These findings all point to the fact that short-term fasting does not have any negative effects on testosterone levels, and certainly would not cause serum testosterone levels to ever drop below normal. In fact, based on this evidence this may be one area where brief periods of fasting are actually better than prolonged dieting — since the short periods of fasting do little to disrupt testosterone levels, whereas longer more sustained periods of caloric restriction do seem to negatively affect testosterone levels in men.
