I have fasted 3 and 7 days few time and now my plan is to do a 40 day water fast.Would it cause massive issues if I do 1 hour gym and 30 minutes running if I am fasting for a long term?
7 to 40 is a big jump. I’d take it week by week and listen to your body.
Also how often will you be doing this 90 minute routine? Ideally you’d want to be resting as much as possible.
But if you decide to workout to this extent make sure you’re getting sufficient electrolytes