Genetics and Obesity

Obesity is characterized by an excessively high amount of body fat or adipose tissue.
 It tends to run in families, suggesting that it may have a genetic cause.
 However, family members share not only genes but also diet and lifestyle habits that may contribute to obesity.
 Still, growing evidence points to heredity as a strong determining factor of obesity. Nevertheless, many people genetically predisposed to obesity do not become obese or manage to lose weight and keep it off.

 Although rare obesity syndromes caused by mutations in single genes have been described, by far the greatest proportion of obesity in humans is not due to mutations in single genes.
 Studies indicate that inherited genetic variation is an important risk factor for obesity. Evidence from twin, adoption and family studies strongly suggests that biological relatives exhibit similarities in maintenance of body weight.
 Genetic factors also are beginning to be implicated in the degree of effectiveness of diet and physical activity interventions for weight reduction.
 However, it does not mean that people with susceptible genotypes will have to live obese his whole life.

 In the longer term, understanding the genetic variations that influence energy metabolism may help us to understand the underlying biological factors that affect weight gain and energy expenditure. Also, to recognize that obesity may be due to a metabolic condition rather than a flaw in character is important both for the people who are affected and for society as a whole.
 The public health messages to prevent overweight emphasize a nutritious diet and daily physical activity. Many who follow this advice from the outset are able to maintain a healthy weight, even with a genetic susceptibility to gain weight.
 However, these lifestyle interventions have a range of effectiveness, especially if obesity is already present. For people who are already overweight, the public health interventions aimed at the general population are not a complete solution. Insights from genetics and molecular biology in controlling appetite and activity may provide more effective therapies for treatment.