Does popping your morning multivitamin end your overnight fast? What about your favorite mug of coffee or a squeeze of lemon in your water?

If fasting is already in your wellness wheelhouse or if you’re curious about adopting a fasting practice, such questions have probably crossed your mind. From sneaky sources of hidden calories to the insulin impact of certain beverages, you may be inadvertently compromising your fasting efforts.

By definition, any intake of calories, no matter how small, ends a fast. However, with other factors taken into account, the answer is not quite black-and-white.

“So we have theory, and we have practice. And a lot of these things haven’t been researched in the academic world yet,” Samefko Ludidi, a nutrition scientist, told The Epoch Times.

“No food intake for at least 14 hours is when the mechanisms of intermittent fasting come into play, the additional benefits of your blood glucose metabolism decreasing, and your fat-burning capacity will start to take over,” said Ludidi.

Autophagy

Autophagy is a process of breaking down and recycling damaged cell structures that kicks in during slightly longer periods of fasting, typically after 20–24 hours, said Ludidi. Fasting for longer durations, up to 48 hours, can further enhance autophagy. However, he pointed out that more is not always better, as fasting for more than 48 hours may not provide significant additional benefits.

Exploring the Gray Areas

Given that the definition of what breaks a fast can vary based on your goals—whether they’re ketosis and weight loss, autophagy, or metabolic health—it’s important to consider common foods and drinks that fall into the gray area.

Coffee and Tea

Black coffee does not contain calories or sugar, making it safe to consume during fasting, said Ludidi. However, he explained that there is a possibility that black coffee may trigger cortisol and a stress response, potentially leading to an increase in blood sugar levels. This effect of black coffee on blood sugar levels may vary among individuals. Still, it will likely not directly spike blood sugar and is therefore considered safe during fasting. Black, green, and herbal teas without sugar or milk are also considered safe during fasting, he noted.

What About Cream or Sugar?

Adding fats such as full-fat cream, coconut oil, butter, or MCT oil, a popular supplement made from medium-chain triglycerides, to your coffee breaks the fast in terms of calorie restriction. However, adding fats can still keep you in ketosis and fat-burning mode if that is your goal. It is essential to differentiate between fasting (no calorie intake) and staying in a ketogenic state (low sugar metabolism) when it comes to adding fat to your coffee or tea, said Ludidi.

“If there is no food intake, then we’re still speaking about fasting. But if we’re going to add nutrients, such as fats, then we’re not fasting anymore, but we can still stay in that desired ketogenic state. If we add sugars instead of fats, then we will immediately get kicked out of ketosis. And we won’t enjoy the benefits of that metabolic switch, as it were, anymore.”

So, if ketosis and weight loss are your goal, adding additive-free fat to your coffee will not end your fast. It can even help extend your fasting window.

“If you’re on a fasting protocol and you feel you need some energy from nutrients, add some fats. Because in that way, you will at least stay in an upregulated fat-burning mode, and sugar burning will not take over, which is something that we want to stay away from because that upregulated fat-burning mode helps you to burn fat, including body fat, leading to weight loss in the end.”

Vitamins and Lemon Juice

Vitamins, including fish oil supplements containing fat or those with a rice bran or gelatin filler, are a bit of a grey area. Ludidi views them from a theoretical versus practical perspective.

“The question remains to what extent in everyday practice does a very small amount of carbs truly affect your glucose metabolism? So there is this theoretical framework, and theory [that] says fasting, strictly speaking, is just no intake of any calories, energy, fats, carbohydrates, and proteins, nothing at all. That’s theory,” he said.

“Personally, I believe that a very small amount of carbohydrates, as you could probably find in a squeeze of lemon juice, is not going to mess up your metabolism,” he added.

Ludidi explained that the total amounts of sugars and fats present in vitamins are very modest and will not kick you out of ketosis straight away. He pointed out that there is a reason you are still allowed a small amount of carbohydrates on a ketogenic diet. The keto diet generally allows for up to 50 grams of carbohydrates per day, as this is when insulin secretion is significantly reduced and your body remains in a catabolic state.

“The whole discussion about having carbs or not during fasting has to do with, mainly, being in ketosis. The amounts that we are speaking about in lemon juice or in vitamin pills is way less than the 10, 15, or even 20 grams of carbohydrates,” he noted.

Electrolytes

Electrolytes are just salts that do not contain calories and are fine to consume during fasting, said Ludidi. Not only are they safe during fasting, but they can also help with hydration and control hunger sensations during prolonged fasts.

“There are two advantages of having electrolytes—especially during prolonged fasts that last longer than 16 or 18 hours,” he said.

