When I started yoga as a teenager, it was not offered at every health club and YWCA like it is now. In fact, it seemed very foreign. Suspect. People confused it with yogurt and both were just weird. Things have changed, and you'd be hard-pressed to find a health-conscious person who hasn't at least tried a yoga class. With the proliferation of the practice, however, some of its teachings have been diluted, particularly the enchanting yogic dietary precepts. While experts and mock experts debate ceaselessly about how we ought to feed ourselves, and diets go in and out of style more rapidly than hemlines or hairdos, yoga hasn't changed its basic dietary recommendation for over 2,000 years. It is: Choose pure foods, and enjoy them in moderate amounts.
The yogis classify foods, and everything else for that matter, in groups called gunas, the basic characteristics of creation. The three gunas are tamasic, the quality of gravity; rajasic, the quality of motion; and sattvic, the quality of light.
Tamasic foods are those considered lifeless. They include anything stale or tasteless, leftovers of more than 24 hours and anything that's been in the freezer for a long time, and also aged cheese, alcoholic beverages, deep-fried fare, and all highly processed foods with chemical additives. The teaching is that too many of these promote lethargy and fatigue and lessen our sensitivity to beauty and virtue.
Rajasic foods -- meat, eggs, refined sugar and soft drinks, stimulants like coffee, and dishes with fiery spices and lots of salt -- set our body rhythms at full speed ahead. When taken in excess, these can add to our stress levels and make us driven and high-strung.