What causes obesity in america?

Obesity as per WHO is defined as the excessive collection of fat in the body to the extent that the health is impaired. Once a nutritional disorder, it has now reached an endemic. The problem is more predominant in developed country like America. The fundamental cause of obesity is an energy imbalance between calories consumed on one hand and calories spend on the other. Global increase in overweight and obesity are attributed to a number of factors like: genetic factor accounts for 25 to 30 %; Personality: type A personality is more prone to get obese than type B; Eating habits: Americans diet is rich in animal fats, relies more on processed foods etc.; Cultural environment; Lifestyle; Thermionic effects of feeding; Basal metabolic rate (BMR); Hormonal :Incidence of hormonal disorders have increased which lead to changes in body’s metabolic rate. For example hypothyroidism; Side effects of drugs etc.
There exists some amount of racial predisposition to obesity but, changing lifestyle, diet patterns and reduce physical activity are major factors responsible for obesity in America.