Prior to Insanity, I worked out about 4-5 times a week at the gym (mix of cardio/pilates/yoga), but saw the intensity of my cardio workouts decline as my life (aka work) got busy, definitely wasn't as lean as I wanted to be (and fat to mass ratio was starting to increase).
When I first tried insanity at one of my friend's place, I was totally out of breathe which surprised me since I thought I was in pretty decent shape. So after two workouts, I was sold, I needed to get it - i thought this would be a good 60 day program to do to change up my gym routine.
I'm on day 27 - and definitely have seen results (I'm leaner and more toned). I'll be honest, I don't follow the diet consistently or track my calories but have paid more attention to my diet and do allow for a couple cheat nights a week :) My goal is not for massive weight loss - I started at 127 lbs i'm down 5 lbs but am definitely toner. I've loss inches around my waist and my chest and am definitely stronger.
Definitely recommend this if you're looking for weight loss/toning!