Creatine HCl — approximately 41× more water-soluble than creatine monohydrate, dissolving completely in ~21mL water versus 400–600mL for monohydrate. This superior solubility ensures consistent intestinal absorption at lower osmotic load, minimizing GI discomfort common with monohydrate. No loading phase required. The methylation-critical function: endogenous creatine synthesis (Arginine + Glycine → GAA → Creatine via GAMT) consumes ~40–50% of all daily methyl groups from SAMe. Dietary creatine supplementation exerts negative feedback inhibition on AGAT, suppressing GAA production and downstream GAMT-mediated methylation demand — freeing SAMe for higher-priority reactions (neurotransmitters, DNA methylation, glutathione). de França et al. (2015) showed only Creatine HCl — not monohydrate — significantly improved fat-free mass and reduced body fat percentage in recreational weightlifters.