12 Sep 2007
Regardless of popular theories behind behavior and metabolism, people in the reason world gain and lose body-fat. How does this happen? It occurs due to an unbalanced energy budget. That is, by eating (consuming) either more or less food energy than they spend. There is an energy balance when the caloric intake equals the caloric expenditure.
The primary cause of excessive body-fat and obesity is an energy imbalance in the body.
Let's examine a positive energy balance. A positive energy balance occurs when the input of calories (food) exceeds the expenditure, (you eat more than you spend). For example 3,500 calories of excess food consumed-- that the body does not burn for energy-- one pound of fat is stored in the body.
Improper diet, overeating, hormone disturbances, physical inactivity and even extensive dieting may create a positive energy balance which leads to weight gain.