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Complete Guide to Fat Fast

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Table of Contents

Before I get to the details of what fat fast is and how to do it, I should mention that this is a tweaked version of the original. One difference is the decreased minimum intake of fat and the second is the reduced number of meals a day. Both of these are explained in this post and are just optional - it will be up to you which path you choose.

The Fat Fast is not a new concept, it has been around for many years. The first proponent of using fat fast to break through a weight loss plateau or "reset" a cheat day was Dr Robert Atkins himself in his best-selling book Dr Atkins New Diet Revolution.

In 2013 Dana Carpender, the best-selling author of books about low-carb and ketogenic diets, published her Fat Fast Cookbook. If you want to try the fat fast, you should get her book. It contains 50 delicious and easy to prepare recipes, enough to stay away from boring monotonous meals! Keep in mind that not all ingredients in her book are paleo-friendly and you may need to make small adjustments to fit your needs.

What Is Fat Fast?

Although most of you probably know how the ketogenic diet works, I'll give you a quick overview before I get to the fat fast itself. Ketogenic and other low-carb diets have been around for a long time. Most low-carbs diets, including the ketogenic diet, can are used for weight loss and offer numerous health benefits. In fact, very low-carb ketogenic diets have been used to treat neurodegenerative diseases such as epilepsy or Alzheimer's for decades. Currently, they are also shown to have potential use in cancer treatment.

We have all been told that all calories are the same no matter where they come from. This advice has been proven to be false and yet despite all the evidence, the guidelines still remain the same: "Exercise more, eat less and focus on eating low-fat foods." Sadly, I keep seeing this piece of advice on most packaged foods — just another reason to avoid them!

Complete Guide to Fat Fast

Here is the general rule that applies to the ketogenic diet: When you restrict carbohydrates to a certain level (20-50 grams of net carbs), your body starts producing ketones and you enter ketosis (ketosis is not the same as ketoacidosis which is dangerous).

Once you become fat-adapted, your body uses your fat stores and ketones for energy and you won't need to eat extra protein to spare muscle mass. This doesn't mean you should avoid protein — your protein intake should be adequate and based on your individual needs. Although your body still needs some glucose, it can produce it on demand via gluconeogenesis.

Fat Fast is a type of fasting often recommended for those who are already keto-adapted and reach a weight loss plateau. The idea is that you eat about 80-90% of your calories from fat while keeping your calorie intake low, up to 1000-1200 kcal a day. This fast should be followed for no more than 3-5 days. If you follow the fat fast for a longer period, you run the risk of getting your body into starvation mode, losing muscles and getting deficient in essential nutrients.

When you go on a fat fast and you are already keto-adapted, your ketone level will likely get very high (mine got as high as 3.2 mM) because most of the energy (that is limited to 1000-1200 kcal) comes from fats, and you begin burning your own body fat due to the calorie deficit and very low insulin levels.

Recent studies show that in terms of weight loss and muscle sparing, "traditional" fat fast (90% kcal from fat) doesn't seem to have more benefits than a fast with less fat and more protein. This doesn't mean that traditional fat fast doesn't work. It only means that even if you eat slightly more protein, you may achieve the same or better results. Since protein is the most sating macronutrient, it will help you keep hunger at bay during the fast.

Here's a simple calculation: the adequate protein intake from 1200 kcal for an average person is about 15-20% (or even more for physically active people and those with less body fat and more lean mass). Since you'll be eating ~ 5% or less calories from carbs on a fat fast, you will be left with 75-80% of calories from fat. Not a big difference from the "traditional" fat fast.

Studies from the 1950's and 1960's (first by Kekwick and Pawan,1 later by Benoit2) showed that a fat fast is best for fat loss and preserving muscle mass when comparing three diets (1000 kcal diet with 90% fat vs. 1000 kcal diet with 90% protein vs. 1000 kcal diet with 90% carbohydrates). However, these studies have been shown to be largely flawed. While Kekwick and Pawan admitted that participants may have been cheating and the study was poorly controlled, Benoit's results seemed to have been overexaggerated. In his study from 1965, Dr. Benoit compared results achieved in obese participants by putting them on a fat fast and on a complete fast. Interestingly, those following a fat fast experienced twice as much fat loss compared to those following a total fast during which they lost more muscle mass and less body fat. In later reviews of this study, some experts pointed out that the participants would have to have enormous energy expenditure to reach such weight loss results.

