According to ayurveda, the body is programmed to direct its energy toward cleansing and assimilation in the hours just before midnight, when agni (digestive fire) is weakest. To support this process, ayurvedic physicians recommend refraining from late-night snacks and going to bed around 10 p.m. By fasting for 12 hours every night—between dinner and breakfast (7 p.m. to 7 a.m., for example)—you free your body from the burdens of meal-related digestion so it can conduct mental, emotional, and cellular cleansing in a more concentrated way.

The 12-hour fast also respects agni’s daily waxing and waning cycle which, according to ayurveda, corresponds to the rising and setting of the sun. That’s why it is wise to eat a healthy breakfast in the morning, eat your largest meal at noon when the sun is the strongest, eat a lighter dinner as the sun is waning, and then allow your stomach to rest until the sun comes up the following day. This fast supports metabolism, prevents accumulation of ama, normalizes weight, and combats kapha imbalances (which are particularly common in the spring).