Does mushroom coffee break a fast? The honest answer depends on which fast
Short answer: a serve of Mello Mushroom Coffee is about 15 calories, almost all of it from the MCT oil and coconut milk in the blend, and the matcha is about 25 calories. Whether that breaks your fast depends on what you mean by fasting. Some fasts are broken by anything at all; some allow small amounts of fat; some are only about time between meals. Here is the plain version, by type, so you can decide for yourself rather than take a brand's word for it.
Mushroom coffee calories and ingredients
Mushroom Coffee is a blend of six mushrooms, instant arabica coffee, MCT oil and coconut milk. Per 6g serve the pack lists 15 calories, about 1g of fat, less than 1g of carbohydrate, no protein and no added sugar. Mushroom Matcha is the same six mushrooms, blue spirulina, Himalayan pink salt and ceremonial grade Japanese matcha, at about 25 calories per serve with about 1g of carbohydrate and no added sugar. Neither contains sweeteners. Both have about 48mg of caffeine. Those are the numbers everything below rests on.
Does mushroom coffee break a clean fast? Technically, yes
If your rule is water, black coffee and plain tea only, then anything with calories counts, and 15 calories from fat is not zero. The same is true of a splash of milk in a regular coffee, which most strict fasters already avoid. If you fast this way, have your mushroom coffee at the start of your eating window rather than during the fast, or drink the cold brew style version of the matcha with water and accept 25 calories, which some strict fasters do and some do not. We are not going to tell you 15 calories does not count when your own rule says it does.
Mushroom coffee on a keto or fat tolerant fast
Many people who fast for metabolic reasons, or who follow a keto pattern, allow small amounts of fat during the fasting window on the reasoning that fat does not meaningfully raise insulin the way carbohydrate and protein do. This is the logic behind putting butter or MCT oil in coffee. Mello Mushroom Coffee already has MCT oil and coconut milk in it and under 1g of carbohydrate, so it fits comfortably inside that rule. If you already drink a fatty coffee during your fast, the mushroom version is the same category with a lower caffeine dose.
Mushroom coffee and intermittent fasting (16:8)
Most people doing 16:8 are managing when they eat, not chasing a specific metabolic state, and they treat black coffee and tea as free. Whether 15 calories crosses your line is a personal call. A reasonable middle position that a lot of our customers take: mushroom coffee is fine in the fasting window, but no milk on top until the eating window opens. That keeps it at 15 calories rather than 100.
Does mushroom coffee affect autophagy? The honest answer
If your fast has a specific physiological goal, the honest position is that the research on which nutrients and amounts interrupt those processes is unsettled, and we are not going to pretend a coffee brand can settle it. Ask the person who designed your protocol what their rule on fat calories is and apply it. Fifteen calories of mostly fat is the number they need.
Why people drink mushroom coffee while fasting
Two practical reasons come up again and again. First, appetite: coffee generally blunts hunger, and a lower caffeine coffee with a little fat in it tends to do that without the jittery, empty stomach feeling a strong black coffee can give some people during a fast. Second, the crash: a smaller caffeine dose means a smaller drop later in the morning, which matters more when there is no breakfast underneath it. Both of those are caffeine and fat arithmetic, not mushroom claims. The six mushrooms in the blend have long traditional use and early research behind them, summarised on our Cordyceps and other research pages, but nothing in that research is about fasting and we will not stretch it to fit.
What not to do with mushroom coffee during a fast
Do not stack it. Two serves is about 96mg of caffeine on an empty stomach, which is still under one flat white but noticeably sharper without food. One serve, then water, is the pattern that works. And if fasting is new for you and you feel light headed, shaky or unwell, that is a reason to eat, not a reason to have another coffee. Anyone with a medical condition, on medication, pregnant or breastfeeding should be talking to a GP about fasting at all, let alone about what to put in the coffee; our side effects guide covers who should be careful.
Does mushroom matcha break a fast?
If you want the cleaner number, the matcha blend has no added oil, but it is slightly higher in calories at about 25 because of the matcha and spirulina themselves. It is the better choice for people who find coffee harsh on an empty stomach, and it works well made with water only, which keeps it lean. Our guide to when to drink mushroom coffee covers the morning versus afternoon question in more detail.
Does mushroom coffee break a fast? The short version
About 15 calories a serve, mostly fat, under 1g of carbohydrate, no sugar. Breaks a strict water only fast by definition; fits a fat tolerant or keto fast; and for 16:8 it comes down to your own rule, with no milk until the eating window as the sensible compromise. Take the numbers, apply your protocol, and skip the brand that tells you their coffee is magically fast safe. Both pouches are 30 serves with a 30 day money back guarantee if it turns out not to suit the way you eat.