Avoid any food or drink that will cause a spike in insulin because insulin is the hormone that regulates whether you store fat or release it. By maintaining low levels of insulin throughout your fast, you ensure that the body has a chance to release — and use — fat stores, rather than continuing to pack fat around the typical trouble areas of your tummy, hips, thighs, butt, and arms.
Overall, what you can consume and what you can't consume during your intermittent fasting period is pretty simple. If you have to question whether or not you can eat or drink a particular food or beverage while on your fast, chances are you should probably just say “no thanks.”
After all, you're only passing on that item once or twice a week. What you can't eat or drink during your fast includes the following:
Anything with hidden calories
Be careful of what you put into your mouth during a fast; sometimes calories are hidden in places you don't expect. The difference between making and breaking your fast can come down to the cream and sugar you put into your coffee.
Black coffee, black tea, and other approved beverages during your fasting period have minimal calories (2 calories or less) and therefore are allowed. Adding sugar or creamer to these beverages constitutes unnecessary calories and therefore isn't allowed during the fast.
Chewing gum, including sugar-free gum
The idea behind chewing gum isn't bad. In fact, evidence suggests that humans have been chewing on the leaves or sap of the gum tree for hundreds of thousands of years. However, you should avoid chewing gum, both regular gum and sugar-free.
Regular gum has sugar (and also calories). Regular chewing gum is typically sweetened with corn syrup, which is a form of sugar called glucose. This sugar gives you a rise in blood sugar each time you pop a piece.
Sugar-free chewing gum also makes the list as a fasting no-no because of the artificial sweeteners. Furthermore, a small percentage of the population has a genetic intolerance to phenylalanine, which exists in aspartame, that limits how much phenylalanine they consume. When it comes down to it, you need to ask yourself if the artificially sweetened gum is worth it — or can you get the same benefits by choosing a healthier alternative.
Diet beverages
No matter whether it's diet soda, diet iced tea, or some other kind of diet drink, you want to steer clear of it during your intermittent fast. Although diet drinks (and sugar-free gum) typically don't have more than a few calories, they are restricted to avoid the potentially harmful chemicals that can be found within them and their potentially negative effects on your health.
Furthermore, a recent study from Purdue University suggests that diet soda can actually increase insulin levels — another reason to keep clear of the stuff.
Although one of the many great benefits of fasting is weight loss, a goal that noncaloric sweeteners help many people achieve, fasting is also a time to give your body a break from the chemicals inherent in so many of the drinks (and foods) that you enjoy on a regular basis.
On your fast days, take a break from the fake stuff and stick to water, black coffee, unsweetened tea, and other noncaloric and healthful beverages.