If something has zero calories, it must be ok to consume during your fasting window, right? Unfortunately for you diet soda lovers, that’s false! Calories aren’t the only fast-breaking culprits—other ingredients in these fizzy beverages can derail your fasting goals.

Most diet sodas contain artificial sweeteners (e.g., aspartame, sucralose, saccharin and Ace-K), which have mixed reviews when it comes to weight loss. We know that a large percentage of Zero users fast with a goal of weight loss, so step away from the diet soda! Artificial sweeteners can contribute to weight gain, or at the very least, make weight loss harder. And who needs extra challenges on the fast track?!

Your gut also wants you to stop the pop. There was a time when researchers thought artificial sweeteners could pass through your gut without any absorption. However, a few studies have now shown that in adults and children, some artificial sweeteners actually do get absorbed. The studies demonstrate gut absorption with blood tests measuring levels of sucralose pre and post beverage consumption. It’s now argued that artificial sweeteners do interact with our gut microbiome and can alter the function of our microbiota. A big no-no if you’re fasting for true gut rest.

Artificial sweeteners don’t contain protein that would stimulate mTOR (stimulation of mTOR inhibits autophagy), however, research is limited on the actual impact of diet soda drinking on longevity. Because of the possible metabolic and gut health concerns other studies have cited, you can play it safe and assume artificial sweeteners have more of a negative impact on long-term health than a positive impact. Best to stick to your body’s fave beverage during a fast: good old H2O.

In Summary:

Fasting for metabolic health: diet soda does break your fast

Fasting for gut rest: diet soda does break your fast

Fasting for longevity: more research is needed here, but it’s safer to avoid while fasting

Comment on our latest post and tell us what you’re sipping on during your fasting and feeding windows.