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Crave Fatty Foods? You May Have a Rare Gene Mutation

In one of tastiest scientific experiments on record, researchers held an all-you-can-eat buffet to determine how a rare gene mutation affects food cravings. They found that people with the mutation were more likely by far to crave fatty food, and much less likely than others to eat sugary food. The mutation occurs in the melanocortin-4 receptor (MCR4) gene.

Lead researcher Sadaf Farooqi of England’s Cambridge University says:

Our work shows that even if you tightly control the appearance and taste of food, our brains can detect the nutrient content.

Farooqi and her team enlisted 54 subjects to participate in their chicken korma buffet, which featured a popular, creamy curry dish. Twenty of the subjects were described as lean, 20 as obese, and 14 were obese with the gene mutation.

The scientists say approximately one in 100 obese people have the defect in the MC4R gene, which contributes to weight gain. Because of the defect, the brain fails to recognize satiety signals.

The researchers offered each of the participants a taste test of three different chicken korma recipes. The curry dishes were prepared to look and taste just the same, but they were actually low, medium and high-fat versions of the dish. The fat content was either 20 percent, 40 percent, or 60 percent of the calories.

The subjects sampled each recipe, then were invited to serve themselves and eat freely of any version they preferred. Each group ate approximately the same amount of food, but the participants with the gene mutation ate nearly twice as much of the high-fat dish as did the lean group (by 95 percent) and 65 percent more than the obese group.

While the gene mutation seems to make people prefer fat, it has the positive effect of reducing sugar craving. A second experiment was conducted using the same three groups of participants. They were asked to choose from desserts that appeared identical. The dessert is made from strawberries, whipped cream and meringue, and is called Eton mess.

Again, they were offered three versions of the recipe. One had a low sugar content, another medium, and the third a high sugar content. In this experiment, the lean participants showed a preference for the high-sugar version, but the MC4R participants reported liking that version the least of the three groups.

Farooqi says:

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 explains the possible evolutionary purpose of the gene mutation:

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.

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.

This study is just one of the many that are being conducted to help scientists understand the issue of obesity, and how to treat it.

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Category: Food, Weight Loss

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