This study aims to verify the extent to which a diversification of carbohydrates and fats intake in a diet, together with the reduction in vitamin D deficiency, impact the levels of hormones (testosterone, estradiol, cortisol) and Sex Hormone Binding Globulin (SHGB) in men doing strength training. The research involved 55 men aged 19-35. The participants were divided into two groups following two interventional diets for 12 weeks: high-fat diet (LCHF) or high-carb diet (LFHC), which were applied to satisfy the caloric requirements of each participant. Moreover, vitamin D supplementation was included. Moreover, both before and after following interventional diets, the level of hormones in participant's blood was examined. After 12 weeks of following interventional diets in both groups, no changes of the levels of testosterone and estradiol, as well as SHGB, were found. The cortisol level in both groups decreased; however, only in the LFHC group was the change statistically significant (p = 0.03) and amounted to -3.5% (the cortisol level on an empty stomach in this group decreased from 14.17 ± 3.35 to 13.93 ± 2.63 mcg/dl). In both groups, the supplementation of vitamin D brought about a significant change in the level of vitamin D metabolite (25 (OH) D) (p = 0.01). In the LCHF group, the level of metabolite increased by 95%, and by 58.3% in the LFHC group. The increase in vitamin D metabolite in blood was higher in the LCHF group than the LFHC group, which might have resulted from the supplementation of this vitamin.
Keywords: high-carb diet; high-fat diet; strength training; testosterone.