Common Gene Variant Drives Weight Gain

Common Gene Variant Drives Weight Gain

One in two people have a gene variation that drives overeating; healthy lifestyles blunt the effects

More than one-third of American adults aged 65 and over are obese. Excessive weight promote heart disease, high blood pressure, diabetes, gallstones, breathing problems, and certain cancers.

Overweight results from a blend of diet, activity, genetics, stress, personal metabolism – how your body changes food and oxygen into energy – and more. Recent research has found that almost one in two people – 45 percent – have a variation in a gene called FTO that’s linked to a 20 percent increase in the risk for obesity.

And about 16 percent of the American population have two copies of the FTO gene, which makes them 67 percent more likely to become obese.

(Carriers of FTO gene variants also have smaller frontal lobes in the brain, less verbal fluency, and an increased risk for incident Alzheimer’s disease.) The link between the FTO gene variation and risk for obesity is strongest in Caucasians, moderate in Asians, and is not seen in African-Americans.

Exercise seems to counter the effects of the FTO variants … see “Genes are not destiny: Lifestyle can help overcome heritage”, below.

A genetic test for FTO variants is not yet commercially available. Some researchers think that if people knew they had a “bad” FTO gene variant, this would motivate them to exercise and watch their diets. But others fear that such knowledge would make carriers of the weight-promoting FTO variants feel helpless and demotivate them from efforts to follow a healthy lifestyle.

Obesity gene undermines impulse control

Recent research has convincingly linked certain variations of the FTO gene to obesity, but the reasons for that link have been unclear.

The new analysis involved 692 people participating in the Baltimore Longitudinal Study of Aging (BLSA) – including 69 people who agreed to annual PET brain scans (Chuang YF et al. 2014).

Most of the participants were upper-middle class white people and all were free of chronic diseases at the outset of the study.

BLSA researchers periodically measured the participants’ body mass index (BMI), asked about their eating patterns, and gave them cognition (thinking/memory) tests, and personality tests designed to determine their impulsiveness and self-discipline.

As in the general population, 45 percent of the percent of the people in the study had one or two copies of the FTO variant.

The results linked the presence if the FTO gene to several key trends and characteristics:

• Greater gains in BMI and weight.
• Greater tendency to favor fatty foods other calorie-dense fare.
• Reduced function in a brain region (medial prefrontal cortex) that controls impulsivity and responses to the taste and texture of food.

In other words, the new study confirmed that having the gene leads to greater weight gain over time, probably because it cripples impulse control and leaves people less able to resist fatty, calorie-dense foods.

As lead author Madhav Thambisetty, M.D., said, “There may be a common biological factor underlying both the risk for obesity during aging as well as obesity-related behavior like your ability to resist impulse eating.” (HD 2014)

If future studies confirm these results, it will mean that people with the FTO gene need to fight their inherited weakness by taking extra steps to maintain a healthy weight.

Genes are not destiny: Lifestyle can help overcome heritage

Fortunately, other research shows that having these genetic traits does not doom people to obesity. Previous studies show that people can overcome the risk of having the FTO gene through regular, vigorous, long-term exercise (Andreasen CH et al. 2008; Rampersaud E et al. 2008).

Although it is not the most accurate measure, the easiest way to find out whether you may be overweight or obese is to calculate your body mass index (BMI).

BMI is also a good gauge of your risk for diseases associated with excess body fat. You can use theonline BMI calculator at the National Heart, Lung, and Blood Institute website to determine your BMI.

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