So, you asked, here goes: conventional (nutrition) wisdom has a hypothesis that eating fat makes you fat, a hypothesis that has been going on for about fifty years. To date, as I understand it, this hypothesis has not been scientifically proven, but appears to be adequately disproven by the expanding waistlines of most western cultures. So, what you may ask has this to do with bread? It has been scientifically proven that the human body has one hormone that regulates an over supply of glucose in the blood stream, Insulin. It has also been proven that there are a good handful of hormones that regulate an under supply of glucose in the bloodstream, evolution appears to have created the one hormone based on availability of glucose, which would suggest that we evolved without access to a glucose over supply....
The carrier of our glucose supply is carbohydrates, these are broken down into the simplest form and moved into the bloodstream, the body secretes Insulin to ensure that not too much stays in the blood stream (cos that's bad for us) and then lets Insulin do the magnificent job that it does... It packs up the glucose and checks to see if our muscles need any, once full they say no and Insulin then does the next best thing.... Talks to the fat cells, they open their doors and in goes glucose, as fat, to be used at a later date.
Interestingly, our bodies are little beauties, we can actually create glucose internally should we have an under supply from external sources and so, some questions begin to arise, why do we need to create new foods from grains (which have built pretty good defence mechanisms in trying NOT to be eaten) that are predominantly carbohydrate loaded? Mainly because we have been led to believe that we NEED more carbohydrates, and so we have been given them. We have an absolute abundance of refined carbohydrates in, or, as our food and the saddest thing is that this abundance is a key factor to the trigger of Insulin to promote fat accumulation.
Studies are showing that We have lots of other serious issues with having Insulin flooding our systems on such a regular basis (breakfast, bread; lunch, sandwich; dinner, maybe a roll to mop up gravy?), and whilst these studies continue, the impact of insulin in our daily lives, at levels that we were not genetically designed to handle, gets more and more scary, diabetes is just the tip of the iceberg.
The hypothesis that carbohydrates make you fat (in over abundance) carries with it significant scientific fact, based on the single hormone Insulin. The hypothesis that fat makes you fat is being disproven, daily, by the people that buy low fat milk, don't eat meat, bacon or eggs and shy away from healthy natural foods, instead to gorge on baked goods and pastries, who are clearly overweight and most likely blame a lack of exercise for their current rotundness.