It’s sad how there is still a giant controversy over negative calorie foods. The negative calorie foods diet never makes the claim that a food actually has “negative calories.” There’s no physical way that a food could contain less than zero of anything since the zero is, by definition, the lack of anything.
The idea behind the zero calorie diet, a name for the diet that is rapidly gaining popularity, is that you eat low calorie foods that because of their high fiber, digestive enzymes, and low calories, result in a caloric deficit, hence the negative calorie effect.
This deficit is what makes negative calorie foods work. The idea in producing a deficit is that your body burns more calories than the food gives you. For example, say a piece of celery has 10 calories, but your body has to burn 20 calories worth of energy to digest it. That results in a loss of -10 calories. That deficit is what makes the zero calorie diet work.
All the foods in the negative calorie foods list are either fruits or vegetables, since these are only types of foods that can create a negative caloric effect.
There is a high demand for negative calorie foods recipes, and while partial lists of negative calorie foods are pretty easy to search for and find online, figuring out how to work them into a diet with recipes and meals as opposed to just an occasional snack is much more difficult.
Negative calorie foods are meant as a supplemental diet, not an end all be all description of how to eat. The zero calorie diet uses negative calorie foods to their maximum potential to help you hit your dream weight loss goals.