One can argue it was the calorie restriction and not the bacteria. However, the interesting part was that the pathogen then caused the mice to gain weight.
But hey, perhaps they can get a study going on it to determine the causal relationship between the endotoxin, human obesity, and intestinal flora.
A magic bullet in this case would be something that allowed weight reduction with no restriction of calories. From experience, restricting calories long-term is very difficult.