Yogis are known to be fasters. Some fast because they practice Hinduism or subscribe to religious beliefs. Others fast to exercise self-control. Whatever the reason, it's important to be knowledgeable of potential health benefits and health risks associated with this practice.
Fasting is abstinence from food, or food and drink. Physiologically, your body enters a "fasting" state 4-8 hours from your last meal. Deliberate fasts most commonly last 1-5 days. Many people fast to rest the digestive system, the belief being that humans eat frequently, several times a day, overworking the digestive system. The notion is that fasting will restore the digestive system, helping to detox the body. There seems to be some truth to this, although I could not find any solid, scientific evidence. Your digestive system will begin to rid itself of free radicals once the fast begins. The only downside is that stomach acid will also decrease, so it's important not to jump back into eating heavily once your fast is over. This shouldn't be too much of an issue, because your stomach will have decreased in size, so eating smaller meals will satisfy your appetite like larger meals used to.
Juice fasts seem to be the most popular way to fast these days. Subscribers declare that their appetite isn't distracting and their energy is restored after a three day juice fast. Fruits and veggies are high in crucial vitamins and minerals, so this is a way to receive your daily recommended vitamins and minerals without consuming solid food. Like any fast, juice fasts can leave you dizzy and lightheaded. A sharp drop in blood sugar may result, leaving you weak, nauseous, and moody. Before you start a fast, it's important to remember that you will likely experience at least one of these side effects, and to plan accordingly. When I have fasted in the past, I got really, really moody. I didn't suffer from too much hunger but wasn't able to socialize normally.
It's also important to consider potential weight loss and metabolism. Will fasting cause you to lose weight? Absolutely. You can lose around a pound a day, in my personal experience. This will happen to pretty much anyone. A more controversial question would be: does fasting help or hurt my metabolism? We have heard for years that small, frequent meals is more beneficial to the metabolism, causing your metabolism to rise and stay high throughout the day. This is true, and as such, leads many critics of fasting to believe that if you fast, your body goes into "starvation state", dropping the metabolic rate in order to preserve calories. This is both true and false. When I refer to "metabolic rate", I am referring to "basal metabolic rate", which is the more permanent rate in which you metabolise food at rest, not the initial increase in metabolism which occurs up to 3 hours after eating (eating calories burns calories). In short term fasts, for up to 60 hours, basal metabolic rate can actually decrease as a result of fasting which will leave you more energetic and enable weight loss. After 60 hours, your body does enter a "starvation mode", and your basal metabolic rate increases significantly. Therefore, fasting is safe on the metabolism for about two and a half days.
To fast or not to fast? That is the question. After researching this topic, I was actually surprised at how safe fasting is. However, the side effects can be debilitating, so it's important to bring the yogic lesson of "listen to your body" with you throughout the fast. If your body starts shutting down, if you find yourself practically passing out, for the love of all things please eat something. This is not a sign of defeat but rather common sense.