How Much Weight Will You Lose While Fasting?

How many calories do you usually burn in a day? According to CalorieKing, I need about 2400. A pound of butter is 3200 calories. So I should burn about three cubes of butter's worth of calories a day. Not coincidentally, that is about how much weight I lose per day when I'm fasting: roughly 3/4ths of a pound.

Since the caloric content of butter is probably the same as the fat on my body (or close enough), this all makes sense and it's easy to think about.

By the way, it will seem like you're losing more weight than that, at least for the first day or so, because food, and especially carbohydrates, cause your body to retain a certain amount of water. So you may immediately lose two or three pounds. But when you start eating again, that water weight will come back.