High-intensity exercise inhibits appetite in part via alterations in the peripheral concentrations of the appetite-regulating hormones acylated ghrelin, active glucagon-like peptide-1 (GLP-1), and active peptide tyrosine-tyrosine (PYY). Given lactate may mediate these effects, we utilized sodium bicarbonate (NaHCO 3 ) supplementation in a double-blind, placebo controlled, crossover design to investigate lactate's purported role in exercise-induced appetite suppression. Eleven males completed two identical high-intensity interval training sessions (10 x 1 min cycling bouts at ~90% heart rate maximum interspersed with 1 min recovery), where they ingested either NaHCO 3 (BICARB) or sodium chloride (NaCl) as a placebo (PLACEBO) pre-exercise. Blood lactate, acylated ghrelin, GLP-1, and PYY concentrations, as well as overall appetite were assessed pre-exercise and 0, 30, 60, and 90 min post-exercise. Blood lactate was greater immediately (P<0.001) and 30 min post-exercise (P=0.049) in the BICARB session with an increased (P=0.009) area under the curve (AUC). The BICARB session had lower acylated ghrelin at 60 (P=0.014) and 90 min post-exercise (P=0.016) with a decreased AUC (P=0.039). The BICARB session had increased PYY (P=0.034) with an increased AUC (P=0.031). The BICARB session also tended (P=0.060) to have increased GLP-1 at 30 (P=0.003) and 60 min post-exercise (P<0.001) with an increased AUC (P=0.030). The BICARB session tended (P=0.059) to reduce overall appetite, though there was no difference in AUC (P=0.149). These findings support a potential role for lactate in the high-intensity exercise-induced appetite-suppression.