Question: Are there spiritual benefits for consuming only one meal a day (or one less meal a day), compared with having three meals and snacks whenever wished?
Answer: Having one near-noon meal a day is one of the Eight Precepts. (Some Buddhists take breakfast too.) This helps to train in curbing thinking about and craving for food, which is one of the Five Desires (for wealth, sex, fame, food and sleep – all under the first poison of greed), that bind us strongly to rebirth. When the Five Desires are weakened, it is easier to be liberated from rebirth. Lessening eating also trains us to focus limited energy garnered for more meaningful Dharma learning and practice.
Question: If there is a non-Buddhist who habitually has one meal a day, will this person also benefit spiritually unknowingly?
Answer: This would depend on the motivation of doing this. For example, if it is simply due to poverty or miserliness that there is less eaten, while craving for food all the time, there is no spiritual benefit. If the motivation is that in the first answer, to train for spiritual purification, there will be the benefits accordingly. However, if fasting is not done with a clear direction towards further learning and practice, it might not lead to liberation from rebirth, as liberation requires eradication of all three poisons of greed, hatred and delusion.
Eight Precepts Ceremony’s Text