A balanced diet is one that contains all the essential nutrients like carbohydrates, protein, fats, vitamins, minerals, fibre and water in optimum quantities and in appropriate proportion to meet the requirements of the body.
The body is a machine that keeps on working throughout the day. It needs energy for every activity that we perform in our daily routine. This energy comes from the food in the form of calories which is the fuel for our body. Even when we sleep the body has to keep on working; for example, we continue to breathe and the heart keeps on beating.
Physical activity is directly related to the calorie requirement. A sedentary worker would need about 1600 calories per day whereas an active person may require about 3000 calories. Foods may be put into two categories depending on whether they give us calories. Category I includes vitamins, minerals, fibre and water which contain zero calories. Category II includes carbohydrates of which 1 gram gives 4 calories; protein, 1 gram of which gives 4 calories and fat, 1 gram of which gives 9 calories.
Hence a balanced diet requires a calorie break up of 70% carbohydrate or 1120 calories; 20% protein or 320 calories and 10% fat or 160 calories.
Examples are pulses, cereals and vegetables which contain invisible fats and meet the requirements of our diet naturally, so that one can avoid visible fats like butter and oils which are unnecessary in the diet. Proteins come from animal foods like milk, meat, fish, eggs and plant foods like legumes and cereals. Carbohydrates come from rice, potatoes, sugar, wheat, fruits and glucose. Organic substances in food are called vitamins. Carotene, for example, is found in carrots which provide Vitamin A to our bodies. There are 16 chemical elements like oxygen, potassium, carbon of which our body is composed. These minerals, along with vitamins are the life substances of the body and are necessary for the healthy development of the organism. Fiber is present in barley, oats, legumes and fruit and is the indigestible but useful component of our diet. Water both natural and mineral, gives us zero calories and is essential for life.