Role of Diet on performance: The energy quality of sports diet depends on correct proportion of carbohydrates, proteins, fats, vitamins. salt and minerals which are the main nutrients of the diet. 

(a) Proteins: Proteins are the main building foods and form the main constituents of muscles, tissues and blood. They supply the building material for the body during the growth process and also repair the wear and tear of muscles, ligaments and tendons. Hence, they are must essential for an athlete. The ideal sports diet should have both animal and vegetable protein in adequate quantities. 

(b) Carbohydrates: They form the main bulk of a sportsman's diet and are the main sources of energy for physical activities. These are the sources of  'instant energy' for athletic activities. This is the reason why athletes are advised to take glucose during physical activities. Glucose should be taken in specific dilution in water by those who are physically active. Atleast 50% to 60% of calories should come in the form of carbohydrates. 

(c) Fats: Fats are considered a major source of fuel for light to moderate level of activity. There is different proposition of fat requirement for maximum performance, For example there is normal fat requirement for distance runner. high jumper and a gymnast because if they add weight it will hinder their performance. 

(d) Minerals: Excessive sweating during exercise, especially in hot climate, causes loss of optimum amount of sodium and potassium from the body. Hence, fruit Juices should be added to the fluids taken during and after exercise. Iron requirement of Indian athletes is comparatively higher due to increased sweating. chances of worm infestation. etc. 

(e) Vitamins: During sports activities. the need for various vitamins, particularly vitamin A, vitamin B complex and vitamin C increases. In sports vitamins are often used against one's better judgement in the hope of improving performance. Drink small volume of water frequently rather than large volumes infrequently e.g.,6-8 ounces every 15 minutes. Water makes 70% of our body weight. Sports persons should drink enough water to replace the water they lose through sweating.