i lift 5 times a week, most of the time towards the end of my 18 hour fasting window. I’ve heard people say i wont build muscle that way and ive heard the opposite argument.
At the end of the day here is what i have found: your energy levels will most likely be lower than if you had food in your system. But over time that effect lessened. Took about 8 months for me to feel the same working out fasted vs fed. Your appetite will also increase after you workout so be prepared to be a bit hungrier during your fasting window. Overall though ive gained a fair bit of muscle, certainly havent lost any.
Unless youre training to be a professional athlete I really don’t think it matters very much.
I workout 5 days a week at the gym and swim 3 times a week and all within my fasting window. Prior to starting IF, I was already working out on an empty stomach. I would then have breakfast, but once I started IF, I was able to hold on until my eating window (which is around 12 to 1.30 pm). In an ideal world, I would love to be able to do my workout and then break my fast afterwards, but it doesn’t really fit my schedule.
On the rare moments when I can workout in my eating window, I do find that I have a bit more energy, but I have more or less gotten used to it. I have been doing IF now for around 3 years and have been working out more or less around the same period. I think you just need to make sure you are getting sufficient protein / calories within your eating window and getting plenty of rest. Hope this helps!