99% of the time, food is a dancer's best friend. Whether or not this is true of you, it is important that you get the proper nutrition.
Nutrition refers to more than just how much you eat (surprise!) - rather, it refers to the balance of minerals, vitamins, and other important nutrients found in what you eat. To be healthy, one must partake of the proverbial four food groups, and makes sure that one's diet includes the fifty essential nutrients and replenishes lost body fluid.
If you prescribe to the general principal that you neeeed to be thinner, be warned; consuming too few calories, or too few of the important required nutrients will not help you lose weight! Instead, it may lead to illness, listlessness, and a typically low energy level (Hammond, 141). Needless to say, ability to dance well would be impaired by crash dieting.
For this reason, it is better to have a habitual way of eating. Since nutritional needs are relative to one's gender, height, metabolic rate, bone structure, and age, fad diets or dietary tricks ( the 'cabbage' diet, for example) are also not encouraged (Hammond, 141).
If a dancer needs any type of diet gimmick, that gimmick should be to eat 'energy' foods. You know the story -- eat an apple, not a candy bar when you're hungry, carbohydrates good, carbohydrate loading bad. In general, foods which confer a high amount of energy while being low in fat are whole grains, fruits, vegetables, low fat dairy products, and seeds or nuts. (Spinach flavored yogurt on melba toast - Yum!) Once again, even foods such as fruits and vegetables should be eaten in moderation, and a healthy diet includes more than just legumes or yogurt or rice cakes.