Creatine Dosing by Body Weight: The 0.03g/kg/Day Protocol

Why Body Weight Matters for Creatine Dosing

Creatine is stored almost exclusively in skeletal muscle. Approximately 95% of the body's total creatine pool resides in muscle tissue, with the remainder in brain, kidneys, liver, and testes. The total creatine pool scales roughly linearly with total muscle mass. A 60 kg individual with moderate muscularity has a substantially smaller absolute creatine pool than a 110 kg individual with high lean mass.

Daily creatine turnover — the irreversible non-enzymatic degradation of creatine and phosphocreatine to creatinine — is proportional to the total pool size. Approximately 1.7% of the total pool degrades each day. For a person with a 120 g total pool, this is roughly 2 g/day. For a person with a 180 g total pool (typical of a heavily muscled individual), turnover may exceed 3 g/day. The daily maintenance dose must replace this turnover to sustain elevated stores.

A flat dose of 3-5 g/day works adequately across a broad range of body sizes because the range itself provides flexibility. A 55 kg person taking 3 g/day receives approximately 0.055 g/kg, while a 100 kg person taking 5 g/day receives 0.05 g/kg. Both are well above the minimum maintenance threshold. However, for individuals at the extremes of body mass — particularly very large, heavily muscled athletes — a weight-based calculation can provide more informed dosing.

The 0.3 g/kg/Day Loading Formula

The weight-based loading dose is approximately 0.3 g/kg/day for five to seven days. This formula was derived from the original studies that used 20 g/day in subjects averaging approximately 65-75 kg body weight. The ISSN position stand (Kreider et al., 2017) endorses this relative loading dose as a means of individualizing the protocol.

Applied across different body weights, this produces the following loading doses:

• 55 kg individual: 0.3 x 55 = 16.5 g/day (divided into 4 doses of approximately 4 g each)
• 70 kg individual: 0.3 x 70 = 21 g/day (divided into 4 doses of approximately 5 g each)
• 85 kg individual: 0.3 x 85 = 25.5 g/day (divided into 4-5 doses of approximately 5-6 g each)
• 100 kg individual: 0.3 x 100 = 30 g/day (divided into 5-6 doses of 5-6 g each)
• 115 kg individual: 0.3 x 115 = 34.5 g/day (divided into 6-7 doses of approximately 5 g each)

The important principle is that heavier individuals have a larger absolute creatine pool to fill and therefore require a larger absolute loading dose to achieve saturation within the standard five-to-seven-day window. Using the flat 20 g/day for a 115 kg athlete would produce 0.17 g/kg/day — significantly below the 0.3 g/kg target — and might result in incomplete saturation within the loading period.

The 0.03 g/kg/Day Maintenance Formula

The weight-based maintenance dose is approximately 0.03 g/kg/day, which is exactly one-tenth of the loading dose. This ratio reflects the fact that maintenance requires replacing only the daily turnover (approximately 1.7% of the pool), rather than filling the entire pool rapidly. Kreider et al. (2017) and Antonio et al. (2021) both reference this relative dosing approach.

Applied across body weights:

• 55 kg: 0.03 x 55 = 1.65 g/day
• 70 kg: 0.03 x 70 = 2.1 g/day
• 85 kg: 0.03 x 85 = 2.55 g/day
• 100 kg: 0.03 x 100 = 3.0 g/day
• 115 kg: 0.03 x 115 = 3.45 g/day

These calculated values are notably lower than the commonly recommended 3-5 g/day range for most body weights. The 0.03 g/kg formula represents the estimated minimum replacement dose. The 3-5 g recommendation incorporates a safety margin that accounts for variability in absorption, individual differences in turnover rate, and days where a dose might be partially missed or suboptimally absorbed. Both approaches produce the same functional outcome — sustained elevated intramuscular creatine stores — but the flat 3-5 g recommendation is simpler and more conservative.