“One, electrolytes do not contain energy, no calories, no proteins, no fats, no carbohydrates, so you will still remain in the fasted state. And two, [electrolytes] can help you to control that intense desire for food during a prolonged fast,” Ludidi noted.

He stressed choosing electrolyte mixes without added sugars or caffeine.

“Go for very clean electrolyte mixes that only contain the electrolytes themselves, nothing else.” he said.

Artificial Sweeteners and Sugar Alcohols

Artificial sweeteners and sugar alcohols should be avoided during fasting, said Ludidi.

“The body could respond to that sweet taste by producing insulin to take up the sugars, which are not real sugars, and they don’t have the same effect as sugars,” he said. “But, they [non-nutritive sweeteners] could trigger an insulin response, [and] thereby also modulate or interfere with the fat and sugar-burning capacity that you’re playing with during intermittent fasting.”

If metabolic health is your goal for fasting, an increase in insulin levels may be counterproductive and break your fast.

“I would stay away from all kinds of artificial sweetness,” said Ludidi.

Protein Powder and Collagen

Protein powders, including those without sugars or additives, and collagen powders and supplements, will pull you out of your fast, said Ludidi. Proteins contain amino acids that can be converted into energy, thus interfering with fasting.

“My recommendation is if people want to use protein shakes because they train a lot, or if people want to use collagen supplements, then just do it, let’s say, 15 minutes before you break your fast. In that way, you can still benefit from the rapid gastric emptying,” said Ludidi.

Chewing Gum

Chewing gum during fasting is ultimately a personal choice, and the trace amounts of artificial sweeteners or carbs released while chewing are unlikely to interfere with fasting. Ludidi explained that many people are often conscious of their breath while fasting, and it can provide a sense of security and freshness, outweighing the risk of breaking the fasted state.

“I doubt that this is going to interfere. So if it makes you more secure, have your gum,” he said.

What About Bone Broth Fasts?

If your goal is to trigger autophagy with a longer fast, sipping on bone broth will not significantly interfere, according to Ludidi. He explains that the trace amounts of amino acids in bone broth are unlikely to disrupt the fasting state.

“Personally, I believe that if you go for a 24-hour fast or a 36-hour fast, you could easily do that also drinking bone broth. It’s not going to overrule your complete fasting protocol. The amount of energy you get out of the broth is not even measurable in kilo-calories,” he said.

Fasting Best Practices

If you’re seeking to adopt a fasting regimen or gain more clarity on your current protocol, it’s helpful to understand how to build up hours of abstinence from food. It’s not always best to jump right in.

“One important message here is that more is not always better. People tend to think that if one hour is good and 16 hours better, then 72 hours is the best. But more is not always better. Always listen to the signals that the body gives,” said Ludidi.

Ludidi recommends building your body up for more extended periods of fasting instead of jumping right in with a full-day fast. He suggests starting with 14 hours. Then, the following month, increasing to 16 hours, then 20, and so on, reaching a full 24 hours by the third month. He pointed out that most people are already engaging in some window of fasting without realizing it. For example, a late morning Saturday brunch.

“You'd rather fast for 20 or 24 hours once per month on a continued schedule year-round than try to push yourself for 96 hours. Because then you’re not reaping the benefits from fasting, but you’re just abusing yourself. You should do this [fast] from a self-care standpoint, not from a punishment standpoint,” he said.

How to Break a Fast

Understanding what to put on your plate when it’s time to eat again is also important, Ludidi noted. When reintroducing foods after a fast, the order in which you consume macronutrients is something to be aware of to ensure an easy transition for your digestive system. The best way to break a fast is to start with fats or proteins and introduce carbohydrates later to avoid digestive discomfort.

Introducing carbohydrates could lead to fermentation, bloating, and abdominal discomfort, and suggests starting with fats or proteins, Ludidi said. Then, introducing carbohydrates only during the second meal. He noted that fats are usually very well tolerated.

Ludidi recommends starting with a small portion of eggs and meat or a very small salad with eggs, fish, or meat. Two hours later, he suggests introducing carbohydrates with your main course to allow your gastrointestinal system to start working again, especially if you go for longer fasts.

There is little, if any, existing research on the subject of what breaks a fast, according to Ludidi.

“The question is whether it’s worth putting [in] all that research money to investigate these tiny, tiny details. It would be interesting from a practical point of view because people have these questions. But, we cannot clearly say that indeed vitamin pills or lemon juice with a tiny bit, or maybe half a gram, of sugar kicks you out of ketosis or interferes with your fasting protocol,” he stated.

When it comes to what breaks your fast, you can consider the contents of the food and drinks and apply them to your goals. Check for carbohydrates, any forms of sugar, protein, fat, and the overall calorie content. Then, ask yourself whether it will break your fast.