Also, for those wondering why I care - I’m interested in pursuing a career that requires me being a certain weight, and I’m fascinated with trying a water fast to help get me there. No, I’m not expecting it to be a magic bullet to easily get me there, I know it will be difficult. I care about the strength loss because I’ve weight-lifted for many years and I’m just curious what to expect, I’d like to know if I should expect to lose significant muscle too.
I’ve been researching this myself and have only found a few conflicting testimonies. I’ll update this myself once I complete a fast with my experience.
If you are talking about losing muscle mass, everything I’ve read suggests that when you fast, your body increases certain hormones to maintain muscle mass and you don’t lose it very easily. I do 3-4 day water-only fasts and when I get back to the gym, I’m still at the same weight settings and reps that I was before I fasted. My impression is that you would probably have to do a pretty long-term fast to lose mass, maybe around the 2 week mark or more.
I will say don’t go back to the gym right away. Give yourself a couple of days of eating before trying it. I tried to go to the gym 12 hours after I started eating again and I didn’t really have enough energy, so I have learned from that.
From reading various studies and personal experience, it seems like a 3 day water fast is sort of the sweet spot for optimized fasting, you can still get advantages from the longer fasts, but a 3 day doesn’t seem to significantly affect any of my strength metrics.
If you doing it purely for weight loss, plan on gaining back about 1/3 of the weight you lose during the fast. It might be different for you but that’s been about my average a week after refeed.
I don’t lose a meaningful amount of strength, but I definitively feel more fatigued and can get a bit light-headed (probably due to lower blood pressure).
> I’ve been researching this myself and have only found a few conflicting testimonies. I’ll update this myself once I complete a fast with my experience.
The problem is that it’s not that anyone is wrong or lying, but more so that there are too many variables that can influence this and make different people have very different experience. Mineral supplementation, current weight, experience with aerobic and anaerobic exercises, level of exercise that you’re doing, probably a bunch of other factors that I’m unaware of.
When it comes to fasting I think it’s interesting to read experiences for the sake of understanding what to expect, what could go wrong and how to address that, but ultimately I think it’s important to keep in mind that you’re a different person and potentially fasting under very different conditions.
Depends on what you mean by “strength”. If you’re talking about maximal, one rep strength, then yes - but likely depends on specific lift and the training leading up to it and what training level you’re at in general. My 1RM on the overhead press will dip about 10-15% shortly after not just fasting, but any kind of dieting, missing sleep, or extended absence from high intensity training - and sometimes for no apparent reason whatsoever, just bad days. Top end strength has to be religiously maintained, and a big part of it is neurological, not just muscle.
tl;dr You can’t serve two masters.