Genetic Aspects of Obesity

The etiology of obesity is multifactorial. Social environmental factors, such as advertising or consumer pressure, and material environmental factors, such as means of transportation, architecture, and the constant availability of high-calorie food, have created an “obesogenic” environment that promotes obesogenic behaviors. These include consuming large, high-calorie meals, little physical activity, and/or spending a lot of time in front of the television, computer, or gaming console. However, these factors have different effects on different people; they do not lead to an increase in body weight for everyone. The predisposition for obesity is largely hereditary. This has been most impressively demonstrated by three experimental twin studies. In one study, twin pairs were deliberately given an energy intake that was too high for their body height, while in two other studies, they were given an intake that was too low. These studies consistently showed that there were groups of participants with very strong weight gains or losses, those who hardly reacted in terms of body weight, and an intermediate group with moderate weight gains or losses. The fact that weight changes were very similar within a twin pair, while there were large differences between different twin pairs, suggests a strong hereditary component.