People who carry a particular gene have an increased preference for high fat food, but a decreased preference for sugary foods, a new Cambridge study found. The study is the first one to draw a connection between our genes and food preference and it can also provide insight to obesity.

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Back in the (prehistoric) day, humans lived in extremely different conditions than we do today. Shelter was almost a luxury and food wasn’t readily available. In those days, if you were lucky enough to find some food (some fruit trees or an animal), you would eat as much as you can. Ironically, our brains are wired in much the same way as they were back then – if we start eating, there’s a good chance we eat way more than we need because subconsciously, our brain is trying to stockpile energy. This is why most people find fatty or sugary foods extremely attractive – because they have a lot of embedded energy. This is also why these foods make us fat.

But biology might also play a role in our food preference. In a study published today in the journal Nature Communications, researchers at the University of Cambridge gave participants an all-you-can-eat buffet of chicken korma – a popular type of curry. They gave participants three curry options, which looked and tasted the same but had different fat contents (20% – low, 40% – medium and 60% – high). The participants tasted from all the three kormas and then ate freely, whatever they wanted.

Researchers then split the participants into three categories: lean, obese, and obese because they have a defect in a gene called MC4R. They found that individuals with defective MC4R ate almost double the amount of high fat korma than lean individuals ate (95%) and even than other obese people (65%). But the surprise came in the next experiment.

In the second part, participants were given Eton mess, a popular desert which includes whipped cream, strawberries, and meringue. Again, the design was similar and the deserts had different sugar contents (8%, 26% and 54%). Paradoxically, the results were the exact opposite of the curry experiment: lean people enjoyed the desert with the most sugar while obese people with a defective MC4R gene preferred the one with the least sugar. People who prefer high-fat foods also prefer low-sugar foods, and people who prefer low-fat foods prefer high-sugar foods. Of course, this is a general correlation, not a fixed rule that applies for everyone.

Professor Sadaf Farooqi, who led the research team, says:

“Our work shows that even if you tightly control the appearance and taste of food, our brains can detect the nutrient content. Most of the time we eat foods that are both high in fat and high in sugar. 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.”

She believes that both humans and animals evolved in a way that makes them more resilient to famine, and thus there is a genetic preference for some types of food.

“When there is not much food around, we need energy that can be stored and accessed when needed: fat delivers twice as many calories per gram as carbohydrates or protein and can be readily stored in our bodies,” she explains. “As such, having a pathway that tells you to eat more fat at the expense of sugar, which we can only store to a limited extent in the body, would be a very useful way of defending against starvation.”

More experiments are needed to back these conclusions up, but in the meantime, one thing’s for sure: I’d really like to have a chicken korma.

Journal Reference: Agatha A. van der Klaauw, Julia M. Keogh, Elana Henning, Cheryl Stephenson, Sarah Kelway, Victoria M. Trowse, Naresh Subramanian, Stephen O’Rahilly, Paul C. Fletcher, I. Sadaf Farooqi. Divergent effects of central melanocortin signalling on fat and sucrose preference in humans.Nature Communications, 2016; 7: 13055 DOI:10.1038/NCOMMS13055

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