Acute decrease in plasma testosterone and appetite after either glucose or protein beverages in adolescent males.
Level 2 - randomized trial
Randomized crossover trial
PubMed 31055857 · doi:10.1111/cen.14005
What was done
Twenty-three adolescent males aged 12 to 18 years participated in a randomized crossover study testing three beverages: whey protein (1 g/kg body weight), glucose (1 g/kg body weight), and a calorie-free control. Plasma testosterone, luteinizing hormone (LH), active GLP-1, acylated ghrelin, glucose, insulin, and subjective appetite were measured at baseline (0 minutes) and at 20, 35, and 65 minutes post-ingestion. Ad libitum food intake at a pizza meal was assessed at 85 minutes.
What was found
Plasma testosterone decreased acutely by 20 minutes after both protein and glucose ingestion; this decrease persisted to 65 minutes after protein but not glucose (P = 0.0382). LH was also decreased by both protein and glucose, though glucose showed no effect at 20 minutes compared to protein (P < 0.001). Plasma testosterone correlated positively with LH (r = 0.58762, P < 0.0001) and negatively with GLP-1 (r = -0.50656, P = 0.0003). No associations were observed with appetite, ghrelin, or glycemic markers. Food intake at the ad libitum meal was not affected by treatments. Absolute hormone values and baseline concentrations were not reported in the abstract.
Why it matters
This study demonstrates that acute intake of both carbohydrate and protein rapidly suppresses testosterone and LH in adolescent males, showing that postprandial testosterone drops do not acutely drive food intake.
Limits
The study is limited by a small sample size (n = 23) restricted entirely to adolescent males, limiting generalizability to adult men or females. Measurements were limited to a brief 85-minute window following a single challenge, and absolute values for hormone changes were not provided in the abstract.
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