Putting on a few unwanted pounds? It’s not your fault, it’s your gut bacteria. Yes, gut bacteria, strange creatures that inhabit your stomach, apparently have the keys to your serum cholesterol levels, which exert a major influence on weight gain and loss. How do we know? Researchers at the Alimentary Pharmabiotic Centre in University College Cork have discovered that the bacterial protein bile salt hydrolase, which is made by gut bacteria, has the ability to change the chemical properties of bile acids in the gut. The bile acids, in turn, act as signalling molecules in the host (that would be you), almost like a hormonal network, with an ability to influence host metabolism. In short, the protein reduces serum cholesterol levels and consequently reduces weight gain. See, it’s not your fault. Just one more thing: the research so far has involved mice, not humans. Still, researchers are imagining new ways to control body weight by finding the best mix of gut proteins and putting them to work with probiotics, such as yogurt. Read more from the Alimentary Pharmabiotic Centre in University College Cork.