Insanity gives me adrenal fatigue, why?

succubaeangel

This is my second time attempting Insanity. Last time, a year ago, I wasn't strong enough to follow the schedule so I did it with one day off in between. After week 4, I was exhausted, couldn't sleep, couldn't think straight. I was tired all the time and hungry. I lost about 6 kg which was the point but I had palpitations, heart pain and felt like ****. The sings seemed similiar to those of adrenal fatigue and too much cortisol.

Now, after some time of doing other stuff (lifting and jumping rope for cardio), I need to lose some weight. I'm in week 2 of Insanity and now I'm strong enough to follow the schedule but ...now I have the same symptoms that I had in week 4 last time. I decided to stop of course, but I'm still wondering as to why this happens to me. My health is checked so it's not that.

Is it because I'm still not strong enough for plyometrics? Or is the program just bull and is not sustainable in the long run?