Intermittent fasting has become an increasingly popular diet strategy for weight loss and health improvement. During intermittent fasting, you restrict your eating window to certain hours of the day and fast the rest of the time. One question that often comes up is whether you can drink bulletproof coffee during your fasting window on an intermittent fasting plan.
What is intermittent fasting?
Intermittent fasting involves alternating between periods of fasting and eating. Rather than restricting what you eat, it restricts when you eat. There are several different intermittent fasting schedules, but some of the most common include:
- 16/8 method: Fast for 16 hours per day and restrict eating to an 8-hour window.
- 5:2 diet: Eat normally 5 days a week and restrict calories to 500–600 two days a week.
- Alternate day fasting: Fast every other day.
- The Warrior Diet: Eat small amounts of raw fruits and vegetables during the day and one huge meal at night.
- Eat-Stop-Eat: Do a 24-hour fast once or twice per week.
No matter which method you choose, the goal of intermittent fasting is to reduce your overall calorie intake to promote weight loss and health improvements.
What is bulletproof coffee?
Bulletproof coffee is a high-fat coffee drink intended to help boost energy levels, mental clarity, and fat loss. It was created by Dave Asprey and consists of just three ingredients:
- Brewed coffee
- Grass-fed butter or ghee
- MCT oil
The butter and MCT oil provide a mega-dose of fats that can help curb appetite and give you lasting energy. Each ingredient also provides potential health benefits:
- Coffee: Contains antioxidants and caffeine to increase energy.
- Butter/ghee: Provides fatty acids like butyrate.
- MCT oil: May increase ketone production and fat burning.
Can you drink bulletproof coffee while intermittent fasting?
Whether or not you can drink bulletproof coffee during intermittent fasting depends on your specific goals and the type of intermittent fasting protocol you are following.
For weight loss
If your main goal with intermittent fasting is weight loss, avoiding bulletproof coffee and other high-calorie beverages may be best.
The basis of intermittent fasting for weight loss is reducing your overall calorie intake by limiting eating to a few hours per day or fewer days per week. Drinking high-calorie beverages like bulletproof coffee can easily add a few hundred extra calories during your fasted state, which could negatively impact weight loss.
For example, a typical bulletproof coffee made with two tablespoons each of butter and MCT oil contains over 450 calories. Consuming 450 extra calories from high-fat coffee could easily wipe out a large chunk of your calorie deficit from intermittent fasting.
If losing weight is your priority, stick to low-calorie drinks like water, unsweetened tea, or black coffee during your fasting window.
For blood sugar control
Intermittent fasting may also improve blood sugar control by reducing insulin resistance. Insulin is the hormone responsible for shuttling sugar from the bloodstream into the cells.
Some research shows that fasting could help improve insulin sensitivity, allowing your body to more efficiently transport glucose out of the blood and into tissues where it can be used for energy.
Drinking high-fat coffee drinks could impair some of these benefits by stimulating insulin secretion. For example, one small study in 12 healthy men showed that consuming bulletproof coffee stimulated insulin secretion, although it did not change blood sugar levels.
To maximize the benefits for blood sugar control, you may want to avoid bulletproof coffee and stick to low- or no-calorie beverages during your fast.
For ketosis
One of the proposed mechanisms behind intermittent fasting is that it can promote ketosis by depleting liver glycogen stores. Ketosis occurs when your body starts burning fats for fuel instead of carbs.
Some proponents of bulletproof coffee claim that it can help boost ketone levels during intermittent fasting by providing pure sources of fat like MCT oil and butter.
MCT oil, in particular, contains fatty acids that are transported directly to the liver, where they can be immediately used for energy or ketone production.
However, there is very limited research examining how bulletproof coffee may impact ketosis. One small study found MCT oil was associated with increased ketone levels compared to long-chain triglycerides from olive oil.
More research is needed on how bulletproof coffee specifically affects ketone levels and ketosis.
For other health benefits
In addition to weight loss and blood sugar control, several other health benefits have been associated with intermittent fasting, including:
- Reduced inflammation
- Increased longevity
- Improved heart health
- Enhanced brain function
- Protection against disease
However, it’s unclear if drinking bulletproof coffee during your fast impacts these other potential benefits.
