Some people have a defective gene that makes them crave fatty foods, according to U.K. researchers.
The University of Cambridge fed 54 volunteers a two-course meal to see how various fat content affected their eating behavior. Scientists found that people with a rare defective MC4R gene -- linked to obesity -- preferred the high-fat offerings and ate more of them than the volunteers without the gene.
About one in 1,000 people carries a defective version of MC4R, which controls hunger and appetite and affects how we burn calories, according to the BBC. Mutations in the gene are a common cause of severe obesity in families.
Researchers for the study, published in the Nature Communications journal, created three versions of both chicken korma (a South Asian dish of chicken with yogurt sauce) and a strawberries-and-cream dessert. Each version of the chicken dish varied in fat content, while each dessert had a different amount of sugar.
Volunteers with defective MC4R ate much more of the high-fat chicken korma than the lean and obese volunteers without the defect. As for the dessert, the defective MC4R carriers were the only ones who didn't opt for the high-sugar version.
This would suggest that MC4R makes people value fat over sugar. The results make sense, researchers think, because people likely developed hunger genes to eat more and store fat during times of famine.
"Most of the time we eat foods that are both high in fat and high in sugar," said lead researcher Sadaf Farooqi.
"By carefully testing these nutrients separately in this study, and by testing a relatively rare group of people with the defective MC4R gene, we were able to show that specific brain pathways can modulate food preference."
When your brain prompts you to choose foods that are high in fat and low in sugar, it's defending the body from starvation, Farooqi said. Having a defect in MC4R, though, can make hunger insatiable.
So next time you want fried chicken after just having eaten pizza, you've got a valid question to ask yourself: Do you have a defective MC4R gene? Or do you need to get your cravings in check?