The results from these studies do not provide any conclusive evidence regarding soy protein having a negative effect on testosterone production. In addition, muscle androgen-responsive mRNA was increased in all groups as a result of the training stimulus (significant main effects for time), but no significant differences were observed between the three groups. Kraemer and colleagues examined the effect of soy protein supplementation on the testosterone and estradiol response in healthy, resistance-trained men. Dietary protein supports the replenishment of skeletal muscle protein as it is degraded or damaged by intense exercise 94,95. Skeletal muscle, the site for force production, is predominantly comprised of protein . For carbohydrate and fat, one study showed no effect , one study showed an increase after the exchange of 65 en% fat for carbohydrate , and one study showed the opposite, a decrease after the exchange of 28 en% fat for carbohydrate . In a second study, with a similar energy exchange with alcohol, there was a significant increase in DIT, from 7.1 to 9.0 % of the energy content of the meal . The experimental design of most studies on DIT is a measurement of resting energy expenditure before and after a test meal, with a ventilated hood system. The postprandial rise in energy expenditure lasts for several hours and is often regarded as completely terminated at approximately 10 hours after the last meal but there is still an argument as to when the post absorptive state is reached. Protein plays a key role in body weight regulation through satiety related to diet-induced thermogenesis. Values are higher at a relatively high protein and alcohol consumption and lower at a high fat consumption. The popularity of soy protein use among vegan athletes has resulted in a focus on its effect on sport performance and changes in testosterone concentrations. One type of protein that has received considerable attention regarding its effect on circulating testosterone concentrations is soy protein. The LFD had a small-to-moderate effect on decreasing total testosterone concentrations compared to the HFD. Although both groups had similar increases in muscle thickness, lean body mass, and strength measures (1RM squat and bench press), only the KD group experienced a significant increase in TT concentrations. Results indicated that both groups experienced a significant increase from baseline in both total testosterone (TT) and FT concentrations during all four assessment times (weeks 2, 4, 6, and 8) of the study. Cholesterol, a dietary fat component, is one of the building blocks for testosterone production . Effect of low energy availability and energy deficits on circulating testosterone concentrations. Interestingly, Almstrup and colleagues reported that red clover flowers inhibit aromatase activity at low concentrations, but become estrogenic at higher concentrations, resulting in a U-shaped dose–response curve. Shufelt and colleagues reported that red wine consumption resulted in significantly higher FT concentrations and lower SHBG and E2 concentrations in women. Jeong and colleagues reported four compounds isolated from this plant, including diethyl ether extract, inflexin, ursolic acid, and ursolic acid 3-O-acetate that have significant aromatase inhibitory activity. The effect of various food groups, macronutrients, and micronutrients on testosterone circulation and its proposed mechanisms. While other reviews have previously discussed the effect of nutrition on testosterone status 13,14,15,16, most of these papers have examined the role of single nutrient (macro/micro) or food/food groups. Working with your metabolism through protein adequacy, food quality, movement, sleep, and stress management offers a more sustainable path than fighting your body with ever-lower calorie targets. Metabolic adaptation means your body can adjust energy expenditure in response to intake. The thermic effect of food means protein calories are processed less efficiently than fat calories. While the microbiome is one factor among many, supporting its health through dietary fiber, fermented foods, and potentially beneficial probiotics may contribute to better metabolic outcomes.
