Diets affect the "energy in" component of the energy balance by limiting or altering the distribution of foods. Techniques that affect the appetite can limit energy intake by affecting the desire to overeat.
Consumption of low-energy, fiber-rich foods, such as non-starchy vegetables, is effective in obtaining satiation (the feeling of "fullness"). Exercise is also useful in controlling appetite. (Extreme physical fatigue, such as experienced by soldiers and mountain climbers, can make eating a difficult chore.)
The use of drugs to control appetite is (potentially) dangerous. Stimulants are often taken as a means to ignore (normal, healthy) hunger by people who are not actually overweight. Even those who are overweight to the point that it will impact their long-term health are unlikely to benefit from complete fasting or radical changes.
There are several kinds of diets:
Weight-loss diets restrict the intake of specific foods,
or food in general, to reduce body weight. What works to
reduce body weight for one person will not necessarily work
for another, due to metabolic differences and lifestyle
factors. Also, it's important to note that short-term dieting
does not necessarily lead to weight loss in the long term.
Reducing the body's food supply causes it to stockpile excess
fat as a starvation response once normal eating is resumed
- meaning crash dieting leads to small short-term weight
loss, then an increase in weight shortly afterwards.
Many professional athletes impose weight-gain diets on themselves.
For example, wrestlers may overeat in order to achieve a
higher weight class. American football players may try to
"bulk up" through weight-gain diets in order to
gain an advantage on the field with a higher mass.
