Love fatty food? Desire may be hard-wired

What’s your poison – fatty foods or sweet? Your answer may be swayed by your genes.

A study by UK researchers published in Nature Communications suggests that a genetic mutation that changes a receptor in the brain bestows certain food preferences.

We’re driven towards high-energy foods as an evolutionary response. Fatty foods are higher in calories than carbohydrates or protein, and the fat can be easily stored in tissue, which may explain why we love them so much.

But sweet foods are packed with energy too. So why do some people prefer fat over sugar?

Previous studies on mice showed that the genes that control melanocortin-4 receptors (MC4R) in certain brain circuits are particularly relevant to feeding.

When these genes are interrupted, mice tend to overeat and show a higher preference for fat-rich foods.

But how those receptors affect humans hadn’t been explored, so Ismaa Farooqi and her crew at the University of Cambridge decided to look into it.

Some 1 to 5% of people with severe obesity have this MC4R variation. Farooqi’s team gathered 14 such individuals and tested their food preferences in comparison to a control group, some of whom were also obese.

Participants were given meals of chicken korma with high, medium and low fat content, and asked to rate how much they liked each.

The test was then repeated with sugar-laden Eton mess desserts. The fat and sugar levels of each meal weren’t made obvious to the participants.

When asked to rate how much they liked each of the high-fat meals, all groups responded with similar levels, but the MC4R-deficient group ate significantly more of the highest-calorie meal than the other groups.

When it came to the high-sugar foods, the control participants showed a preference for the highest level of sweetness, as predicted by previous research.

The MC4R-deficient group, though, was less fond of the highest-sugar meal and consumed significantly less of all three desserts than their control counterparts.

“This is to our knowledge one of the first experimental studies to show a direct association between macronutrient preference (other than alcohol) and a specific genetic/molecular mechanism in humans,” the researchers write. 

The team believes this finding (and others like it) will be a “powerful tool” in linking the understanding of the molecular control of energy balance to the biology underpinning food preference in humans.