Your weight loss on 24-36 hour fasts


For those of you who fast for 24 to 36 hours at a time, do you lose weight? I’m asking generally about your impression as to weight loss, unless you collect your data in a way that makes a solid correlation possible.

Do you see a loss on the scale the day after you end your fast?

I do realize there are other things going on and benefits beyond weight loss. Perhaps my question can’t be answered simply either but am curious of the people trying to lose weight if they actually see the scale change and feel rewarded in that way.

(Tyler) #2

I be done one 48 hour fast mainly to see if I could do it. As far as weight goes I didn’t weigh myself as I try to stay away from that more than a couple of times a month. I can definitely see a difference in how my clothes fit when I do a 24 hour fast which I do one day per week now.

(Katie) #3

I do a 24 hour fast every day. Often going to 48 because I am just not hungry. I only weigh myself on Friday. I have seen a steady ~2lb loss per week.

(Karen) #4

When I do 36 hour alternate day fasts I lose ~0.5 - 1 pound every other day. I personally find it hard to stay with this though. And when I go off they come back

(Doug) #5

When fasting, we lose about half a pound of fat per day, with really big people perhaps being able to lose a little more. The fluctuations in the scale readings due to water loss or gain, electrolytes (salts), hormonal issues, etc., can completely swamp that half a pound per day, for fasts of only a day or two.

Over the long term, the fat loss will show up, but day-to-day readings are almost meaningless, as far as fat loss.


This is what I’m seeing though I’ve only fasted three times, each between 24-30 hours.

My weight has been the same from the day I start my fast to the day after I break my fast. I’m not overdoing it afterwards, usually having something small like a fried egg. The week’s rate of weight loss doesn’t seem to differ with a fast vs without a fast, based on my own data thus far, so from a weight loss perspective, it may not be something I should expect.

I’m in my fourth fast right now at about 26 hours so far. I may do 40 hours and see if that makes a difference. I’m likely fat adapted as I’ve been at this for 3 months with one “cheat” quite a while ago.


Thanks for the reply. As much as I would like to see a pound dropped the day after a fast, I realize there are so many variables that it’s unrealistic. Perhaps as I gather more data over time, I will continue to do my own n=1 comparisons of a week’s loss with a fast and a week’s loss without a fast.

(Doug) #8

:slightly_smiling_face: :+1: Yes - even if we keep our electrolyte levels the same (which is hard to do if not eating, versus eating), and if nothing changes hormonally, it might still just be a difference in hydration, i.e. we become slightly dehydrated or haven’t gone to the bathroom yet. 8 ounces of water - just a cup - could completely mask a half pound fat loss, or make it look like it’s an entire pound.

(May the blessing of bacon be always with you) #10

Welcome to the forums!

Fasting is not a requirement for a ketogenic diet, so if you don’t enjoy fasting, don’t do it.

Not only that, but we advise beginners not to fast at all, and only start to think about fasting once they are keto-adapted and find themselves forgetting to eat a meal. At that point, fasting might (or might not) be more comfortable, and you could experiment with it. But if you still don’t like it, then there is no need to do it.

(Robin) #12

Since you give no details like what you eat, for how long, how much weight you have to lose, age, current weight, health issues…. There is no way to respond to your situation.

As you see on this forum, it is absolutely possible to lose weight on this diet. If you want to figure this out, we’re glad to help but need way more info.