A study published in the Journal of Steroid Biochemistry studied the effects of diet on serum sex hormones in healthy men. Results showed that when men decreased their healthy fat intake, serum concentrations of androstenedione, testosterone and free testosterone also decreased. (8) This indicates you can add low testosterone to the list of low-fat diet risks.
A loophole in FDA regulations allows pharmaceutical marketers to urge men to talk to their doctors if they have certain "possible signs" of testosterone deficiency. "Virtually everybody asks about this now because the direct-to-consumer marketing is so aggressive," says Dr. Michael O'Leary, a urologist at Harvard-affiliated Brigham and Women's Hospital. "Tons of men who would never have asked me about it before started to do so when they saw ads that say 'Do you feel tired?'"