An excerpt from a review of studies from 2006 on protein-sparing effects of very low-carb diets:

"Because of metabolic adaptations to prolonged changes in diet composition, the results of such short-term studies cannot be applied to longer-term situations... Although more long-term studies are needed before a firm conclusion can be drawn, it appears, from most literature studied, that a VLCARB is, if anything, protective against muscle protein catabolism during energy restriction, provided that it contains adequate amounts of protein."

Keep in mind that prolonged calorie restriction with inadequate amount of protein can lead to deficiencies, muscle mass loss and a decreased BMR. That's why you shouldn't do the fat fast for more than 5 days. It's also important to mention that no study seems to take keto-adaptation / fat-adaptation into consideration. The body works differently for sugar-burners and those who are fat-adapted and the logical conclusion would be that fat-adapted people would lose less muscle mass during a fat fast.

When to Consider the Fat Fast

Here are the rules for when to follow the fat fast:

If you are already keto-adapted

Otherwise, it will be very difficult for you, as your body is not used to the ketogenic diet. If you are not keto-adapted, try following the ketogenic diet for 3-4 weeks and only use the fat fast technique if you reach a weight loss plateau. You can start by following my weekly diet plan here: 7-Day Grab & Go Keto/Paleo Diet Plan

Weight loss plateau

If for any reason your weight is stalling for more than 2-3 weeks and you have eliminated all the potential reasons. Make sure you check your keto ratio to eliminate the most obvious reasons for weight stalling such as too many carbs, inadequate amount of protein, fats or calories in your diet. You may want to try Intermittent Fasting (guide to IF is here).

After a "cheat day"

If you had a "cheat day" and would like to get back on track the next day. I would personally not use the fat fast for this situation but it is up to you. I would just keep eating healthy, low-carb foods from the day following a "cheat day" instead of giving my body such a calorie shock.

How Do I follow a Fat Fast? What Should I Eat?

Because most of your calories will come from fat, you have to make sure to include healthy fats such as MUFA, Omega 3s and saturated fats. You can follow this guide I have created for fats and oils to make the right choices.

The traditional Fat Fast guidelines advice is to eat 4-5 small meals a day, each about 200-250 kcal. This is totally up to you. If you prefer to have 1-2 regular meals like I do, it's perfectly fine. You can follow the fat fast for no more than 3-5 days.

Tips before you get started

  • Ideally, you should take a multivitamin to make up for the missing micronutrients on a fat fast.
  • Don't plan to do any extensive exercise on the days of the fat fast. This doesn't mean be inactive. You can always include light cardio (walking) or some strength training at home (squats, press-ups, etc.) but you should take it easy and avoid prolonged exercise. I personally didn't feel lack of energy or hunger and could easily incorporate some exercise every day (either 30-60 minutes walking or 20-30 minutes strength training).
  • Get an app to help you track your diet or make sure you track whatever you eat on a piece of paper. My iPad app has been designed specifically for low-carb, ketogenic & paleo diets. This way you can easily keep track of your macros and calorie intake, both of which are critical on a fat fast.

Many Small or Few Regular Meals? It's Up To You...

A traditional fat fast as defined by Dr Atkins in New Diet Revolution says you should be eating 4-5 small meals throughout the day, each of them containing 200-250 kcal. However, what I’ve learnt is that once you get keto-adapted, you don’t need to eat many small meals a day to stay sated. In fact, it may be easier for you to just eat 1-2 regular meals rather than many small meals, especially if you are used to Intermittent Fasting. Eating 1-2 large meals and having a long gap between meals (16-22 hours) is an example of Intermittent Fasting.

I rarely eat breakfast and often have my first meal round 1 pm. When I was doing the fat fast, I ate the same number of meals I’m used to (2 meals a day plus 1-2 cups of coffee with cream). I just increased the amount of fat to 80-90% and ate no more than 1200 kcal. In fact, unless you are hypoglycemic, you don’t need to eat too often. However, those of you who find it easier to have several small meals, you can try all sorts of fat bombs from my blog.

Keep in mind that eating just 1-2 meals instead of 5 small is my approach and it may not be suitable for everyone. I've tried the fat fast twice (with 4-5 meals and 1-2 meals a day) just to make sure all of these can be done and experienced the same results on both plans. However, I was struggling to follow the plan with several small meals. I always wanted to eat more than just a handful and my mind was thinking about food.

