I'm sure we have all heard about this one, but I have never actually tried it. Supposedly certain foods require more calories to digest them than you get from eating them.
Green vegetables are low in calories. You can eat a lot of them without getting fat – yet at the same time the fibrous content can ‘fill you up’. There are some green vegetables in particular that are very low in calories.
Every food requires some energy in order to digest it (called the thermic effect of food). Some green vegetables may actually have some of their calories burnt up just to digest them. This is the “negative calorie” process.
Example Green Vegetables
Proponents of the Negative Calorie Diet suggest that eating a stick of celery (5 calories) will burn up 95 calories.
My guess is that you don't want to be too far from a toilet if you go on this diet. I also have a feeling that your skin color would turn green. I know that it happens when you eat too many orange things like carrots. lol