A new study reported on in the journal Nature Communications reveals more about the intertwining roles of calories, microbes and metabolism in maintaining human health. The study’s authors include Rosa Krajmalnik-Brown and Bruce Rittmann, professors in the  School of Sustainable Engineering and the Built Environment, part of the Fulton Schools. The journal article describes how loading up microbes with calories can boost the body’s metabolism. Calories energize microbes, suggesting our gut microbes define how efficient our bodies are in extracting calories from our food, says Krajmalnik-Brown, who directs ASU’s Biodesign Center for Health Through Microbiomes. The study could help provide solutions to widespread public health problems.