Ketosis for weight loss, Fasting, Diet, Protein

Answered on June 27, 2016
Created May 03, 2013 at 3:24 AM


Question 1: IF you fast while in Ketosis will you lose body fat (if you have body fat, which I do) (i.e. will your body turn to this for energy, even when you aren't eating fat)

Question 2: I understand fat cannot give you all the nutrients you need to survive, is a Multivitamin good enough to reduce the amount of muscle broken down during a fast?

Question 3: Will using my muscles (light weight training) reduce the body's consumption of them for energy deficits?

Question 4: Will drinking a small amount of protein shake every two days reduce the need for the body to turn to muscle for deficits?

To give some more insight on my situation:

I am currently fasting for weight loss. When I say fast I mean: Centrum multivitamin, lots of water, black tea/coffee (not much, maybe 2 cups/day), some fresh lemon juice + cayenne pepper in water, and on the second day of my fast one small serve of protein shake with water in two serves throughout the day)

I've been fasting for about 70 hours now, I am in ketosis +++ (just checked, so yesterdays protein shake did not push me out of ketosis....)

Starting BMI 25.3 (estimated - about 75kg) Current BMI 24 (about 71kg) Goal BMI 21.9 (about 65kg so a total loss of 10kg hoped for)

Okay so fasting - I was planning on fasting every other day (Alternate Fast Diet) however now I wish to fast as long as I can sensibly to lose as much as I can quickly - espeically in ketosis I'm hoping to burn stubborn belly, back, thigh and arm fat.

After losing this fat I was going to wean out of the fast slowly over several days (diluted juice, then vegetable soup, then lean meat, etc.) in order to adapt my metabolism and not gain what I'd lost. I was also going to continue with the Alternate day fast diet after I had finished my fast

Thank you so much for reading all this, I really appreicate the time you guys take to give your advice to strangers for free.

  • 5232b6325600523566068f41d18f2640

    asked by

  • Views
  • Last Activity
    1203D AGO
Frontpage book

Get FREE instant access to our Paleo For Beginners Guide & 15 FREE Recipes!

1 Answers


on June 27, 2016
at 10:23 PM


I've been attempting the same as you for some time now, about two months. So I don't have long term experience but I can share what I've learned from experience so far and from what I've read on the subject.

To answer your first question: yes, your body will definitely turn to fat stores while on a (water?) fast. If you are already in ketosis, it will be much easier entering the fast since you won't go through carb withdrawal. You will lose a ton of weight at the beginning. The first time I fasted I lost 1kg on the first day, then 0.7kg and the day after that 0.5kg (at the time I weighed 68kg, when I attempted the first water fast). Note that I had been fasting intermittently for about two weeks before the fast, and for about a month I had been eating a preferentially ketogenic diet. What you lose is water, fat and muscle at the beginning of a fast. I suppose the more keto-adapted you are the less muscle you will lose, but I've read that no matter how long a water fast is you will inevitably lose muscle, even though you go into "muscle sparing" during ketosis, but it's practically negligible. Like, if I lost 10kg of fat I wouldn't mind at all losing 1kg of muscle, for example, because I would build it back after. Also, just a side note, when you fast the glycogen is pulled from your muscles, and that contributes to the large amount of weight you lose, because when your glycogen stores are replenished (like after you eat carbs after a fast), they also pull water into them. I've come off a fast and eaten carbs, and the next day I weighed an extra 2kg. BUT, I have come off another fast and kept a ketogenic diet and STILL kept losing. I would lose less but lose nonetheless. Also know that I fast intermittently. I believe this contributes greatly to maintaining my weight loss. For example, now I'm only eating once every 24 hours. So from experience it's advisable to not dive into carbs after a fast.

To answer questions 2 and 3: taking multivitamins I believe is a personal prerogative. It all depends on why you're fasting and what your priorities are. In your case it's fat loss. I suppose you could take a multivitamin if you wanted to but since you're not on an extremely restrictive diet, it's not extremely necessary. I also take multivitamins but when I fast I prefer to not ingest anything at all besides water, because a pill needs to be digested and when I'm fasting I want to give my digestive system a complete rest.
I'll abstain from answering question number 4 because there's contradictory information about that, but I'll just go back to my answer for question 1 about muscle loss. To simplify, you have to establish a priority and stick to that. My priority for example is fat loss. I can't lose fat and build muscle at the same time (unless I carb cycle, but that just complicates things further) so I prioritized fat loss. I know I will lose muscle. I believe I have lost some strength because the last time I weight trained I couldn't do half of what I did a month ago. But that's fine. I need to lose the fat first and then I will embark on a muscle building journey. Because I keep it simple.
I hope I was able to help you. I know my answer is long but I like to be specific and objective.

Just one more piece of info: you said you fast on water, coffee, tea and vitamins but you have a protein shake every other day. For me, the day you ingest the protein shake is not considered a fast since your supplying your body with calories. From what I gather, it's not enough to kick you out of ketosis, and that's good but it's gone from being a fast to being a highly calorie restrictive diet. The benefits of fasting outweigh those of a calorie restricted diet.
If you want my personal opinion, I can tell you what has been working for me. It's very similar to what you're doing so it won't be too difficult. It's all about simplifying. Cut out the protein supplement, maybe even the vitamins (at least in the beginning of your weight loss venture, you can reintroduce them once you're closer to your goal weight). Fast for as long as you can, like as a reset, for about a week or three to four days (which is how far I got). Then fast intermittently (like, eat only once a day), and KEEP A KETOGENIC DIET. That's my key.

Answer Question

Get FREE instant access to our
Paleo For Beginners Guide & 15 FREE Recipes!