THE INSTRUCTOR OF my self-defense class asked us students to each describe something we had done in our lives that we thought we couldn't do. Following on the heels of my dismayed realization that I had nothing to describe came the fervent avowal to start on a regimen of bravery and self-challenge.

After a quick rundown of personal "can't do" scenarios, I came up with one that didn't require taking time off from work or a complete personality makeover: a fast. The thought of going without food had always frightened me. What if I pass out from low blood sugar? What if I start hallucinating? Besides, how am I supposed to function if I don't have any energy coming in?

Fasting comes in varying forms and levels of intensity. It does not have to mean going without food entirely. Many people undergo fasts as an essential element of particular holy days or rituals, but with my irreligious upbringing, I'd never had a built-in reason to fast. It's worth noting that fasting is a part of many, if not most, religions.

For my first fast, which I set for three days, I opted to allow veggies and fruits in addition to my "cleansing cocktail." The cocktail is a recipe my friend Steve, who fasts regularly, let me in on, and it seems to be widely circulated in fasting lore and literature, with some variations: about eight ounces of water mixed with two tablespoons or so of grade B or C maple syrup (less refined is supposed to mean more nutrients), a squeezed-out lemon, and cayenne pepper – one-tenth of a teaspoon or to taste (it's supposed to help draw out toxins from your system). Actually, since Steve doesn't like the taste of cayenne, he just takes it in capsules, but I like the bite – kind of like Tabasco in a bloody mary. In preparation for my first fast, to ease starvation panic, I splurged on yummy organic juices and dried fruits (mango!) to keep around in case the hunger pangs became unbearable.

Like most people, I don't eat just when I'm hungry. I may also eat when I'm anxious or bored, or when food is in front of me. Like most people, I often eat because I can. The number of calories available per capita through the U.S. food supply has steadily increased over the last 30 or so years, to the point that we now have enough food to feed the population twice over (yet some Americans are starving). Our consumption of food is also increasing. There is no doubt most of us eat more than we need.

Notably, nutritionists have difficulty calculating how much the average American actually consumes, because people don't remember what they've eaten. We are lucky enough as a society to have food in such abundance and convenience that we aren't forced to remember each item that passes our lips. This ease is also true, for the average person, of breathing, or thinking, or moving limbs. These are necessary functions, and they are also pleasures; certain practices (for example, yoga, meditation, and dancing) exist to bring them to the conscious level of human awareness.

Fasting is not about not eating. It's a way of paying attention to what and how you consume and the effects on your body and mind. Fasting is also a multifaceted pleasure. For one, just the occasional change in my eating routine and having to ask myself whether I need to eat (or whether I'm eating for another reason) makes me feel more alive. When I do eat something, I really feel the result of that intake of energy. I also am pleasantly compelled to savor, because I know I won't be eating again immediately, and because my taste buds respond more intently as a result. It's sort of like weight lifting: it hurts, but you also remember that you have a particular muscle and get reacquainted with how it functions. And yes, another pleasure is daydreaming about what I'm going to eat when I have free rein again (pesto, strawberry ice cream ...), and then, eating, I almost feel like I'm tasting that flavor for the first time.

Like anything worthwhile, fasting is not one-size-fits-all. It's also controversial. Some swear by its rejuvenating and cleansing powers; others decry it as bogus in the best case and harmful in the worst. Of course, anything done to an extreme, and especially inattentively, will likely be harmful.