What Causes Obesity?
Many people think obesity is simply a result of overeating. Although this is true for people with certain eating disorders or glandular abnormalities, it's not that simple. Ongoing research shows that obesity is a complex combination of hereditary (genetic) and environmental factors that, once established, is almost impossible to control by dieting. The disease is also considered chronic and worsens with time, which means that it requires lifelong control and treatment.
Unfortunately, medical weight loss programs – diet, exercise, drugs, and behavior modification – fail in at least 95% of morbidly obese patients no matter how much they want to lose weight or how hard they try. And even patients who are 50-100 pounds overweight may be unable to shed pounds and improve their health without some form of medical intervention.
Hereditary and environmental factors also play a role in obesity. Some people, like the Pima Indians of Arizona, have an inherited trait that makes the body very efficient at storing fat. The same is true of their genetic counterparts, the Pima Indians who live in the Sierra Madre region of Mexico. Interestingly, the Arizona Pima – studied by the National Institutes of Health since the 1960's – have an extremely high incidence of morbid obesity and diabetes and the Mexican Pima do not, even though both groups consume a similar number of calories each day.
Environment and behavior appear to account for the dramatic difference between the two groups. The Mexican Pima average up to 40 hours of physical labor each week and eat the traditional Pima diet, which is very low in fat. In contrast, the Arizona Pima average only about 2 hours of physical labor per week and eat a diet that consists of about 40% fat.
Clearly, lifestyle can foster obesity in people whose body stores fat efficiently. In the United States, the convenience fast food, large portions, little or no structure in meal planning, high-fat, high-calorie snacks and sugar-laden sodas, and a lack of proper exercise magnify the hereditary factors that underlie obesity.