It makes sense: if you don't eat, you'll lose weight.
But recent research has given rise to the idea of mini fasts as a way to control blood sugar, weight, and even help you live longer.
One study from England found women who followed a five-two diet, where they ate normally for five days a week, and ate 500 calories of lean protein the two other days, lost significantly more weight than women who tried to eat fewer calories all week.
These mini fasts can help lower your insulin levels, which can lead to lower levels of fat storage, but without affecting muscle mass.
Part of the success of these mini fasts is that people find them easier to follow.
And apart from the physical effects, many who have been on the diets report feeling more energized and focused.