DNAWhy Weight Management

Science has made great advances in understanding causes of obesity including identifying environmental causes as well as genes that may be implicated. Major scientific effort is now directed toward assessing the interactions of genes and environment in the current obesity epidemic. Obesity results when body fat accumulates over time as a result of a chronic energy imbalance (calories consumed exceed calories expended). Obesity is a major health hazard worldwide and is associated with several relatively common diseases such as diabetes, hypertension, heart disease, and some cancers.

In recent decades, obesity has reached epidemic proportions in populations whose environments offer an abundance of calorie-rich foods and fewer opportunities for physical activity. Although changes in the genetic makeup of populations occur too slowly to be responsible for this rapid rise in obesity, genes do play a role in the development of obesity. It is thought that genes regulate how our bodies capture, store, and release energy from food including the drive to overeat (poor regulation of appetite and satiety); the tendency to be sedentary (physically inactive); a diminished ability to use dietary fats as fuel; and an enlarged, easily stimulated capacity to store body fat.

Not all people living in industrialized countries with an abundance of food and reduced physical activity are or will become obese; nor will all obese people have the same body fat distribution or suffer the same health issues. This diversity occurs among groups of the same racial or ethnic background and even within families living in the same environment. The variation in how people respond to the same environmental conditions is an additional indication that genes play a role in the development of obesity. This is consistent with the theory that obesity results from genetic variation interacting with shifting environmental conditions.