Low-dose alcohol

  • In 2003 Alcoholism, Clinical and Experimental Research published a double-blind, placebo-controlled crossover trial which found that .5 g/kg alcohol (roughly two drinks for an average sized male) lead to an 18 percent increase in free testosterone levels. [Source]

Interval training

  • In 2012 the Journal of Endocrinological Investigation published a study of 15 endurance-trained males which showed that high-intensity interval training triggered a greater testosterone response compared to steady state endurance exercise. [Source]


  • In 2001 The Journal of Nutrition published an animal study which found that rats fed high-protein diets supplemented with garlic powder for 28 days had a significantly higher testosterone contents in the testis compared to rats fed the same diet without garlic powder. [Source]

Vitamin D Supplementation

  • In 2011 Hormone and Metabolic Research published a study in which 200 healthy, overweight subjects, deficient in vitamin D, received either 3,332 IU vitamin D daily or a placebo for one year. Significant increases were seen in testosterone levels in the vitamin D group compared to no change in the placebo group. [Source]


  • In 2013 the European Journal of Applied Physiology published a double-blind, placebo-controlled clinical trial which found that in middle-aged men, DHEA supplementation both elevated free testosterone levels and prevented declines during HIIT (high intensity interval training). In a placebo group significant declines in testosterone were seen following HIIT training. [Source]


  • In 2014 the Journal of Strength and Conditioning published a crossover study in which 10 resistance trained men completed 6 sets of 10 repetitions of both squats and legs presses separated by one week.  Blood tests collected before and after exercises showed that squats increased both testosterone and growth hormone more than leg presses. However, squats also led to greater increases in cortisol levels. [Source]


  • In 2015 the Journal of the International Society of Sports Nutrition published a double-blind, placebo-controlled study in which 57 males with little resistance training experience received either 300 mg of ashwagandha or a placebo twice daily. After 8-weeks of resistance training the ashwagandha group had significantly greater strength increases in bench-press and leg extension as well as greater increases in muscle size and testosterone levels and greater reductions in exercise-induced muscle damage. [Source]


  • In 2012 the Journal of Pharmacology & Pharmacotherapeutics published an animal study which found that Tribulus terrestris dose-dependently increased sexual behavior in rats. Chronic administration also increased testosterone levels with no toxic effects observed. [Source]
  • In 2008 Phytomedicine published an animal study which found that Tribulus terrestris increased the levels of testosterone and other hormones involved in sexual function. The authors of the study concluded that Tribulus terrestris may be useful in mild to moderate cases of erectile dysfunction.


  • In 2010 the Journal of Strength and Conditioning published a double-blind, placebo-controlled study of 17 strength-trained athletes which found that, based on blood samples taken during and after exercise, arginine and ornithine supplementation significantly increased growth hormone and testosterone levels. [Source]
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