DIET
According to Wikipedia:Dieting is the practice of ingesting food in a regulated fashion to achieve or maintain a controlled weight. In most cases the goal is weight loss.
Diet food refers to any food or drink whose recipe has been altered in some way to make it part of a body modification diet. Although the usual intention is weight loss and change in body type, sometimes the intention is to aid in gaining weight or muscle as in bodybuilding supplements.

EXERCISE
According to Wikipedia: a physical exercise is any bodily activity that enhances or maintains physical fitness and overall health. It is often practiced to strengthen muscles and the cardiovascular system, and to hone athletic skills. Frequent and regular physical exercise boosts the immune system, and helps prevent diseases of affluence.
Exercise is good for us to keep health.And it is control weight efficient.I like physical exercise,especialy like basketball.