Define Genetic Susceptibility Factors for Obesity?
Some people inherit a tendency to become fat. Earlier, it was thought that genetic inheritance ranged from 66% to 80% but now it is believed that our chances of inheriting our parent's BMI is about 33%. Obesity or thinness of an individual is inherited, basically from the biological mother. If our biological mother has been overweight as an adult, the likelihood of our being heavy is about 75%. A number of genes are implicated in pathogenesis of obesity: The two genes which recently have received much attention are the ob gene and the β3 - adrenoreceptor gene. The ob gene produces leptin (a hormone) which is normally secreted from fat cells. Mutations in the ob gene cause obesity. Treatment of obese mice with leptin has shown to reduce food intake and body fat. Some scientists are of the opinion that the ob gene may not have a major role to play in human obesity. The β3 - adrenoreceptor gene is basically located in adipose tissue. It regulates Resting Metabolic Rate and oxidation of fat in human beings. A mutation in this gene may lead to weight gain. In some individuals, it may increase the body's ability to store fat when food is limited and cause an increased risk of obesity when plenty of food is available and energy expenditure is reduced. However, this does not mean that it is inevitable for a person to be obese because of genetic mutations. Expression of the genetic tendency may be controlled by appropriate life style modifications also.