Obesity and Genetics: Nature and Nurture

obesity and genetics

July 23, 2018
By Jeffrey Sicat, MD, FACE, FOMA

Defining Obesity’s Interplay among Environment, Behavior, and Genetics

Obesity is a disease that occurs when a person’s body accumulates and stores excessive amounts of body fat. The modernization of our society has contributed to higher rates of obesity through an environment that promotes increased calorie intake and decreased physical activity.

However, recent studies suggest that genetics contribute to 40-70% of obesity with the discovery of more than 50 genes that are strongly associated with obesity. While changes in the environment have significantly increased obesity rates over the last 20 years, the presence or absence of genetic factors protect us from or predispose us to obesity.

Severe Obesity and Genetics

Rare single-gene defects cause severe obesity beginning in early childhood and are associated with extremely high levels of hunger. Individuals who developed severe obesity before the age of 2 should consider talking to an obesity medicine specialist about being screened for:

  • Leptin Deficiency
  • POMC Deficiency
  • MC4R Deficiency

Obesity Genetics: A Predisposition

More commonly, people who have obesity have multiple genes that predispose them to gain excess weight. One such gene is the fat mass and obesity-associated gene (FTO), which is found in up to 43% of the population. In the presence of readily accessible food, those with the fat mass and obesity-associated gene may have challenges limiting their caloric intake. The presence of this gene and other genes can cause:

  • Increased hunger levels
  • Increased caloric intake
  • Reduced satiety
  • Reduced control over eating
  • Increased tendency to be sedentary
  • Increased tendency to store body fat

Are Your Genes Your Destiny?

While testing for genetic defects in children for early childhood obesity may be considered, testing for genetic forms of obesity in adults is of limited value. Testing for the FTO gene and other genes can be performed practically, but it is not very helpful because the treatment interventions are the same for individuals with and without the FTO gene. Knowing your family history can help you understand your risk for obesity and obesity-related conditions like diabetes and heart disease.

If you have genes that predispose you to obesity, are you predestined to develop obesity? No! While these genes can increase appetite and reduce metabolism, following a consistent treatment plan that incorporates effective nutritional, physical activity, and behavioral approaches can help prevent and treat obesity.

If weight continues to be a struggle, consider seeing an obesity medicine specialist to help develop a comprehensive medical obesity treatment plan.