Totally fascinating last night.
I too am surprised we're not even more obese given the larger portions and the more calorie dense foods.
We should really all be in an Aldous Huxley novel by now 
I love the research that proves that it doesn't matter how much you eat at lunch you don't reduce what you eat at dinner naturally. And that if you increase portion size we quickly get used to it.
I honestly believe every snack food should be in an individual portion size (none of that fake 'sharing' marketing wet dream bollocks) and there should be legislation around it.
We are biological beings programmed to eat more in times of plenty - give someone a large bag of crisps and they will, without thinking or awareness, eat more than they would have in a single portion size.
This does not make them greedy, slovenly, or stupid - it makes them human. And I think it doesn't just make them individually responsible - it's a public health issue IMO.