Although many people don't realize it, diet is an integral part of yoga. Much of the yogic prescription for food comes straight from the yamas and niyimas, yoga's "do's and don'ts" as articulated in Patanjali's Yoga Sutra.
It is well established in Western science that a poor diet can contribute to the development of a wide variety of diseases, including Type II diabetes, high blood pressure, heart attacks, and some cancers. Modifying the diet can, in turn, improve health, reduce the need for medications, and in some cases reverse all signs of disease. In addition, yoga would suggest that a good diet can improve your mood, energy level, and overall well-being, and even help make the world a better place.
Ahimsa and Diet
The first yama, and the foundation of all of yoga practice, is ahimsa, nonharming. You don't want to be eating food that harms you or others. Out of concern for the welfare of animals, many—though not all—yogis choose to be vegetarians. The health benefits of vegetarianism have been demonstrated in numerous scientific studies. Vegetarians are less likely to develop all the health conditions mentioned above, and they tend to weigh less than carnivores. If your students choose to eat meat or dairy products, try to get them to bring awareness to how the animals are treated. The laws of karma would suggest that factory farming, which is both inhumane and environmentally irresponsible, is good neither for animals nor for the people who eat them.
For similar reasons, yoga would suggest that we choose organic food whenever possible. Organic food tends to taste better and to be higher in vitamin content. And while scientists can debate how harmful pesticides, herbicides, and fungicides are to human health, yoga's holistic perspective would suggest that anything strong enough to kill pests, weeds, and fungi is undoubtedly not going to be healthy for us. While testing is lacking for many chemicals—and virtually nothing is known about the cumulative effects of the stew of chemicals that all of us are exposed to—recent evidence links pesticide exposure to both male infertility and Parkinson's disease. Beyond this, we know that these chemicals harm the health of farm workers, damage ecosystems, and contaminate local groundwater. So, again, a karmic perspective would suggest that we avoid these chemicals and the agricultural businesses that support their rampant use.
Yoga and Ayurveda on Food
Yoga and Ayurveda categorize everything in the universe as being made up of three different properties, or gunas: rajas, tamas, and sattva. Rajas is the property of motion, and rajasic foods tend to be stimulating, even agitating. Onions, garlic, red pepper, and coffee are a few examples. Tamas is the property of inertia. Tamasic foods tend to be heavy, stale or low in nutritional value, and can induce lethargy. From a yogic perspective, they lack prana, or vital energy. Fast food, junk food, and something that's been sitting in the fridge for a week are all considered tamasic. Sattva is balance, and sattvic foods are fresh, pure, and high in vitamins. Think of fresh fruit or a plate of steamed, organic greens.
Diet is the centerpiece of yoga's sister science, Ayurveda. India's traditional system of medicine characterizes foods based on their taste and makes dietary recommendations based on how foods with different tastes affect people of different constitutions. For example, people with fiery pitta constitutions might be advised to refrain from overly spicy foods in favor of foods with bitter, astringent, and sweet tastes. Hyperactive vatas, Ayurveda suggests, benefit from eating warm, nutritious meals on a regular schedule, emphasizing sweet, salty, and sour tastes. Kaphas, with their tendency toward inertia, may be told to cut back on sweets and high-fat foods, opting instead for spicy, bitter, or astringent foods. Ayurveda's analysis of diet is intricate and subtle, and I suggest that anyone who is interested read more on this subject or consult an Ayurvedic practitioner.
Using Yogic Awareness to Guide Food Choices
Finding the right foods is in part a matter of trial and error. Yoga encourages people to develop their internal awareness (a regular yoga practice is a great way to do this) and study themselves to figure out which foods work best for them. A particular food might taste good, for example, but if you feel lethargic afterward, you can't sleep well, or your meditation is more distracted than usual, it may be that this food isn't agreeing with you. Encouraging your students to keep a food diary, in which they write down what they eat and how they feel later, is a great way for them to study themselves. Self-study, or svadhyaya, is, of course, one of the niyamas, or yogic observances.
If you suspect that a student's health or well-being is being adversely affected by a particular food or group of foods, a yogic approach would be to eliminate the food or foods from the diet for a week or two and see if that makes any difference. Then reintroduce the suspect food (one at a time if it's more than one food), and again ask the student to tune into how they feel. If symptoms lessen or disappear only to recur on reintroduction of a food item, that's strong evidence that it may be problematic. When your students make this kind of discovery for themselves, they may be much more motivated to avoid the problematic foods than if the advice comes from someone else, such as a doctor.
Taking It Home
The essence of the spiritual path is the willingness to undergo short-term discomfort in order to advance longer-term objectives, both personal and societal. You go to your yoga mat even on a day when you'd rather lie on the couch, or you give up a Saturday afternoon to volunteer at a local food bank. This is tapas, another niyama. Dietary tapas is the willingness to sacrifice short-term pleasure, for example, saying no to something tasty that you know is not good for you.
None of this is to say that you shouldn't eat with pleasure. Food is one of life's joys, and yoga teaches that it, like you, is a manifestation of the divine. If your students have a pattern of sullying their temples of the divine with food that is less than divine—especially food that in fact may be undermining their health—try to get them to analyze why they eat this way. Encourage them to enjoy their food but to eat slowly, mindfully, in moderation, and with gratitude. The more awareness they bring to the process, the better dietary choices they are likely to make, and the better it will be for them—and for the rest of us.
Dr. Timothy McCall is a board-certified internist, Yoga Journal's Medical Editor, and the author of the forthcoming book Yoga as Medicine: The Yogic Prescription for Health and Healing (Bantam Dell, summer 2007). He can be found on the Web at www.DrMcCall.com.