Now that I have watched all four parts of HBO's documentary, I would recommend watching the last segment. The main reason: It's mostly about food. 

As I have stated before: We do not have an obesity epidemic. We have a food crisis.

Here are just a few observations about the documentary.

1. There's a heavy concentration about eating fruits and vegetables. Everyone already knows to do that. Here's the real problem that is not addressed: How do you prepare and cook fruits and vegetables into delicious meals? Ironically, it is not difficult. Here are two simple examples - a fruit smoothie and an amazing veggie dish.
2. Throughout the documentary they stress community involvement, however, there's no serious attempt at a social networking component. For example, a reason to join an ongoing Facebook community or petitions at Change.org for better school lunches, elimination of food deserts, and more. 
3. The documentary obsessed about diabetes, however, there was rarely a mention of heart disease.
4. On several occasions, they mentioned that children might die at a younger age than their parents (paraphrasing). I have a sneaking suspicion that over the next 50+ years, medical technology will keep us alive for a long time. It's already happening.
5. There have been many powerful movies already made that have addressed this issue. Here are two: The Future of Food, Food, Inc.