Below is an overview of foods you can include on your fasting days. Plus here is a complete list of suitable recipes that is updated regularly, making it easier and less boring for you to follow the fat fast!

"Small" Meals: Here is a selection of small meals you can have if you opt for 4-5 meals a day, each ~ 200-250 kcal. % Fat kcal
Easy 3-ingredient fat bombs (coconut oil, cocoa powder and stevia) - simply follow the recipe for my Chocolate Coconut Candies and only use the 3 ingredients listed above 92 65
Strawberry Cheesecake Fat Bombs 90 67
2 oz / 60g olives 96 82
Other Fat Bombs, all sorts of fat bombs from my blog (values per piece) 90-95 100-150
Coffee with 2 tbsp heavy whipping cream (or coconut milk) 95 109
Low-Carb Cappuccino (dairy-free) 90 113
2 oz / 60g cream cheese 86 138
1 oz / 30g extra dark chocolate (85% cocoa solids) 77 150
1 oz coconut butter (= blended coconut meat, not the same as coconut oil) 91 159
Home-made Coconut & Pecan Butter, 1 oz 79 151
1 oz / 30g almonds 78 163
Deviled eggs: 1 large hard-boiled egg, 1 tbsp mayo seasoned with salt and pepper 85 182
1 oz / 30g walnuts 87 185
2 tbsp full-fat cream cheese rolled in 1 oz of ham 79 186
1 oz almond butter 82 188
Smoked salmon & cream cheese rolls: 2 oz / 60g smoked salmon, 3 oz / 85g cream cheese 76 278
2 oz / 60g full-fat cheese such as brie 75 189
1 oz / 30g macadamia nuts 93 203
1 oz / 30g of macadamia nut butter with 1 oz / 30g celery stalk 92 209
2 tbsp coconut oil. Yes, if you can eat coconut oil just like this, spoon some right into your mouth! 100 234
3 large slices / 3 oz bacon 81 239
Buttered spinach: 1 cup spinach (5.5 oz / 156g) cooked in 2 tbsp cream and 1 tbsp butter seasoned with salt 85 256
Broccoli Cheese Pie 72 258
Spiced Coconut Chips 93 259
Easy Avocado Salad: 1/2 medium avocado (3.5 oz / 100g) mashed with 1 tbsp mayonnaise (home-made if possible) and seasoned with salt 94 272
Fish & mayo tacos: 2 oz / 60g mackerel, salmon or sardines (cooked or tinned) with 2 tbsp mayo served on 1-2 small lettuce leaves and seasoned with salt 84 292
1 oz / 30g roasted pecans in 1 tbsp ghee, butter or coconut oil with a pinch of salt 95 297
"Regular" Meals: Here is a selection of small meals you can have if you opt for 2-3 meals a day, each ~ 400-700 kcal. % Fat kcal
Scrambled eggs: 2 large scrambled eggs with 1 tbsp butter and 1 tbsp cream cheese 80 323
Cheese-Stuffed Portobello Mushrooms 76 334
Low-Carb Thin Crust White Pizza 73 352
Shamrock Eggs with Braised Spinach 75 360
Keto Mexican Rice 74 385
Egg & Celeriac Nests 74 397
Brussels Sprout and Bacon Hash 72 400
Poached eggs with Hollandaise: 2 poached eggs with one serving of Hollandaise sauce 83 417
Delicious & Simple Chocolate Mousse 88 435
Strawberry & Rhubarb Parfait 89 448
Grilled Halloumi With Strawberry & Cucumber Salsa 76 449
Keto Vegan "Zoodles" 86 449
Ultimate Keto Coffee 85 474
All Day Keto Breakfast 78 489
Keto Mexican Chocolate Shake 91 503
Ultimate Bacon Hash (without the orange juice) 80 521
Avocado & salmon salad: 2 oz / 60g smoked or cooked salmon with 2 oz / 60g cream cheese, 1 tbsp mayo and 1 tbsp finely chopped spring onion or chives on top of one avocado (7.1 oz / 200g) seasoned with salt 82 526
Paleo Greek Meatballs aka Soutzoukakia 72 539
BBQ Pork Ribs 71 586
Quick Tzatziki from 1/2 cup sour cream (4.1 oz / 120g), 3 oz / 85g grated cucumber, 1 clove mashed garlic, 1 tbsp lemon juice, 1 tbsp extra virgin olive oil, 1 tsp freshly chopped dill and salt 90 539
Shirataki noodles with bacon & cheese sauce: 1 packet, 7.1 oz / 200g shirataki noodles, drained and fried on 2 tbsp butter or coconut oil with 2 slices bacon (2 oz / 60 g), 2 tbsp heavy whipping cream, 1 oz / 30g grated cheddar cheese and salt) 87 604
Paleo Stuffed Avocado 78 633
Buttered spinach with salmon: 1/2 cup spinach (2.8 oz / 78g) cooked in 2 tbsp butter seasoned with salt and topped with a small salmon fillet (4.4 oz / 125g) cooked on 1 tablespoon of butter or coconut oil and topped with 2 tbsp of home-made pesto - Paleo Avocado Pesto or Red Pesto 79 639
Quick Beef Ragù with "Zoodles" 73 645
Avocado & mackerel salad: 2 oz / 60g mackerel with 2 oz / 60g cream cheese and 1 tbsp mayo on top of one avocado (7.1 oz / 200g) seasoned with salt 86 689
Pumpkin & Beef Sautée 73 762
Keto Omelet Wrap 78 765
Herbed Omelet 81 719
Salmon with Creamy Spinach & Hollandaise Sauce 81 813

