The number of fat cells in the body stays the same throughout adult life, and is determined during childhood. Losing or gaining weight does not affect the number of fat cells in the body. In an adult, fat cells can increase or decrease in size, but the amount of fat cells is constant, as was recently published in scientific magazine, Nature. Even when fat cells decrease in size due to weight loss, they can later receive new signals that will cause them to increase in size again. Despite all this, the combination of a controlled diet and regular exercise can make weight maintenance possible.