I've done Insanity. Not to lose weight (I'm currently 18% bodyfat) but for a fun challenge with my OH. It was tough and I was browsing Youtube to see what P90X was like when I stumbled across this chap:
There are many truly inspiring videos on youtube (related to P90X) but AIBU that anyone that is able bodied enough to exercise could fail to be inspired by this; fat gene or not.
What an amazing guy.