3-Day Meal Plan (85-90% fat)

I've tried the fat fast twice and I'll be sharing my progress details as well as my meal plan (Update: you can find my experiment here). For now, here are two sample meal plans I created using the KetoDiet App. These meal plans are designed for those who prefer to eat 2-3 regular meals. The first one is higher in fat (85-90% calories from fat), while the second is lower in fat (75-80% calories from fat) and higher in protein (15-20% calories from protein). If you don't drink coffee, substitute it with tea or a few nuts of your choice.

Day 1

  • Coffee with 2 tbsp heavy whipping cream or coconut milk (94% fat, 112 kcal) and 2 oz / 60g of macadamia nuts (93% fat, 406 kcal)
  • Buttered Spinach with Salmon: 1/2 cup spinach (2.8 oz / 78g) cooked in 2 tbsp butter seasoned with salt and topped with a small salmon fillet (4.4 oz / 125g) cooked on 1 tablespoon of butter or coconut oil and topped with 2 tbsp of home-made pesto (Paleo Avocado Pesto or Red Pesto) (79% fat, 639 kcal)

Total daily values: Total carbs: 14.8 g, Fiber: 8.8 g, Net carbs: 6.1 g, Protein: 36.6 g, Fat: 113 g, Calories: 1182 kcal, Magnesium: 307 mg (77% RDA), Potassium: 1347 mg (67% EMR), 86% calories from fat

Day 2

  • Ultimate Keto Coffee (85% fat, 474 kcal)
  • Avocado & salmon salad: 2 oz / 60 g smoked or cooked salmon with 2 oz / 60g cream cheese, 1 tbsp homemade mayo and 1 tbsp finely chopped spring onion or chives on top of one avocado (7.1 oz / 200 g) seasoned with salt (82% fat, 526 kcal)

Total daily values: Total carbs: 23.7 g, Fiber: 14.8 g, Net carbs: 8.9 g, Protein: 33.8 g, Fat: 105 g, Calories: 1114 kcal, Magnesium: 284 mg (71% RDA), Potassium: 1562 mg (78% EMR), 85% calories from fat

Day 3

Total daily values: Total carbs: 38.3 g, Fiber: 20.5 g, Net carbs: 17.9 g, Protein: 15 g, Fat: 109 g, Calories: 1101 kcal, Magnesium: 198 mg (50% RDA), Potassium: 1924 mg (96% EMR), 88% calories from fat

KetoDiet App - the ultimate low-carb diet app

3-Day Meal Plan (75-80% fat)

Day 1

Total daily values: Total carbs: 30.4 g, Fiber: 17.7 g, Net carbs: 12.7 g, Protein: 45.6 g, Fat: 95.2 g, Calories: 1132 kcal, Magnesium: 259 mg (65% RDA), Potassium: 2368 mg (118% EMR), 79% calories from fat

Day 2

Total daily values: Total carbs: 34.8 g, Fiber: 17.9 g, Net carbs: 16.9 g, Protein: 54.5 g, Fat: 98 g, Calories: 1200 kcal, Magnesium: 228 mg (57% RDA), Potassium: 2608 mg (130% EMR), 76% calories from fat

Day 3

Total daily values: Total carbs: 20.7 g, Fiber: 7.1 g, Net carbs: 13.6 g, Protein: 58.6 g, Fat: 94.4 g, Calories: 1158 kcal, Magnesium: 249 mg (62% RDA), Potassium: 2195 mg (109% EMR), 75% calories from fat

Complete Guide to Fat Fast

Fat Fast FAQ

Is fat fast suitable for everyone?

