All foods have some calories. No food is actually a "negative calorie" food. But some foods have the effect of "negative calories". Negative calorie foods require more calories than they actually contain to digest them! Calories from these foods are much harder for the body to breakdown and process. In other words, the body has to work harder to extract calories from these foods. This gives these foods a tremendous natural fat-burning advantage.
A piece of dessert consisting of 400 calories may require only 150 calories to be digested by our body, resulting in a net gain of 250 calories which is added to our body fat! According to this theory, for example, if you eat 100 calories of a food that requires 150 calories to digest, then you've burnt an additional 50 calories simply by eating that food. Typically, a 25 calorie piece of broccoli (100 gram) requires 80 calories to digest, resulting in a net loss of 55 calories from the body fat!! Thus, the more you eat, the more you lose weight!!!