This was just discussed last week in another topic. My wife had an Oxygen magazine that had an article that said exactly that. I think it was entitled "Too much sex" and was a cover story. I read it and it was total bullsh$%t. The author wrote it from an interview with some Indian Eastern Medicine doctor, and actually acknowledged in a couple
of places that this was disputed by Western medicine. The article basically said that sexual fluids were rich in nutrients and hormones and should be retained in the body and that too many ejaculations cause fatigue, loss of immune functioning, and maybe muscle wasting. About the only evidence given was ancient Eastern wisdom.