As mentioned above, fat fast is suitable for breaking through a weight loss plateau and those who are already keto-adapted. If you attempt to do a fat fast without being used to a LCHF (low-carb, high-fat) diet, you will make your life difficult. Make sure you follow a low-carb diet for at least 4 weeks before you try a fat fast.

Keep in mind that a fat fast is quite extreme and if you have any medical conditions such as diabetes, you have to inform your doctor and only follow the fat fast under his medical supervision. It is very likely that with any dietary changes, your medication dose may need to be adjusted. This recommendation applies to all dietary changes, especially if you start following a low-carb diet that is very different to what most people have been used to (based on the Standard Dietary Guidelines).

If you are hypoglycemic, you will likely have to eat more small meals a day (traditional Atkins approach) and avoid going for long periods without eating.

Is it safe to follow fat fast for more than 5 days?

Although studies by Kekwick and Pawan and then by Benoit showed no negative side effects on a 10-day fat fast, they have proven to have many flaws and the results are therefore unreliable. The main reason you don't want to do fat fast for longer is the increasing risk of muscle mass and deficiencies during prolonged periods of drastic calorie restriction. It's better to be safe than sorry and for this reason, I'd personally follow the fat fast for up to 5 days, as originally recommended by Dr Atkins. Some resources say that fat fasting for longer (e.g. 10 days) is dangerous but I haven't found any supporting evidence to these claims.

What if I'm hungry?

Fat is calorie-dense and when you eat 1000-1200 kcal from fat, you'll realise it's not a lot of food. It's still better than doing a complete fast but you may feel hungry, at least during the first 1-2 days. If you are not keto-adapted, don't do the fat fast. You will feel hungry with no energy and most likely will develop symptoms of "keto-flu".

Drink loads of water, tea and some coffee and if you have to, avoid all sweeteners, including low-carb. Even low-carb / zero-carb sweeteners may trigger cravings in some people. If you are one of them, avoid using sweet fat bombs during this fast.

Most people find it easier to eat 4-5 smaller meals a day while others (including me) prefer to eat 1-2 regular meals. Make sure you don't exceed the 1200 kcal limit. When it comes to fat percentage per day, it's up to you. As mentioned above in the first part of this post, adding some protein seems to do no harm. Do not add more carbs. If you eat less than 80% fat, make sure it is compensated with protein, not carbs.

Do I gain all the weight back?

After you complete your fat fast, you should go back to your previous way of eating (low-carb, whole foods). Don't expect to keep all the weight off. Although you will probably gain some of the weight back, you should be able to keep a few pounds off. The weight gain doesn't necessarily mean you gain body fat. When you lose weight on a fat fast, part of it is because your digestive system gets "empty" and you also lose water.

If you follow a 3-day fat fast, you should lose 4-8 pounds and gain up to 40-50% back. If you follow a 5-day fat fast, the weight loss could be even larger, up to 6-10 pounds and again gaining up to 40-50% back. The fat loss depends on your current weight and body fat percentage. In general, people with more weight and higher body fat percentage lose more fat than those with just a few extra pounds.

Can I do fat fast without dairy?

Yes, you can. Use coconut milk / creamed coconut milk instead of cream and cheese and ghee, lard or coconut oil instead of butter. You can also use mayonnaise instead of cream cheese in some of the suggested recipes. Although I didn't follow a dairy-free fat fast, I was naturally avoiding too much dairy and included foods rich in micronutrients (avocado, nuts, eggs, spinach, etc.)

