In general, I’ve read that it’s not advisable to perform strenuous exercises while fasting because the exercise may be too intense (even dangerous) to perform if you don’t have the energy to execute movements with proper form. And you may not have enough nutrients to replenish your muscles after exercise.
But I’ve also read that you get a greater body composition and lipid profile than with fasting or exercise alone.
So, prolonged fasting and HIIT or weightlifting: can they go together?
From my research I found that low intensity cardio is recommended while fasting. However weight training or any exercise for hypertrophy is not recommended as you won’t have the protein available for your muscles to regrow and it will encourage your body to break down more muscle fiber rather than fats.
I do 40-60 minutes of HIIT 24-36 hours into my 3-5 day fasts and always feel amazing after. I have plenty of energy until I hit the 72 hour mark and then I have slightly less energy but more mental clarity. I’ve noticed that my muscles are less sore when I do fasted HIIT. I do daily walks during my lunch hour the rest of the time.
I do 72 hour water fasts weekly.
Day 1 I do a 25 min HIIT interval training and an abb workout. Day 2 I do a full body workout with supersets and triple sets and 30 min of 15% incline threadmill walk.Day 3 I do a 30 min 15% incline threadmill walk plus ab workout.
In between I also travel by bicycle everywhere I go and in the past I had a 90 min bike far including 2 hour salsa dance class on day 1 together with my HIIT interval training.
I did not lose muscle and my body composition increased more than by fasting alone.
Yes they can go together but seperate your HIIT workout from your weightlifting workout.