Low Intensity Steady State exercise like jogging is great for fat burning - but needs a longer duration. It also doesn't need to be done fasted but if you're doing 3 sessions at half an hour a week, frankly it's not a lot.

If you're doing it with a huge calorie deficit you'll burn muscle - no way around it. I mean IF is supposed to increase metabolism and reduce calories right? Make sure you calculate your TDEE and match your calorie intake so that you can lose weight safely

Also, I'm not a fitness guru.