Your diet is the type and range of food that you regularly eat.

If a doctor puts someone on a diet, he or she makes them eat a special type or range of foods in order to improve their health.

If you are on a diet, you eat special kinds of food or you eat less food than usual because you are trying to lose weight.

If you are dieting, you eat special kinds of food or you eat less food than usual because you are trying to lose weight.

Diet drinks or foods have been specially produced so that they do not contain many calories.

If you are fed on a diet of something, especially something unpleasant or of poor quality, you receive or experience a very large amount of it.