Not only fruits and veggies although there are such detox programs Eating plenty of fruits and vegetables, not eating junk (fast food, fried foods, sugary foods), drinking plenty of water, etc is the best way to promote self cleansing of the body.
I'd even go further and limit certain things like dairy, meat and wheat products.
You can't out-exercise poor eating habits.
I was wondering about the Jillian Michaels cleanse, too. I had tried one in the past from GNC, but it was full of garlic and it was disgusting. Would like to hear about any results (good or bad) from this specific product.