By Mark Faries, PhD

Howdy, I am Dr. Mark Faries and we are here to separate lifestyle medicine fact from fiction.

Some recent media attention has highlighted scientific discoveries that might suggest that a person is genetically predisposed to being fat or lazy. So is this claim that our fat and lazy genes are to blame for our health issues a fact or fiction?

A colleague of mine recently published a scientific paper about a study using rats suggesting that genetics and gene products can contribute to laziness.

This report got quite a bit of media attention, which led to message board posts such as, “now I can blame my genes for not wanting to get off of the couch” or “leave it to scientists to find another reason for people to be lazy.”

Simply stated, geneticists use very intricate calculations to suggest that most traits, body weight or exercise motivation, for example, are about 50% heritable. However, environmental enrichment—such as a consistently healthful diet and routine physical activity—can more than make up for poor genetics.

So, in the same study published by my colleague Dr. Michael Roberts, the lazy genes do likely exist, but the body fat gain in these lazy rats was prevented when they were given access to running wheels over a 6-day period. Minimal voluntary running—due to laziness—was still able to completely prevent gains in body fat.

When applied to humans, these findings suggest that even a little bit of exercise can cause drastic body composition changes.

Likewise, muscle samples taken from the lazy rates that ran very little daily distances, revealed increases in markers suggesting positive training adaptations.

Thus, while some people might be more genetically predisposed to be lazy, a little bit of daily physical activity can go a long way in improving various physiological variables that affect our health.

Humans possessing certain genetic variations of the famous “fat mass and obesity gene” or FTO gene have an increased risk of being overweight or obese.

However, recent data suggest that the obesity related FTO gene is not associated with obese body types for people who maintain routine physical activity levels. In other words, this is yet another example whereby exercise can do more than make up for poor genetics.

Environmental pressures, such as watching TV, over-eating and desk jobs, affect the chances that we will gain body fat due to our genes. In fact, recent research data suggest that over 70% of Americans are overweight or obese.

So, are fat and lazy genes to blame for most of us being overweight and lazy?

Well, geneticists will tell you that the genes are one side of the coin regarding any tendencies for weight gain and laziness. However, there is ample evidence that suggests that living a consistently healthy lifestyle can override poor genetics.

That means the claim that our fat and lazy genes are to blame for our health problems… is mostly false.

Phenotypic and molecular differences between rats selectively bred to voluntarily run high vs. low nightly distances. Roberts MD, Brown JD, Company JM, et al. (2013). Am J Physiol Regul Integr Comp Physiol. 2013 Jun 1;304(11):R1024-35. doi: 10.1152/ajpregu.00581.2012. Epub 2013 Apr 3.

Physical activity and the association of common FTO gene variants with body mass index and obesity. Rampersaud E, Mitchell BD, Pollin TI, Fu M, Shen H, O’Connell JR, Ducharme JL, Hines S, Sack P, Naglieri R, Shuldiner AR, Snitker S. (2008). Arch Intern Med. 2008 Sep 8;168(16):1791-7. doi: 10.1001/archinte.168.16.1791. Erratum in: Arch Intern Med. 2009 Mar 9;169(5):453.

Physical activity attenuates the influence of FTO variants on obesity risk: a meta-analysis of 218,166 adults and 19,268 children. Kilpeläinen TO, Qi L, Brage S, Sharp SJ, Sonestedt E, Demerath E. et al. (2011). PLoS Med. 2011 Nov 8(11):e1001116. doi: 10.1371/journal.pmed.1001116. Epub 2011 Nov 1.

Physical activity in the United States measured by accelerometer. Troiano RP, Berrigan D, Dodd KW, Mâsse LC, Tilert T, McDowell M. Med Sci Sports Exerc. 2008 Jan;40(1):181-8.

Mark D. Faries, PhD

Mark has a PhD in Behavioral Health and an MS in Exercise Physiology. He is an Associate Professor and State Extension Health Specialist with Texas A&M AgriLife Extension and has developed lifestyle medicine curriculum and advocacy. He has served on the Board of Directors of the American College of Lifestyle Medicine, is founder of Lone Star Lifestyle Medicine for Texas and is founder of

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