  1. Kekwick, A., and Pawan, L.S., "Calorie Intake in Relation to Body Weight Changes in the Obese", Lancet, 1956 and "Metabolic Study in Human Obesity with Isocaloric Diets High in Fat, Protein and Carbohydrate", Metabolism, 1957  

  2. Benoit, F.L. et al., "Changes in body Composition During Weight Reduction in Obesity: Balance Studies Comparing Effects of Fasting and a Ketogenic Diet", Annals of Internal Medicine, 1965 

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Martina Slajerova
Creator of

Martina Slajerova

I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight.

That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food.

About the Reviewer

This article has been reviewed by Franziska Spritzler, RD, CDE who is a qualified expert. At KetoDiet we work with a team of health professionals to ensure accurate and up-to-date information. You can find out more on the About us page.

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Comments (175)

I am very impressed with your website. I have been Keto for almost 4 years and the last 6 months have been tough. I needed to reset or restart and I am so glad I found you. I am going to try the Fat Fast for 3 days and I am excited. Thank you for sharing this information for free you have given me new hope. I will keep you updated.

I now regret that I stopped my Premium Service a couple of years ago. Your BLOG help me more than I realized. I'm basically starting over again & glad your Blog is still active.

Hi BJ, feel free to join our keto community, we are there to help in case you have any questions!

Is there a way to get your plan tailored to someone who eats only beef and pork?

Hi Elaine, I'm sure you can do that. In fact if you want to try a 3-day fat fast, pork belly would be the ideal option.

I just stopped by to see what Fat Fast ideas you had.  Wanted to tell you you did a stellar job with this particular post/article.  Well explained, useful information for those new to this concept and a lot of creative recipes in your list there.  Good job!

Thank you Peggy!

I can’t seem to get it right and I always fail at it!! I wish I could understand it and make substitutions for the stuff I don’t like! I don’t like avocados or salmon! I have a hard time fixing meals and stuff because I don’t know how to figure macros when I’m eating??

Hi Melissa, I can only imagine how overwhelming this must feel, especially if you are new to keto! No worries we are here to help! Here's a tool to help you find your ideal macros: KetoDiet Buddy - Easy Macro Calculator for the Ketogenic Diet
Here's all about our tracking app:
Here's pour Facebook support group:
I hope this helps!

I ve read your article many times and its very explanatory and helpful. Thank you!
In my personal case, I completed a 5-day fat fasting (eating only coconut oil) with great success, losing 4.2 kgr going from 70kgr to 65.8.
But now I am really struggling to keep the weight from coming back although I am still on keto.
Today I weighed and I am 68.5 and I was wondering, all this trouble to gain everything back?
Should I restrict my calories to 1200 like I did when I fat-fasted? Is there some other reason? What could I be doing wrong? (I havent cheated the least bit).
Kindly advise...

Hi Maria, that is very common I'm afraid. I wish it was easy and there was one thing that worked for all of us - I can only imagine how frustrating it must be! Have you seen this post? How To Low Carb: 15+ Common Weight Loss Mistakes I hope this answers some of your questions! Other than that, you can join our support group on Facebook - our admins are happy to help!

hi, thanks for sharing all this information!!!!
my question is... if I want to use your guide of meal options (just to have an idea)  should I pick a few options that add up to 1000 cal /day? is it ok to mix and match options from the 4-5 small meals and the 2-3 regular meals as long as the calorie intake is around 1000?
thank you!!

Absolutely, you can do either! It doesn't matter how many meals you have but I personally find it easier to stick with 2-3 main meals (even if composed of smaller snacks).

Hi there!
Can you eat chia pudding on a fat fast (coconut milk + chia seeds)?

This sounds like a good high-fat option to me! 😊

Hi Martina
I am really enjoying your blog. Keep up the good work.

Thank you Thomas!

Hi there
Really enjoy your recipes which are a regular eat in my household.
Is your Fat Fast a Fast Mimicking Diet? I've been scouring the internet for how to make a whole foods/keto/primal sort of FMD instead of a pre-packaged and processed version that one could buy.

Thank you Aleesha! A fat fast very low in carbs, calories and protein and in many ways it is similar to a regular fast (eg producing ketones) but I would say it's not so similar to the FMD which is mostly carb based (to be avoided). The problem with a carb based low-calorie diet is that you will constantly feel hungry (blood sugar spikes). This video from Dr. Berg explains FMD in detail:

P.S.  I forgot to ask if Buttered Coffee / Tea is acceptable on your fast?
Thank you again 😊

It is suitable for fat fasting - the more controversial topic is whether it is suitable for intermittent fasting because it's over 50 kcal.