More research is needed to determine if bulletproof coffee supports or impairs other health benefits linked to intermittent fasting.
Should you have bulletproof coffee while intermittent fasting?
There are a few factors to consider when determining if you should drink bulletproof coffee during intermittent fasting:
Your goals
Consider your specific goals and reason for intermittent fasting. Are you fasting for weight loss, blood sugar control, or other health benefits? How you answer this question can help guide your decision.
Calories
Bulletproof coffee is very high in calories, packing in over 450 calories per serving. If limiting calorie intake is important for your goals, avoiding high-calorie beverages is likely best.
Hunger management
Many proponents of bulletproof coffee claim it can kill hunger. While research on this is lacking, the satiating fats in bulletproof coffee may help manage hunger during the fasted state for some people.
Type of fast
More flexible intermittent fasting protocols like the 16/8 method or Warrior Diet may be able to accommodate bulletproof coffee better than stricter fasts like alternate day fasting.
Tips for using bulletproof coffee while intermittent fasting
If you do choose to use bulletproof coffee during intermittent fasting, here are some tips to get the best results:
- Stick to just 1–2 servings per day max.
- Measure ingredients carefully to avoid excess calories.
- Use grass-fed butter or ghee.
- Increase MCT oil slowly to minimize digestive issues.
- Avoid added sugars or creamers.
- Wait to add bulletproof coffee until at least a few hours into your fast.
- Consider lower-calorie modifications like adding just coconut oil or MCT oil to your coffee instead of butter.
Other beverages to enjoy
If you choose to avoid bulletproof coffee while intermittent fasting, there are many other low-calorie beverage options to enjoy during your fast:
- Water
- Unsweetened tea
- Black coffee
- Green tea
- Sparkling water
- Bone broth
- Apple cider vinegar drinks
- Mineral water
Aim to stay hydrated with non-caloric beverages and save higher calorie drinks like bulletproof coffee for your eating window.
Should you have bulletproof coffee before working out while intermittent fasting?
Deciding whether or not to have bulletproof coffee before working out while intermittent fasting depends on the type of training:
Low- to moderate-intensity workouts
For lower-intensity workouts like walking, jogging, yoga, pilates, etc. having bulletproof coffee beforehand is unlikely to offer any benefit. Your body can readily tap into stored fat for fuel during shorter, lower intensity workouts.
High-intensity workouts
For tough high-intensity workouts or long endurance training sessions, having a bulletproof coffee before exercise may provide some advantage.
The caffeine in coffee can enhance alertness, focus, and performance. The fats from MCT oil and butter offer an immediate source of energy.
However, for most people doing intermittent fasting, working out in a fasted state is completely fine. Your body is quite good at adapting to using fat for fuel. Some may even prefer fasted workouts finding they have more energy and feel lighter when training without food.
Try it
Experiment to see if having a bulletproof coffee vs. fasting before your workout gives you the best results and performance. Assess your energy levels, hunger, workout recovery, and any other metrics important to you.
Keep in mind the extra calories from bulletproof coffee can reduce the calorie deficit from intermittent fasting, which may slow weight loss.
Bulletproof coffee alternatives before a workout
If you want to break your fast before working out but don’t want to consume the high amount of calories in a traditional bulletproof coffee, some lower calorie options include:
- Black coffee: Provides caffeine for energy.
- MCT oil: Quick source of fatty acids for fuel.
- Whey protein powder: Isolate provides protein to help minimize muscle breakdown.
- BCAAs: Essential amino acids support muscle recovery.
- Green tea: Provides caffeine plus antioxidants.
- Half a banana: Easy to digest carbs.
The bottom line
While intermittent fasting does restrict when you eat, there is flexibility when it comes to what you drink during your fasting periods.
Drinking high-fat bulletproof coffee can add a significant number of calories during your fast, which may inhibit weight loss and some other potential benefits.
However, bulletproof coffee may be accommodated in more relaxed intermittent fasting protocols. The fats can promote ketosis while the caffeine provides energy.
Pay attention to your body, goals, and schedule to determine if bulletproof coffee fits into your intermittent fasting lifestyle.
Prioritize low- or no-calorie beverages like water, plain tea, or black coffee to maximize health benefits.