Since diet products need to have less than 5 calories to be labeled calorie free, do most diet sodas tend to have just under five, or do they have have zero to one calorie per serving? does coke zero really have zero calories per serving?
According to the Food & Drug Administration, a food product can be labeled as calorie-free or zero-calorie if it has 5 or fewer calories per serving.
Issue 4 of the Small Bites newsletter focused on fats, and had a similar explanation for the labeling of trans fats.
A bag of chips can claim to be trans-fat free as long as long as it contains less than 1 gram per serving. If a bag has 0.8 grams per serving and you have three servings, you've just had almost 2.5 grams of trans fats (mind you, you should ideally be getting zero grams a day and the maximum recommendation is set at just 2 grams)!
A standard can of diet soda provides approximately 2 calories. Not exactly zero calories, but also not worth worrying about.
The main concerns with diet soda are the phosphoric acid (which lowers calcium levels), the artificial sweeteners (which, being hundreds of times sweeter than real sugar often leave people craving more sugar) and the fact that it often replaces more healthful beverage choices (i.e: water, low-fat milk, etc.)