Hello Martina,  Thank you for all the info you provide.  I am on Atkins Induction with a little Keto thrown in when I can't find the answer in Atkins.   I would like to know if I can substitute Tuna,  Haddock or Halibut for the Salmon.  I am not partial to it but I do like smoked Salmon / Lox.
Thank you so much for taking the time to answer.
Best Regards.

Hi Leslie, you can swap salmon for fatty fish like mackerel, herring or sardines. If you use lean fish then you will need to add some healthy fats (olive oil or homemade mayo). I hope this helps!

I'm new (2 weeks) to the keto diet and quite like it. However, my wife and kids are not and we eat all meals together. And we're vegetarians, so I can't just eat meat. I don't do cow's milk, but butter (yes), so it's really hard to avoid carb splurges (millet salad? sounds healthy).
Any tips?

Hi Kelly, this post may help: Vegetarian Diet and Keto - Can These Two Work Together?

How do you get off of keto after you’ve lost the amount of weight you wanted to lose and you want to get back to a normal diet without gaining all of the weight back?

Hi Alexa, I never "got off" keto or low-carb. I believe that t only way to make this work is not to use it as a short term solution but rather adopt a healthy low-carb lifestyle.

Excellent information. Thank you. I'll be doing a fat fast this weekend. after 6 weeks I'm down 33 lbs but stalled. I eat 1900-2000 calories, intermittently fast everyday, and eat less than 15 carbs. Hopefully this will break the plateau.

I would love to understand this better.  I have about 40 lbs to lose.  I am currently on day 5 of the keto diet...but I am unfamiliar with it and I actually, according to this post, am doing this as what you called the fat fast way.  I have lost 5 lbs.  I am not having any issues w straying or being weak.  I do not crave.  It does feel weird to eat fat bombs and look at my daily break down and see fat so much higher than protiens.  I am trying to keep it at a 1000 cal a day.  As you said, this is next to impossible to get the 70% fat Im trying to get in a day. (Do I need to increase calories to accommodate up to 80% fat, to make what im doing an actual FAt Fast?) So, I am unsure, after 10 days of this, should i just, increase my protiens, or what, to come off the fat fast?(If what im doing is actually fat fasting)  WHat is normal that I should go back to?  I will not go back to carbs at all, if i can help it.  How do I break up the fat fast to stay healthy, but still accomplish my goal of 40 lbs?  I guess, im looking for numbers or percentages that would be o.k to go back to, if I plan on cycling this in and out of my diet.  Help?
*confused but determined

Hi, I really like your website. Sorry this is a little long - I am not sure the Kcal and fat% calculations are totally accurate though. One you mention is:
“Smoked salmon & cream cheese rolls: 2 oz / 60g smoked salmon, 3 oz / 85g cream cheese   75%fat   189Kcal”
I wouldn't normally care - but I am in love with smoked salmon and cream cheese (I also add chia seeds, pepper, garlic, and some red onion- so its kinda like an everything bagel).
I ran the calculations... for 85g cream cheese and alternatively 85g cream cheese with 60g smoked salmon - I got all calorie info off google search. Apology - formatting isn't perfect. Feel free to email me for real formatting.
So just the cream cheese would be 261 Kcal and 89%fat - so its already over your listed 189Kcal.
Should be 361 Kcal and 78% - but 75% is close enough...
Im not sure but those calculations are wrong - i just didn't want any confusion for people new to running macros.  
Another awesome Recipe is 4 slices of salami, 2 oz cream cheese, and 4 olives. =)
Thanks and keep posting

Hello, thank you for spotting that, there was indeed a typo! There was a difference now that I recalculated it in the app. I must have used a different cream cheese (perhaps accidentally lower fat). There is still a difference but in this case it can be explained as inaccuracies on google. I explained more about what we do in our app to prevent inaccuracies in this post: Barcode Scanning and Food Database in the KetoDiet App
I hope this helps!

Hi! I've tried the fat fast lots of time. Wonder though if having dark chocolate is still ok. Will it be as drastic as in its original Keckwick edition? That'll be a nice alternative, I've never tried before.

Yes, you can have it as a treat - a small amount of dark chocolate is perfectly keto (ideally 85% or more cocoa)!

