Can You Drink Coffee While Fasting?

Intermittent fasting has been increasingly used for weight loss and touted benefits on metabolic health, such as decreases in cholesterol or improvements in insulin response. The fasting period is typically either alternate days or time-restricted, meaning meals are either restricted on “fast” days (about 25% energy consumption) or a prolonged overnight fast after cessation of eating around early afternoon.

Key takeaways:
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    Most coffee consumption during intermittent fasting is OK, especially black coffee, such as drip coffee or espresso.
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    Regular coffee consumption is associated with numerous benefits, some of which, like the regulation of appetite, can increase the success of intermittent fasting.
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    Caution is necessary with coffee additives during intermittent fasting. This is because some high caloric additives may increase blood sugar, with associated insulin response, and may negate the benefits of fasting, such as those on body weight.

Will coffee break your fast?

About 7 in 10 adults in the US consume the equivalent of 280 mg of coffee daily. Caffeine, the main ingredient in coffee, also comes with short and long-term beneficial effects such as improved alertness, quicker reaction time, and reduced risk of Parkinson’s disease, Alzheimer’s disease, and gout. Coffee intrinsically contains no calories and, thus, is OK to drink while intermittent fasting. All types of coffee, like americano, espresso, drip, French, decaf, black, iced, hot, etc., without additives such as milk, creamer, or sugar, don’t affect intermittent fasting. Au contraire, studies show that these drinks regulate appetite and energy intake and, thus, complement intermittent fasting.

Bulletproof coffee

Bulletproof coffee is coffee with butter and a medium chain triglyceride (a form of fat). From a caloric perspective, bulletproof coffee can contain up to 500 calories, about as much as a medium Frappuccino — from fats, not carbohydrates. Thus, drinking bulletproof coffee while intermittent fasting goes against the gist of the fast, though you can drink it during your “feast” days if you’re on an alternate fasting day.

Flavored coffee

Most flavored coffee, such as hazelnut, vanilla, or caramel, is artificially flavored. That means that it has no extra carbs, sugars, or calories, making them equivalent to black coffee. Thus, flavored coffee is OK to consume while fasting. However, some studies show evidence that artificial flavoring may increase hunger and your risk of Type 2 diabetes.

Coffee with cream, sugar, milk, and other additives

Close to half of coffee drinkers in the US prefer their coffee black and without additives. For the other half, the sky's the limit. This other half indulges in various types of milk, sugar, creamer, coffee, and artificial sweeteners. Of all possible additives, creamer and whole milk have the highest number of calories. In contrast, fat-free creamer, fat-free milk, and milk alternatives have fewer calories. Because one sugar packet contains about 15 calories, you can see how quickly calories add up if you use multiple sugar packets. Ultimately, if you’re on a fasting day or are “after-hours”, try to stick to artificial sweeteners such as Stevia or Splenda or low-calorie additives such as fat-free creamer or milk alternatives such as almond milk. However, be mindful that studies show that artificial sweeteners increase appetite. Therefore, a “sugar spike” and the associated insulin response may also make you hungry.

What coffee can you drink when fasting?

While fasting, try sticking to black coffee varieties such as espresso or drip coffee. If it tastes too bland, you can add various spices or a splash of alternative milk, such as almond or soy. Another way to enhance the flavor is by adding a dash of coconut oil or fat-free creamer.

What else can you drink while fasting?

You’re not limited to coffee while fasting. You can drink plain water or sparkling water or go wild and try flavored water varieties. You can also try drinking tea as it comes in numerous varieties and flavors, unlike coffee; therefore, the taste is typically more palatable without additives.

Benefits of drinking coffee while fasting

Caffeine, the main ingredient in coffee, is associated with countless benefits. These include:

  • Improved mental alertness
  • Improvements in vigilance and reaction time
  • Improved athletic performance
  • Mitigation of sleep deprivation
  • Lowering all-cause mortality
  • Reducing risks of Alzheimer’s disease, gout, Parkinson’s Disease, Type 2 diabetes
  • Lower incidence of strokes

There has also been considerable research to explain how caffeine exerts health benefits. Some recent hypotheses include enhanced autophagy, where the body breaks down and repairs damaged cells, as well as moderates gut microbiota and the gut-brain axis.

The risks of drinking coffee while fasting

Caffeine is ultimately a stimulant and can lead to abuse and withdrawal. Furthermore, especially if consumed during a fast on an empty stomach, it may lead to gastrointestinal upset, such as diarrhea or nausea. Excess caffeine consumption can also lead to palpitations or tremors. From an additive standpoint, creamers, flavoring, sugar, etc., used to make coffee more palatable may make you feel hungrier during a fast and possibly affect blood sugar levels. This may ultimately lead you to give in and break the fast, possibly negating any effects from diet and body weight loss.

Can you drink coffee when fasting for blood tests?

The most common lab tests that necessitate fasting are glucose and those related to blood lipids such as cholesterol. Most of these tests require overnight, or about 12 hours of fasting. Thus, it’s ideal to stick to water only until your blood draw. However, it is unlikely that black coffee would affect lab test results, though all additives may likely alter results. Therefore, if you’re planning on drinking coffee while fasting for lab work, make sure it’s black.

Can you drink coffee while fasting for an ultrasound?

Fasting for an ultrasound is mainly recommended for diagnosing gallstones, as stones in the gallbladder are best seen if it is distended and the stone is surrounded by bile. Fasting for at least eight hours ensures that the gallbladder will be full. Both regular and decaffeinated coffee causes the gallbladder to contract and release bile, which is why doctors recommend zero coffee consumption while fasting before an abdominal ultrasound — particularly if the goal is to diagnose gallbladder disease.

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