What is creatine?
Creatine is the most-researched supplement in history — and one of the most relevant to the PepperLedger audience for a reason that has nothing to do with bodybuilding. Every user on a GLP-1 protocol ( semaglutide, tirzepatide) is at risk for lean mass loss — the most clinically significant side effect of GLP-1-driven weight loss. Creatine monohydrate is one of the most evidence-backed tools for preserving lean mass during caloric restriction. This single application makes it essential knowledge for anyone tracking a GLP-1 protocol.
The mechanism for lean mass preservation is straightforward: phosphocreatine in muscle provides the immediate energy substrate for high-intensity contractions. More phosphocreatine means more capacity for resistance training intensity and volume — which is the primary stimulus for muscle protein synthesis. Creatine also increases intramuscular water content (cell volumisation), which is an anabolic signal for protein synthesis. The result: users supplementing creatine during caloric restriction consistently maintain more lean mass than those who do not.
The cognitive evidence is the most underappreciated aspect of creatine. The brain is an energy-demanding organ — neurons maintain their own phosphocreatine pools, distinct from muscle. Multiple RCTs have shown creatine improves cognitive performance under conditions of mental fatigue and sleep deprivation. Vegetarians and vegans — who have low dietary creatine intake — show particularly large cognitive improvements from supplementation.
For longevity: creatine’s benefits in healthy aging are increasingly recognised independently of performance. It preserves lean mass and functional capacity in older adults (sarcopenia prevention), improves bone density through resistance training support, and maintains cognitive function. The argument for creatine as a longevity compound rather than a performance supplement is increasingly made by longevity physicians including Peter Attia — and the evidence supports it alongside testosterone optimisation for lean mass maintenance in aging.
How it works
Phosphocreatine — ATP Resynthesis
Creatine is stored in muscle as phosphocreatine (PCr) via the creatine kinase reaction: creatine + ATP ↔ phosphocreatine + ADP. During high-intensity contractions, phosphocreatine donates its phosphate group to ADP to regenerate ATP, sustaining high power output before glycolysis or oxidative phosphorylation can catch up. Supplemental creatine increases intramuscular phosphocreatine stores by 15-40%, expanding this ATP buffer and enabling more total work before fatigue.
Cell Volumisation — Anabolic Signal
Creatine increases intramuscular water content through osmotic effects — creatine carries water into muscle cells when taken up. This cell volumisation is an anabolic signal: swollen muscle cells activate mTOR and protein synthesis pathways that interpret volume increase as a growth stimulus. The 1-3 kg weight gain at initiation reflects this water retention in muscle cells, not fat — GLP-1 users should be specifically told this so they do not stop creatine thinking it is counteracting weight loss.
Neurological Phosphocreatine
Neurons maintain their own phosphocreatine pools. Under conditions of high neural demand — cognitive tasks, sleep deprivation, metabolic stress — neuronal ATP demand can outpace supply. Phosphocreatine provides the buffer that sustains neural function during these high-demand periods. Creatine supplementation increases brain phosphocreatine levels (confirmed by 31P-MRS imaging) and improves cognitive performance when this buffer is stressed.
Lean Mass on GLP-1 Protocols
On GLP-1 protocols, reduced caloric intake reduces both fat and lean mass. Creatine preserves lean mass through: maintained training capacity (more phosphocreatine → better resistance training → stronger muscle protein synthesis stimulus), direct anti-catabolic cell volumisation and IGF-1 upregulation, and improved insulin sensitivity through GLUT4 translocation in muscle — complementing GLP-1’s own insulin sensitisation. Creatine + resistance training + adequate protein (1.6g/kg/day) is the evidence-based lean mass preservation protocol.
What the research shows
What the community reports
Creatine has undergone a significant framing shift in the biohacker community — from “bodybuilder supplement” to “longevity essential.”
Common misconceptions
"Creatine causes kidney damage."
This is the most persistent myth about creatine and is not supported by evidence. Multiple long-term safety studies in healthy individuals have found no kidney damage at doses up to 10g/day over years. Creatine raises serum creatinine because creatine is metabolised to creatinine — but this is a dietary effect on a lab value, not a sign of kidney damage. In people with pre-existing kidney disease, medical supervision is appropriate; in healthy individuals, kidney harm from creatine has not been demonstrated.
"Creatine is only for bodybuilders."
The evidence for creatine spans cognitive performance, neuroprotection in Parkinson's and TBI research, sarcopenia prevention in elderly individuals, bone density, and lean mass preservation during GLP-1 therapy or caloric restriction. The bodybuilder association reflects where the research started — not where it currently points.
"Creatine causes hair loss."
One study in rugby players found creatine raised DHT (dihydrotestosterone), which is associated with androgenic alopecia in genetically predisposed individuals. This finding has not been consistently replicated in subsequent research. For users with significant genetic risk for androgenic alopecia, awareness is reasonable — but this is not established evidence of causation, and the magnitude of any DHT increase is modest.
Open PepperLedger to track your creatine protocol →
Free to join. No credit card. Ask the Coach about creatine dosing with GLP-1, cognitive protocols, and lean mass tracking.
Free to join · No credit card · 23-day Pro trial included