Obesity: Generally, fat people think that their overweight is due to their constitution and for heredity. It could be true in some cases. But have you ever come across a fat labourer,  coolie, athlete, or mountaineer? Although, they eat a lot more than obese people,  they do not gain-weight. Why? Because they use up the calories  in physical activities. When the intake of calories is more than what is needed, the excess is deposited in the form of  fat on the body and the person gradually becomes over-weight.  Right weight and active habits are good for health.