http://www.optimalnutritions.com/perfect-biotics

[Dallas Smith]

Some foods naturally have zero calories while some are converted into zero calorie foods during digestion, so that you can call them calorie-free. The foods which require more calories to Perfect Biotics digest them than the calories they have through their nutritional content are known as negative calorie foods and thus they become calorie-free foods during the process of digestion. You can consume calorie-free foods in as much quantity as you wish, without feeling guilty! These foods can be included in all types of weight loss diets. Here is a list of foods that provide zero calories.

http://www.optimalnutritions.com/perfect-biotics