I watched every single episode of My 600 lb Life. Everyone is given a diet plan. It was at least 20+ pages thick, and in one episode (forgot which one) there was a close up shot of the plan. I paused to read it and it was very detailed and easy to understand.  James K even spent a month in hospital after arriving at Houston, where he ate hospital food which strictly follows the plan. There is no way he doesn't know what to eat.