Scientists have identified a protein in milk that increases the metabolic rate by improving and speeding up the function of mitochondria in cells. It should help to prevent obesity and diabetes too. It's also found in bread and beer. They hope that they can add this specific protein as a supplement in the future. In the meantime it explains why people who eat more dairy lose more weight than those who don't.
Here is the link to the science podcast with the details. The news on this is about three quarters of the way through.
The podcast is from the BBC, the naked scientist.