I am shocked to see that the fat "fast" is still popular and promoted!
The only reason why you will lose weight on this "fast" is the caloric deficit you are imposing by eating almost all your calories in fat but at 1000-1200 calories a day. It needs to be noted that if you ARE eating 1000 calories of fat your body will burn that first before it goes to burn your stored body fat. The protein macro on this diet is way too low to sustain your muscle mass so that you will lose muscle weight as well instead of fat. Please do a little more research before attempting this silly "diet". If you are interested in FAT loss try the Protein Sparing Modified Fast. At least there, you will actually lose FAT and keep it off!

Dear Karoline, have you actually read this post? Please, do a little more reading before leaving "silly" comments. Your research when it comes to PSMF is somewhat limited if you think that it guarantees long-term weight loss.

Martina, your blog was very well written and informative. Don't let internet trolls, who aren't worthy of a response, make you react defensively. You wrote a great article, appreciated by many, and this rude poster does not deserve a response or emotional reaction. Just keep doing your thing and ignore the haters. They make themselves look foolish enough…...

Thank you Diana, I appreciate that!

I have been following this diet to the point. I am on my third day doing the fat fast. I have not lost any weight but all the contrary, I've gained 2.2 pounds. I am really disappointed because I was certain that this would work for me.

Hi Sandra, 2.2 pounds is too little to tell whether you gained weight, it may be just a fluctuation (common especially for women). I recommend you read this post as it may explain why that happened: How To Low Carb: 15+ Common Weight Loss Mistakes

Thank you for your awesome blog! It is very hard to get correct info on fat fasts Nd you nailed it!
I am on day 5 fat fast today.
Started at 1;6.4 , day 4 am I was -142.8, same as day 3-142.8, going on day 5 and hoping to see some movement. But so far-3.6 lb lighter.
After reading Salerno's silver cloud diet book , I am seriously considering to continue the fat fast until I get UNDER -40- 1:&/:9 and then go back to keto that I have been following for the past 3 years.
Any experience or data on longer fat fasts?
My " ideal weight " is 131-133 range , I am active - but I don't lose on reg. Keto. I maintain at -1400 cal , under 20 carbs with 60 /65 grams of protein per day,

Hi I came upon this recipe and when I added up the calories and fat etc., it looks to have 250 calories in 1 slice (10 slice pie) & about 89% fat could we use this as one of the meals?

I recently decided to try the Keto lifestyle and in doing my research, I discovered your site. It has been SO helpful! I have lived most of my 46 years on sugar, carbs and caffeine so I decided to try a bit of a different approach to switching my diet. I started a 3 day fat fast and incorporated KetoCaNa into it. I only do a total of one scoop per day divided into 2 doses; morning and late afternoon. I can honestly say that thanks to your recipes, I have not struggled. I get my caffeine from black tea as I HATE coffee and obviously can no longer have my morning Pepsi. When I crave carbs (mainly my Pepsi and fruit), I drink 24 oz of water and find that the craving goes away. I think the exodgenous ketone supplement and the great taste of your recipes are what have made the last two days such a success. Thank you!

Hello and thanks for posting all of this wonderful info. I have been following you for a while and everything is just so helpful. Last night I completed 3 days of this fast and down 4.4 pounds and 2 inches gone from my waste. I was scared I would not even make 1 day of this fast because between Thanksgiving and the New Year, I fell off my keto woe and totally developed all of those horrible sugar cravings again! But I was really surprised at how well I was doing. I wasn't hungry until right before the last meal each day.
Today is day 4 and kind of difficult though. Maybe because I'm close to the finish line lol. But I will stick with tomorrow because what's one more day? I just want to encourage people who are skeptical that this fast does work. I'm a bit hungry today but I think it's mainly mental, to be honest. One great thing about this is I am no longer hungry for bad stuff, and I am losing weight, and I will be back to doing keto the right way again and getting in shape!

Thanks for such a wonderful blog!! I have been following you for a while and it helped me a lot.
I have a question for you though.
I did try "Fat fast" and it worked for me (in fact,I'm on the 5th day and I 've lost 4 pounds)
So I'm wondering if it's OK that I will go back to my normal eating and go on "Fat fast" again in 2 weeks?Will there be any harm?

Thank you for your kind words, Nan! I can't be absolutely certain because I'm not a doctor and can't evaluate your health but unless you have any health condition, it shouldn't be an issue. It may be better to take a multivitamin, especially if you do this for 5 days.

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