Negative Calorie Foods - Three Characteristics of All Negative Calorie Food

There has been a lot of back and forth in online communities on whether negative calorie foods exist, or if it's all a bunch of hooey. One thing I've noticed while doing extensive research is that often times the people who are most adamant that "negative calorie foods" is a stupid concept seem to miss what the actual negative foods concept is about. Negative calories foods are not foods that don't have calories.