My husband did it. For him, he had MUCH better results when he followed the diet plan too. He only did the diet plan for a couple weeks, but he showed more improvement in those 2 weeks than the other 2.5 months. It's basically a LOT of lean protein, lots of veggies, a little fruit and dairy, and almost no carbs.
Also, I highly recommend keeping the yoga. I thought it was silly at first but I was really impressed with how much it helped DH.