Cluster dextrin (HBCD)

Tier 2 — promising · Intra-workout fuel · Endurance · Gastric emptying

Highly branched cyclic dextrin (HBCD) is an engineered starch with a high molecular weight but very low osmolality (~15 mOsm/L versus ~260 mOsm/L for glucose), enabling rapid gastric emptying with minimal GI distress. A 2024 randomised crossover trial (Morenas-Aguilar, PMID 39644922, N=30) found intra-session HBCD supplementation improved repetition velocity in resistance training in men but not women, and was well tolerated without GI complaints. Earlier small trials showed longer time to exhaustion versus glucose solutions in endurance runners. The total body of human RCTs remains small…

Dose: 30–60 g per hour during exercise lasting over 60 minutes; dissolve in 400–600 mL water. For resistance training, 30–45 g during the session (50 mL portions between sets) is the studied protocol.