On the left: June / before beginning a keto diet     On the right: 3 days post fat-fasting.     I didn't take pre & post fat fast photos because ... I'm a dummy. 

On the left: June / before beginning a keto diet

On the right: 3 days post fat-fasting.

I didn't take pre & post fat fast photos because ... I'm a dummy. 


A Fat Fast is a type of fasting where you eat about 80-90% of your calories from fat while keeping your calorie intake low (between 1000-1200) and followed for no more than 3-5 days. 


This type of fasting is often recommended for those who are already keto-adapted (meaning someone who has been following a keto diet where carbohydrates are restricted to about 20-40 net grams a day and the body has begun producing ketones putting them into a state of ketosis) and has reached a weight loss plateau for more than 2-3 weeks. 

A fat fast can also serve the purpose of getting yourself back into a state of ketosis following a high-carb “cheat meal”.


Duh, someone who is not already fat adapted/ following a keto diet. 

Someone looking for a “quick fix”. Sure, you’ll drop some pounds over a 3-5 day period but if you do not follow through with restricting carbohydrates and keeping your daily caloric intake below a surplus then again, duh, you’re just going to add those pounds lost right back on. 

This should go without saying, but I do not and will not recommend a fat fast, (or any fast for that matter), to a client who has disordered eating habits such as someone who:

  • has a history of binge eating
  • has a fear of calories or has the disillusion of keeping their calories in too much of a deficit for extended periods of time or indefinitely 
  • has the propensity to “fly off the handle” if the scale bumps up a pound because you will gain back a pound or two following the lowest weight reached during a fat fast.


I experimented with a fat fast for 5 days last Thursday through Monday with the primary intention of practical application of a fat fast so I can arm my keto-clients with first hand experience. Additionally, I had celebrated my birthday with an ice cream “cheat-treat” so there was an added benefit for me to kick myself back into ketosis (assuming I was kicked-out following a high-carb indiscretion). 

*Note: I did not regularly check my blood-ketones the months prior my fat fast attempt. I follow a “keto-diet” but I do not feel the need to nerd out on myself and track my blood ketone levels. 


I typically fast intermittently, meaning 4-5 days a week I take in only a small amount of calories from fat in the morning and then eat the bulk of my daily calories between 2 and 9 pm. Therefore, I didn’t have much difficulty with the idea of having to restrict my calories (by 800-1000 calories) because during the fast I was still taking in the majority in a short window (between 2 & 9 PM).  I imagine if you are used to eating a solid 3 meals a day + snacking then the actual “habit” of eating would make restricting calories on a fast more challenging. 

Thursday, Day 1: I was fine until I got hangry around 8 PM. I did OrangeTheory in the morning.  

Friday, Day 2: I felt better about spreading my calories out throughout the day to avoid the hangry-episode. I did not workout on this day. 

Saturday, Day 3: Got pretty bored with my food choices and had a breakdown moment where I thought to myself, “why do I do this to myself?” Mostly was annoyed with myself for scheduling a fast over the weekend when I have more downtime and tend to eat out more frequently. Did 90 minute Hot Yoga on this day and felt good energy-wise.

Sunday, Day 4: Totally felt like I was in a good groove. Probably drank too much coffee on this day but I had a good distraction from food while spending the majority of the day at a Ski & Snowboard Expo. Did not workout on this day.

Monday, Day 5: Felt great energy-wise. Did OrangeTheory in the am. Felt like I could continue fasting for several more days (*not recommended to go longer than 5 days to avoid going into starvation mode and subsequent muscle loss). 



Each day began the same:



+ 1 tbsp MCT Oil 

+ 1-2 tbsp of heavy cream 

+ 1 tbsp CoffeeBooster 

= 25 - 35g fat / 225 - 315 calories 

PM Meal 1:

1-2 oz macadamia nuts 

= 20 - 40g fat / 180 - 360 calories

PM Meal 2:

This was the only meal each day where I added protein in the form of either bacon, prosciutto, or sashimi (salmon or tuna).

I added fat to this meal meet my daily calorie goal (1000-1200 calories)  in the form of macadamia nuts, avocado, and/or a small amount of cheese or nut butter. 

I drank 1.5 gallons of water each day and pretty much sipped on my morning coffee all day or had a second (or third) cup adding only heavy cream. I tracked my intake in My Fitness Pal on day 2, 3, and 4.  



I was kind of a bloated mess on the morning of day 1, (ice cream bloat + the end of Shark Week), so my starting weight of 152 was about 2-4 pounds heavier than my normal weight. I tend to stay between 147 and 151 pounds depending on the week. Guys don’t understand this but I know you ovulating ladies do: I get what I refer to as “two good weeks” per month followed by PMS week and Shark Week in which my weight goes up 4-6 pounds… like whoa. 

Day 1: 152 pounds

Day 2: 149.4

Day 3: 147.4

Day 4: 145.4

Day 5: 144.8

Day 6: 143.6

I am now 3 days post fat-fast and my weight this morning was 145 point something. Since Tuesday I have been “reversing” myself back up to the calorie intake I was set at before the fast as well as slowly adding protein back in each day.

And THAT is my fat-fasting in a <macadamia> nutshell

If you’re interested in starting a keto diet or a fat fast but unsure where & how to begin or if you're just looking for nutrition or fitness plan that works with your lifestyle you can contact me for more info on my 12 week guided programs. 

I’m taking on 2 more new clients this month, 10 in December, and 20 in January. If you want to wait to get started after the holidays you can Commit NOW to begin in JANUARY and you’ll get an extra 4 weeks of Nutrition Coaching! 

Shoot me an email and I'll get you set up with a nutrition or fintess plan aligned with your goals and lifestyle!

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