Abstract

We eat food for survival, to get enough energy to work and maintain good health. This is possible through a variety of chemical substances in food, such as nutrients, non-nutritional compounds and also certain helpful microorganisms. These food constituents assist in producing energy from food and play specific roles in normal body functioning, growth and development. We spend energy in carrying out internal body functions such as digestion, and in doing physical activities. The concept of energy balance to maintain desirable body weight is explained in this chapter. Amongst nutrients, carbohydrates, proteins, and fats are macronutrients, that we require in large amounts. Raw and cooked foods rich in macronutrients are described with examples. Types of carbohydrates, proteins, composition of dietary fats and oils, essential fatty acids and cholesterol levels in foods are also illustrated. Food also contains micronutrients –vitamins and minerals, that the body needs in small amounts. Micronutrients are essential for many body functions. We need to obtain both the macro and micronutrients daily from the diet in desired quantities, known as Recommended Dietary Allowance (RDA). The interrelationship of macro and micronutrients in metabolic functions is elucidated in this chapter. Similarly, the fundamental knowledge about basic food groups and nutritive values of foods, the bioavailability of macronutrients and their role in biological functions are explained. A brief outline of the potential role of protein, fat and carbohydrate intake in obesity, metabolic disorders and health is also provided.