Yogis use food to detox and unblock their systems before starting meditation. The rest of us can borrow from their diet ideas to feel light and bright too.

"Most people dig their graves with their own teeth," writes Yogacharya Omkar Nath.

In Delhi you can hardly leave home without being assailed by food. Unfortunately, street food is all rajasik and tamasik. "Rakshasik," says yoga instructor Ashutosh Thakur, with a shudder: "Where there is swaad, there is no swasthya."

The body is composed of five elements: earth, water, sunlight or fire, air and ether or space. Food, too, is a combination of these elements and, taken in the right manner, is the best way of keeping a person healthy and energetic.

Your body should tell you when to eat, rather than the clock or your palate. Eating in a relaxed way -- around a table with your family -- is best. Watching a horror movie on HBO as you eat your dinner is a bad idea.

Eat satvik foods. Foods that increase age, intellect, strength, health, happiness and affection, those which are by nature pleasing to the mind are all satvik, according to the Bhagavad Gita.

Meat of any kind is strictly forbidden because it is acidic in nature. The body needs a balance of acid (20 per cent) and alkali (80 per cent), for which it needs the best combination of protein, carbohydrate, fat, vitamins, natural salts and roughage.

Sprouts attract almost fanatical devotion from yoga practitioners. Since they are alkaline they help balance an acidic diet, and they contain every food group.

"Eat the liquids and drink the solids," says Omkar Nath. He means: chew solids into a paste, and hold liquids in the mouth for a moment before swallowing. If you chew and swallow too quickly, the work of the teeth and saliva remains incomplete. As a result, the stomach and intestine have to work harder. Besides, you might miss some of the flavour.

"After you eat, the stomach should be filled half with food, one-fourth with water and the rest with air," says Ashutosh Thakur.

Overeating results in food putrefying in the gut, and strains the intestinal muscles. If you eat simply, you'll be less likely to overeat.

In yoga, diet is just the starting point. Yogis do not progress to meditation without having first rid their bodies of toxins. This is the real purpose of the whole physical aspect of yoga.