I recently did their 24 day challenge and my immediate advice is: DO NOT DO IT. Not only are the Spark and Meal Replacement shakes laden with SUCRALOSE they are insanely sweet and not filling at all.
Also yes, they want you to eat a diet that is LOW FAT, LOW CARB, and HIGH VEGGIES AND FRUITS. Which is pretty much the opposite of Eat for Heat and everything that Matt stands for. They also want you to drink excessive amounts of water, to the point I was peeing every 20-30 minutes. I actually felt better on their cleanse than the second MAX phase. The vitamins did nothing for me, and their stupid Thermo Plus product gave me migraines. I stopped at day 21 and immediately started feeling better.
I’d be happy to answer any specific questions. But please, save yourself the money and harm to your body, and don’t do it.