I lost zero noticeable lean muscle mass on my 60 day fast, at least no more than I would have sitting on the couch doing nothing.
There's just not a metabolic pathway for breaking down muscle/organ tissue for energy when you have adequate fat stores. We would have died off as a species a long time ago if that were the case.
In the grand scheme of things, if you have the body fat, 7 days is nothing for a fast.
Edit: To those asking, yes. I fasted for 60 days, water and electrolytes, no calories.
Once-ish a week there was Light lifting, think moving a whole trees worth of firewood or a light day on a family farm.
Quite frequently I hit over 10k steps/day on my step tracker, sometimes double that. I live in the middle of a major city and walk everywhere, and this was before work from home.
If you’re looking for exercise/fasting advice check out my fat per unit time post elsewhere in this thread.
There's just not a metabolic pathway for breaking down muscle/organ tissue for energy when you have adequate fat stores. We would have died off as a species a long time ago if that were the case.
In the grand scheme of things, if you have the body fat, 7 days is nothing for a fast.
Edit: To those asking, yes. I fasted for 60 days, water and electrolytes, no calories.