It's no secret that intermittent fasting is a popular go-to weight loss strategy. However, it can definitely shake up your daily routine. If you're used to enjoying a cup of joe every morning, you might be wondering, "Can you drink coffee while intermittent fasting?" And is there a specific type of coffee that does (and doesn't) break a fast? The hype is real.
Following an intermittent fasting schedule may help you lose weight short-term, and could also improve blood pressure, LDL cholesterol levels, and insulin resistance, per a study published in Nature Reviews Endocrinology. That said, the process of fasting can be restrictive and make you question everything you're putting into your body—including that delicious seasonal drink from Starbucks you can't get enough of.
So, is coffee off-limits while intermittent fasting? You're probably curious if it's okay to sip some java while you're riding out your fasting window, or whether it's best to enjoy it only during your eating windows. It's also natural to wonder if coffee *really* has that much of an impact on your ability to lose weight. Here's what dietitians say.
Meet the experts: Barbie Boules, RD, is a nutritionist and certified health coach at Barbie Boules Longevity Nutrition. Roxana Ehsani, RD, is a nutritionist in Miami, Florida. Scott Keatley, RD, is a nutritionist and member of the Academy for Nutrition and Dietetics. Keri Gans, RD, is a New York-based registered dietitian and author of The Small Change Diet.
Can I have coffee while fasting?
Because a cup of black coffee is fat-free and almost no-cal, it won’t interrupt your fast, says nutritionist and certified health coach Barbie Boules, RD. Your regular coffee variations and add-ins—like sweet flavors, syrups, milk, and sugar—will likely cost you fat and calories, which typically means you are no longer fasting, she says. So, your usual order is (sadly) probably off-limits during your fasting window. The more calories you feed your body, the more outside fuel it has to use as energy, which means it won't utilize the glucose stored up in your fat cells, in theory.
Does milk in coffee break a fast?
Unfortunately, yes. "Adding milk—whether it's cow’s milk, oat milk, almond milk, or creamer—will technically break your fast, as milk and cream does have calories," says Roxana Ehsani, RD, a nutritionist in Miami, Florida. This means that macchiatos, lattes, flat whites, cappuccinos, mochas, and proffee don't make the cut.
When you add milk to your coffee, “the body will use the energy and nutrients contained in the milk and coffee and use less of the body's internal energy stores,” says dietitian Scott Keatley, RD. At that point, the fast has technically been broken, he says.
If you want to enjoy coffee but remain in a fasted state, your best options are decaf or regular coffee, classic espresso, or an Americano (espresso and hot water), says Ehsani. You can have any of them hot or iced, and instant coffee counts, too, she adds.
“The general rule for what to put in your coffee is that it basically has zero calories,” says dietitian Keri Gans, RD, author of The Small Change Diet. “In other words, try and enjoy it black.” But if having your coffee plain isn't your thing, try adding a sprinkle of cinnamon, touch of nutmeg, a tiny bit of cocoa, a sugar alternative, or low-calorie sweetener like Splenda.
Can coffee enhance the effects of intermittent fasting?
Since coffee makes you feel revved up, it’s only natural to wonder if caffeine can potentially boost your metabolism while fasting. The research on this is mixed, though—caffeine intake may promote weight loss and body fat reduction, one study found, but other research suggests caffeine has a small effect on your metabolism. Ultimately, while coffee *might* increase your metabolism slightly during a fasting state, it's unlikely that coffee will do much, if anything, to give you a weight loss boost, Keatley says.
Still, your caffeine habit may serve up other benefits unrelated to the scale. There's a clear association between increased coffee consumption and a lower risk of developing certain conditions such as cardiovascular disease (CVD), type 2 diabetes, and liver cancer, according to a 2021 study published in Advances In Nutrition. (Researchers found that coffee drinkers who drank between three to four cups a day had the greatest reduction in CVD risk.) Drinking two to three cups of ground, instant, and decaf coffee per day may also be linked linked to a longer lifespan, per a 2022 study in European Journal of Preventive Cardiology.
Of course, this doesn't mean that drinking coffee is an overnight fix for serious health issues. Like many topics in the nutrition world, more research is needed to determine the benefits, and it's wise to talk to your doc before drastically increasing your coffee intake for the potential health perks or otherwise.
What To Eat And Drink While Intermittent Fasting
Water, including with fruit or a squeeze of lemon, is okay while intermittent fasting, Boules says. You can also reach for unsweetened tea, which has zero calories when you sip it plain. “The whole idea behind the alleged health-promoting benefits is actually fasting (i.e., zero calories or energy intake),” says Boules. “If you’re consuming something caloric during ‘fasting hours’ in the form of sweetened beverages, juices, or smoothies, you're not fasting.”
Remember, the whole concept of intermittent fasting relies on a prolonged, uninterrupted period of not consuming any calories—but obviously, this is super restrictive, so you may want to pick a specific schedule (like the 16:8 method, for example) and only try it short-term. “The most important question to ask is, ‘Why am I fasting?’ If it's for physical health reasons, there are better ways [to achieve your goals], and if it's for spiritual or mental health reasons, pick the path that best suits your needs," Keatley says.
Frequently Asked Questions
Can you eat anything while you fast?
Technically, no—but feel free to get some sugar-free gum or hard candy with sugar alcohols or non-nutritive sweeteners like xylitol, which Boules says don’t affect your calorie intake or blood glucose in the way that regular sugar does, so you won't be breaking your fast. (Note: Artificial kinds could cause some bloating or mild GI upset).
Should I start drinking coffee when I fast?
The short answer is no. You don’t want to start a coffee-drinking habit just to soothe your hunger if you're doing intermittent fasting. But if you're a regular caffeine consumer and want to continue your morning brew, it likely won't affect you too much, says Boules, especially if you're choosing a low-calorie option.
Can I use supplements in my coffee when I fast?
Unfortunately, buzzy supplements such as collagen powder or MCT oil shouldn't be added to your cup of coffee while you're intermittent fasting, since even one serving counts as calories, says Gans. That said, if you're already taking a supplement or medication and want to try intermittent fasting, always consult your doctor to determine the best path forward.
Korin Miller
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamour, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.
