My parents did it years ago.
It seems like something anyone could do... if they can stay committed to it. However, I think it's a waste of time and money. First, you pay for membership. Then you pay extra for their food.
It's like saying, "You want to lose weight? Pay us and buy our food." Sounds kinda like Amway and Quixtar where you pay for membership and then spend over $200 a month a month in order to get $2 back at the end of each month.