Today is day 1 of my water fast. I know that I shouldn’t do any weightlifting during this time, because I wouldn’t be able to repair the muscles I’ve worked. However, I’ve heard of others walking or biking for the calorie-burning advantage. But I’ve also read that the amount of calories burned via exercise during this time is negligible compared to the vast calorie deficit of water fasting, so don’t worry with it.
Any thoughts?
Hi, I was thinking about this too. I think I’m going to train at the beginning (like day 1 would be fine as you still have reserves from eating the day before) but maybe stop later on in the fast if I feel too tired. I guess listen to your body and see how it goes?
I mean, if your body is not busy digesting food, I imagine it has time to repair your muscles 
Your body can’t repair muscles on solely a water fast. It has to have protein for muscle repair, which is why I’m limited to aerobic, calorie-burning exercises only. No weight-lifting or you’d just be flogging your muscles to death.
I actually like to lift weights when in a fasted state or during extended fasts. Your muscle building hormones go way up during extended fast to preserve it. But there have been times I felt light headed. Just remember to stop when your body says stop. You are doing a lot on the cellular level when fasting so don’t feel bad about yourself if you take a break from exercise or exercising at the level you are used to with a full belly. Check out videos/lectures from Dr. Pradip Jamnadas–inspiring what the body is capable of during a fast.
Your body doesn’t repair muscle with hormones. It only uses protein to repair muscles. That’s nutrition 101. When you exercise a muscle, you’re tearing it down microscopically. Then, when you rest and ingest protein afterward, your body adds back just a little more muscle than before. That’s how a person gains muscle mass. That extra muscle that’s added is in the form of animal protein - not hormones. You shouldn’t be lifting weights on a water-only fast. If you want to burn calories, feel free to do that all day long, either walking, biking, or whatever. Just no weightlifting.
Exercise however you enjoy exercising during a fast.
Be kind to those around you who opt for different kinds of exercise and fasting methods.
Do your research and don’t talk down to people. No one knows everything, and there isn’t one end all be all way to exercise/fast and combine them for success.
“Exercising during intermittent fasting is a healthy way for you to burn more fat and build muscle. As you fast, your body produces more human growth hormone (HGH) and testosterone while battling insulin resistance. Together, this recipe helps you build more muscle, recover faster, and maintain your gains.”