No, the Plastic Bag Diet doesn't involve eating plastic for weight loss (although, horrifically, we are all eating plastic these days.) This is about helping people give up plastic bags.
The Story of Stuff (organization) is working on another feature film on plastics. But here's a segment. The main points are that the solution to plastic pollution is prevention, and that the way to help people give up plastic bags is to hand them an alternative. One thing that shocked me is how plastics are now buried deep into riparian soils, so they can't be recovered.
You can watch the short video here.