Gene mutations make people hungry for fatty foods

MCR4 mutation causes sufferers to eat more fat but less sugar
Is there really a gene mutation that increases the appetite for fatty foods? Researchers have now found just such a mutation. Affected people seem to consume less sugary foods at the same time.

Scientists from the internationally recognized University of Cambridge in Great Britain found that a rare gene mutation has a massive impact on our diet. People with such a gene mutation eat fatty foods much more often. The doctors published the results of their study in the journal "Nature Communications".

Doctors examine the eating habits of people with a gene mutation
For their investigation, the scientists tested the eating habits of subjects on a so-called all-you-can-eat buffet. It quickly became clear that people with a specific gene mutation were consuming more fatty foods, the authors say. In general, of course, many people often enjoy fatty foods. But there is a mutation of the so-called melanocortin-4 receptor (MCR4), which leads to an additional increase in consumption of fatty foods. This also happens when the fat content of the food is completely hidden, the doctors add.

Our brain can recognize the nutritional content of food without prior knowledge
If we can closely control the appearance and taste of food, our brains will be able to estimate the nutrient content, explains Professor Sadaf Farooqi of the University of Cambridge in a press release. The researchers recruited 54 subjects for their small study. These then took part in an Indian chicken curry (Chicken Korma). Of the participants, 20 were lean, 20 of the subjects suffered from obesity without an MCR4 gene mutation and 14 were obese with a corresponding mutation.

Defect affects the saturation signals in our brain
According to the researchers, about one in a hundred obese people suffer from the gene mutation. This defect in the MC4R gene often affects the weight of those affected. The defect means that saturation signals in the brain cannot be processed properly, the authors explain.

Subjects must perform taste tests
During the examination, the participants were offered a taste test of three different chicken dishes. The three dishes were previously manipulated to look and taste the same, the experts explain. In reality, however, it was a low-fat, a medium-fat and a high-fat version of the same dish. The fat content of the dishes provided 20 percent, 40 percent or 60 percent of the calories.

MC4R gene mutation allows subjects to eat more high-fat food
After tasting, all participants were free to serve themselves and eat as much as they wanted. Each group consumed approximately the same amount of food, the researchers say. However, participants with an MC4R gene mutation consumed almost twice as much of the high-fat dish compared to the slim participants. 65 percent also ate more from the dish than the obese group.

The second attempt tests the effects on sugar consumption
In a second experiment, all participants in the three groups had to choose between three different desserts. All desserts were identical in appearance, but contained different sugar levels.

Mutation affects the appetite for carbohydrates and fats
The lean and obese participants preferred the dessert with the highest sugar content. The MC4R group consumed less of all desserts compared to the lean and the other obese participants. The scientists already knew that such a gene mutation was more likely to lead to obesity. However, this study revealed for the first time that the mutation specifically affects the appetite for carbohydrates and fat.

MCR4 defect a useful survival mechanism from the past?
Nowadays, the MCR4 defect is a rather useless (and harmful) mutation for humans, the authors explain. In our primitive past, this gene mutation could have been the engine for a search for high-fat foods. Back then, this would have been a very useful survival mechanism, the researchers say.

Fat provides many calories and is easy to store
If there is little food, we need to be able to store energy when needed. Fat provides twice as many calories per gram as carbohydrates or protein and can easily be stored in our body, says Farooqi. While the study was very small, if the results can be replicated in larger research, we hope to be able to better understand the causes of obesity, the researchers concluded. (as)

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