It seems that a lot of people are threatened by simple truths in this film. Fat people don't want to be told that their food choices are being influenced by advertising. The negative ratings come from the mirror held in front of the faces of the audience, the negativity is a reflection of the shame of being overweight or the reflection of their own brands that they are wearing and the value they put in them.
This is an original film that doesn't fit the current Hollywood blockbuster mold, but rather it requires self-examination of what influences human choices.
There are a lot of word salad reviews on this movie already, no need for another. Go in with no expectations, come out with a cleaner view of the world and start to understand why you're craving your McDonalds/Coke/Idevice.
Check it out and be pleasantly rewarded - unless your own reflection reflects something too unpleasant to accept....