Are you genetically inclined to be obese?
Millions of years ago, when food was often scarce and famines were regular, it was beneficial for our ancestors to be able to eat more and better store energy. One gene, in particular, FTO, developed a variant that was especially masterful at making sure humans were eating more than their fill when they had the chance.
Today, in Western society, there is no need to prepare our bodies for a famine that will never come. But unfortunately, some people still have the FTO gene variant, which changes their physiological and behavioral reactions to food.
The FTO gene:
However, this variant is not universally present in everyone. It is generally found in about 20% of white people and in over 75% of some African populations. This correlates to when some early homo sapiens left Africa and found an abundance of food in fertile Europe, while the homo sapiens who stayed in Africa still faced long periods of starvation. White people still have the FTO gene, but it has evolutionarily evolved to be a variant with a low risk of obesity.
The FTO variant causes carriers to exhibit a preference for high-fat foods, reduced satiety responsiveness after eating, and greater food intake. Other byproducts of the gene include:
Increased production (and decreased postprandial suppression) of Ghrelin, the hunger hormone
Reduced leptin sensitivity
Increased white fat
Slower metabolism secondary to leptin resistance
Impaired fat burning
All these factors contribute to a 70% higher risk of obesity for those with two alleles of the risk FTO variant. These people are genetically predisposed to prefer high-calorie, high-fat foods. And they are more likely to not feel full when they actually are. Essentially, if you have the high-risk FTO gene, you are “biologically programmed” to store fat.
Interestingly, FTO does not impact how you metabolize food or how your body regulated energy expenditure. This is good news for those with the FTO variant. The FTO variant does not make you obese, it is your behavior in acquiescing to what this gene is telling you to do that is causing you to be obese. This is proven true in Africans with the variant. While they have the same predisposition for obesity, their diet and exercise prevent them from have a high BMI.
Exercise & the FTO gene
Research comparing people with and without the FTO risk variant demonstrated that high levels of physical activity offset the inclination for obesity. Another study suggested that healthy lifestyle habits will counteract the high-risk of obesity caused by an FTO variant. Researchers in Finland proved that the risk FTO variant has no effect on the success of lifestyle interventions to reduce obesity.
Essentially, if you have the FTO variant that increases your risk of obesity, you are not destined to be obese. A healthy diet and frequent exercise have been proven to be effective as preventative measures.