I did the workout sessions of the original Body for Life a few years ago. It wasn't the "for women" version which came later. I made the commitment and did it for 12 straight weeks.
Thing is I am an Atkins person. Firmly and truly believe in low carb as the way to lose weight. So I tried to do BFL with Atkins as my diet part. It didn't work for me very well. Not enough energy with true Atkins to be able to work out that hard. So I wound up not really on a diet during that time.
I did lose a dress size during the 12 weeks. Got down to a size 16 from about 18 or 20s. Got to my lowest weight ever the week I WAS able to do Atkins induction and also BFL. But I couldn't sustain the exercise level at 20 grams of carbs a day. Too exhausting.
So during the 12 weeks I didn't lose any weight that I kept off. I did gain a lot of muscle, and I did lose a clothing size. Looked pretty good when I was done. At first though I found I was gaining weight, not losing it.
From calculations I did using the fat measuring calipers, I determined that althogh no pounds came off, I decided that I had lost about 15 pounds worth of fat, and gained the same amount in muscle mass. That was a guess though based on math and fat caliper pinch tests that could have been less than completely accurate.
Body for Life is a good program if you can make the commitment and stick to it. It isn't for sissy's. 12 weeks, 6 days a week working out. It is a serious commitment. I'm not convinced though that his type of aerobics is good for a person. I know I really overdid it when it came to the aerobics part of it all. Aerobics in order to really burn fat need to be done in a certain "zone". Work at it too hard and you wind up not burning fat so much as burning fuel that you eat. I worked at it WAY too hard, and I think it slowed my metabolism as a result.
If I did it again I would definitely do that part differently.