Will Bulletproof Coffee Break Your Fast?

I'm not a fan of adding oil to coffee. Here's why:

Will it break my fast if I add cream to my coffee? What if I add coconut oil to my coffee? What about Bulletproof coffee?

  • 1 tbsp. of half-and-half cream: 20 calories, 1.7 g fat, 0.6 g carbs, and 0.4 g protein
  • 1 tbsp. of coconut oil: 120 calories and 14 grams of fat

Even if you put a splash of cream in your coffee you will still be okay. Fasting works because it keeps your insulin levels low enough to allow fat burning (oxidation) to occur.

Coconut oil will not cause your insulin levels to rise. So technically, yes, you can have the coconut oil during your fast and it won’t elevate your insulin levels.

If you start eating spoonfuls from the jar of coconut oil, it is unlikely you will be in caloric deficit by the time you finish your fasting and feeding period — and therefore, you will not lose fat! Also, you must not forget to count this coconut oil toward your total calories and your fat macros for the day.

Here’s the problem. Are you tracking these calories and macros? When you break your fast, you must be prepared to eat 120 fewer calories and 12g less fat. If you aren’t taking these calories into consideration, it may explain why you are not losing fat with the intermittent fasting system. I've noticed that the people following my Fat Loss Fast System who gain fat instead of losing fat are always the ones who dump coconut oil into their coffee and into their skillets at every meal. Be careful, dietary fat packs 5 more calories per gram than carbs and protein... so take my advice and use dietary fat as your caloric buffer if you want to get results and stop using the "eat fat to lose fat" mentality as an excuse to over-consume dietary fat.

Quite frankly, I’d rather not include coconut oil in my fast, staying as close to zero calories as possible so I can benefit from fat oxidation and then indulge during my eating window on all my permitted calories and macros! Besides, fasting has a suppressive effect on hunger, so your need to eat something is purely psychological. And once you eat something, it will stimulate your hunger! So think twice! Grab a calorie-free drink instead!

Is Bulletproof coffee good or bad? Here's my opinion:

I'm not a coffee drinker, but if I were, I personally wouldn't add coconut oil or butter to it. Here's why...

  1. Although fats have no effect on insulin, consuming these “extra calories” are not without consequence. If you spike your coffee with butter and coconut oil, then you must subtract upwards of 456 calories and 46g of fat from your calorie allowance. Failure to track these calories will result in weight gain.
  2. Furthermore, research suggests spiking your coffee with coconut oil and butter may be boosting hyperlipidemia in otherwise healthy individuals. It would be a good idea to establish your baseline with your physician before you start dumping oil and butter into your coffee... and then reassess your lipid levels regularly.
  3. Lastly, if you want to burn stubborn fat, you need to be fasted. Triglycerides, just like insulin, will inhibit HSL (Hormone Sensitive Lipase), which is why low carb diets don't help you lose stubborn fat.
  4. p.s. You can argue with me until the grass-fed cows come home... but I won't be adding oil in my coffee, ever. Do what works for you. If you still don't want to listen to me, then listen to Martin Berkhan. He sums up everything I just wrote in 2 sentences.

berkhan oil in coffee

Video Blog: 


Dr. Sara Solomon is the creator of the Fat Loss Fast System about Intermittent Fasting and Flexible Dieting. She has degrees from McGill University in dentistry (DMD) and physical therapy (B.Sc. PT). She is also a CrossFit Level 1 Trainer, ACE personal trainer, NASM fitness nutrition specialist, Mad Dogg Spinning Instructor, Certified Level 2 Buddy Lee Jump Rope Trainer and Ambassador, a Team Bodybuilding.com and BSN athlete, and a retired PRO Fitness Model. Her passion is teaching others how to fuel and move well.


  1. Sara I love your Friday videos (and all others ie. Workout and recipe ones)! This one is great because people are always asking me about IF and make the comment “I need cream in my coffee, so I couldn’t do IF”. Well now I have the info to tell them that they can do IF and still enjoy their coffee! Great info. Your system is slowly changing my life for the better! I love being a member on your site!

  2. Hi Dr. Sara!

    I’m so glad you posted on this topic! I started putting coconut oil in my coffee when I began intermittent fasting because I was afraid the fasting would wreak havoc on my fertility. I’ve had issues with my cycle in the past and had to see a doctor to get it straightened out. BUT I’m wondering if it would make fasting easier if I cut out the coconut oil altogether because I’m still getting very hungry around the 14 hour fasted mark even though I’ve been at this for almost a year. Would you mind sharing some thoughts about women looking to conceive eventually while intermittent fasting or could you please point me in the direction of info. about it? Thank you for all you do!

  3. Thanks for this video! This is the exact topic question I had been looking for an answer to. I’ve been trying out the IF 16/8 for about a month now and Just started following you (subscribing that is…not like a creepy stalker). I’m feeling results! Thanks Dr. Sara! (P.S. Your videos are hilarious and your makeup is always perfect!)

  4. I find your input very useful in helping me come to my own conclusion about having a healthy lifestyle. My question is, have you noticed an effected on your menstrual cycle especially with the IF and your workout style? Stressors like low body fat, low caloric diets and even BC pills have been associated with lady-timing. Since I imagine you have worked along side many female fitness models that have been through it all and may have had troubles yourself, I am curious to know if the FLFS may help regulate hormones with its limited stressor effects of low caloric dieting and long workouts. I would like to know your input in the matter.

  5. Thank you for the Q&A, I was hoping I didn’t have to give up my beloved cream in my coffee. I was trying a few drops of Stevia, but it just wasn’t the same. Love your videos and your humor.


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