Researchers at the University of Utah wanted to learn if obseity was biologically associated with an unsatifying sex life, and if so, whether this could be treated. Their study of 64 obese men showed that with increased body mass index (BMI), subjects had lower testosterone rates and "diminished ratings for sexual quality of life."
However, it is reversible: subjects who had gastric bypass surgery showed an increase in those same factors. More studies will be necessary (as always seems to be the case with studies) to further sort out the cause-and-effect relationships.
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