Scientists discover a gene variant that makes you less adverse to fatty foods and determine the areas of the brain that make sleep-deprived individuals ravenous.

The science of hunger is an ever-evolving field. New studies are constantly being published about what it is that makes us crave certain foods, and what makes us crave them when we do. Two recently published studies, one in the Journal of Clinical Endocrinology and Metabolism and the other in the Journal of Lipid Research, have deepened our knowledge of the way we experience hunger.

The first, a study exploring sleep deprivation and hunger, identified the specific areas of the brain that increase hunger in sleep-deprived individuals. The second study determined that a variant in the CD36 gene makes certain people less sensitive to the presence of fat in foods.

In 2004, scientists found that chronic sleep deprivation increases the overall levels of hunger experienced by an individual. Last week European scientists, led by Christian Benedict from Uppsala University in Sweden, announced that they had managed to identify the areas of the brain responsible for the ravenous feeling students get after pulling “all-nighters”.

In this study, 12 healthy males in their twenties were subject to both a period of sleep deprivation and a period of regular sleep lasting 7 hours.  By showing the sleep-deprived subjects pictures of food, the scientists were able to determine that the men were experiencing activity levels greater than normal in the right anterior cingulate cortex using an fMRI machine. This portion of the brain is known to play an important role in evaluating representations of food, and is associated with the sensation of reward that comes from eating.

Previous studies have shown that clinically obese individuals tend to have higher levels of activity in this region of the brain relative to people of average weight. Sleeping less therefore causes your brain to react the same way as it does in the highly overweight.

In addition, the tired participants were 12 per cent more likely to find pictures of food appetizing than when they had slept for 7 hours, despite having the same plasma glucose concentrations in their blood. This means that although the participants did not have lower blood sugar levels than on mornings when they had slept well, they still felt as though they did and reacted to the pictures of food accordingly.

In the second study, Washington University researchers looked at oral sensitivity to foods with a high fat content in 21 clinically obese individuals. They found that certain participants had lower oral detection thresholds for fatty foods, so they were less likely to be put off by foods with high fat contents than the average population.

People with this specific CD36 gene variant produce lower than average levels of CD36 proteins, causing them to have higher affinities for fatty foods. The scientists, led by Dr. Marta Yanina Pepino, believe that this variant makes one less sensitive to the presence of fat in food, thus making it necessary for such an individual to eat more fats in order to satisfy his or her cravings. It is estimated that 20 per cent of people have this variant.

The participants who made more CD36 protein, however, were better able to detect the presence of fat in food, making them less likely to eat fatty foods. Those who made the most were eight times more sensitive to the presence of fat than those who made only half that amount of protein.

Although this genetic difference contributes to rising obesity levels, we cannot put all the blame on genetic variations. The Washington University scientists have acknowledged that a higher intake of fatty foods can result in lower CD36 protein production, meaning that those who follow a high-fat diet end up becoming less sensitive to the presence of fat in food, so the difference in CD36 protein production can be both genetic and acquired.

Ordinarily, a journalist would end this article by telling you to eat well, get plenty of exercise and sleep in order to remain healthy. However, being a student myself, I know how hard following these “simple” precepts can be. Instead, I will simply tell you that if you feel unhealthy, start with small, incremental changes in your lifestyle, that may or may not include naps, vegetables, lean proteins, whole grains, long walks outside, and homemade baking sessions with friends, just for good measure.

Arielle blogs about science at www.salamanderhours.com

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