The Root Cause of Obesity & Belly Fat: Overweight? Struggling to lose weight? Are you spending countless hours in the gym, but you do not see the results you expect. If so, the main cause of the problem is an imbalance of energy in which energy intake exceeds energy expenditure, resulting in excessive accumulation of white adipose tissue (WAT), which has nothing to do with dieting or a lack of exercise. Unfortunately, an accumulation of WAT causes obesity, which is a serious life-threatening health condition, affecting nearly 650 million people worldwide, or 13% of the global population.