. A new study suggests that foods high in saturated fat can trick our bodies into eating more -- and that the effect may last for up to three days.

The UT Southwestern Medical Center study, published in the Journal of Clinical Investigation, found that fat from certain foods heads straight to the brain. The fat molecules, in turn, prompt the brain to send signals to the body's cells to ignore appetite-suppressing signals from insulin and leptin, hormones involved in food intake and body-weight regulation.

We already know that saturated fat raises cholesterol levels and increases our risk of heart disease, but these findings indicate that fat intake also disrupts weight-regulating hormone activity. Palmitic acid, a saturated fat found in beef, butter, cheese and milk, appears to be the worst offender.

The study was conducted on rats and mice, but researchers believe that the results strengthen existing dietary recommendations to limit saturated fat intake. (Current guidelines recommend keeping total fat between 20 to 35 percent of calories with less than 10 percent of calories from saturated fats.)

"With respect to applying to humans, I can only make an educated guess, but I believe that when humans eat diets high in saturated fat, and palmitic acid in particular, hormones such as leptin, which normally regulate food intake and body weight will be less effective," says researcher Debbie Clegg. This helps explain why you wake up ravenous the morning after Thanksgiving -- all that butter and cheese is literally toying with your brain.

Here's another reason to watch the fat -- don't want too much of it going to your liver.