I think its important to think clearly when discussing these issues of overwieght and obesity. We are, basically talking about the biology and physiology of the body. I think its tempting to think of these issues in terms of morality. If you do good things and sacrifice, you get good things. If you do bad things and don't sacrifice, you get bad things. But none of this has anything to do with how the body works.
We know people get fat because they eat too much and/or move too little. That's not the question. The question is why do some people eat too much and move too little. Is it really because they are lazy or gluttonous? The carb/insulin hypothesis says that the arrow of causation is backwards. In other words, we don't get fat because we eat too much and move too little. We eat too much and move little, BECAUSE were getting fat!