sciencehabit (1205606) writes "What makes some people slender and others full-figured? It's not quite as simple as calories in and calories out. Besides diet and genetics, the community of microbes that lives inside us may be partially responsible for what we weigh. New research on twins suggests that lean people harbor bacteria that their obese counterparts don't have. And, given the chance, those bacteria may be able to prevent weight gain in others."
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