Both sides of the back waist flab formation reasons are: first, less exercise, usually less exercise in life, may appear on both sides of the back waist flab formation; second, diet eat rice, noodles, potatoes and other staples, as well as oil, meat, chocolate and other food more, and eat less vegetables, resulting in the formation of both sides of the back waist flab; third, dressing habits, if usually prefer to wear loose clothing, may lead to meat sagging, appear back waist flab formation; fourth, there may be because of genes, primary obesity.