Figure 1.

Observational data (n = 47) showing an inverse correlation between protein intake and total testosterone, which weakens when participants > 2.5 g/kg/day of protein are removed. Volek et al. (1997) protein intake converted from the percentage of total energy intake. All data extracted from graphs using WebPlotDigitizer (Rohatgi, 2022), incurring very minor differences from the original data. Volek et al. (1997) and Sallinen et al. (2004): serum testosterone; Toma (2009): plasma testosterone. g/kg/day: g/kg of bodyweight/day.