Body Weight vs. Lean Body Mass

A more precise approach would dose creatine based on lean body mass (LBM) rather than total body weight, since creatine is stored in muscle tissue, not adipose tissue. A 100 kg individual at 15% body fat (LBM = 85 kg) has substantially more muscle than a 100 kg individual at 35% body fat (LBM = 65 kg), and their creatine pools and turnover rates would differ accordingly.

However, practical obstacles limit the utility of LBM-based dosing. Accurate body composition measurement requires DEXA scanning, hydrostatic weighing, or similar methods that are not routinely available. BIA scales and skinfold calipers provide rough estimates with significant error margins. For a supplement with a wide therapeutic window and essentially no toxicity at recommended doses, the precision of LBM-based dosing is not justified by any demonstrated clinical benefit.

The pragmatic approach is to use total body weight with the 0.03 g/kg formula as a minimum target, and to round up to the nearest practical dose (since creatine monohydrate is measured in scoops of approximately 3-5 g, not in fractions of grams). For individuals who are significantly overweight or obese, using an estimated LBM or simply defaulting to the lower end of the 3-5 g range is reasonable.

Implications for Lighter Individuals

For individuals at the lower end of the body weight spectrum — such as smaller females, lighter-weight athletes, and adolescents — the weight-based formula produces maintenance doses below 3 g/day. A 50 kg person, for example, would calculate a maintenance dose of only 1.5 g/day. This raises the question of whether such individuals can use less than the standard 3 g dose.

The evidence supports lower doses for smaller individuals. Hultman et al. (1996) showed that 2 g/day maintained elevated stores in subjects of average body weight. For a significantly lighter individual with a proportionally smaller creatine pool and lower absolute turnover, 2 g/day would be expected to exceed the minimum replacement need. There is no strong rationale for a 50 kg person to take 5 g/day; 2-3 g/day should be sufficient.

That said, creatine monohydrate is remarkably safe, and the difference between 2 g and 5 g for a small person is simply more urinary creatine excretion at the higher dose, not any adverse effect. If convenience favors a standard 3-5 g scoop, the excess is harmlessly excreted. The weight-based calculation primarily serves to assure smaller users that they do not need the upper end of the dosing range.

Implications for Heavier Individuals

For individuals above 100 kg, particularly those with high lean body mass (competitive strength athletes, bodybuilders, football linemen), the standard 5 g/day maintenance dose approaches the minimum calculated from the 0.03 g/kg formula. A 120 kg athlete calculates to 3.6 g/day, which is comfortably within the 3-5 g range. Even at 140 kg, the calculated dose is 4.2 g/day — still within the standard range.

Some practitioners recommend that very large athletes (above 100-110 kg of lean mass) take 5-10 g/day for maintenance. While this exceeds the ISSN-recommended maximum of 5 g/day for maintenance, there is no evidence of harm at these doses, and the theoretical rationale (larger pool, higher turnover) is sound. However, the incremental benefit of 10 g versus 5 g has not been validated by controlled trials. The excess is likely excreted renally rather than contributing to further pool elevation.

Antonio et al. (2021), in their updated review of creatine supplementation, noted that while relative dosing provides a useful framework, the absolute doses used in clinical trials (consistently 3-5 g/day for maintenance) have produced reliable benefits across a wide range of body sizes. The 0.03 g/kg formula should be viewed as a lower bound estimate, with the 3-5 g recommendation serving as the practical standard.

Loading by Body Weight: Practical Considerations

Implementing the 0.3 g/kg/day loading protocol for heavier individuals requires additional attention to dose fractionation. A 100 kg athlete loading at 30 g/day should divide this into five or six doses of 5-6 g each, rather than four doses of 7.5 g. Larger individual doses increase the likelihood of GI distress because intestinal absorption becomes less efficient when more creatine is present in the gut at one time.

The spacing of doses remains important: three to four hours between each dose allows plasma creatine levels to decline from the previous peak before the next dose elevates them again. This pulsatile pattern of plasma creatine exposure may be more effective for muscle uptake than sustained high levels, though the evidence on this point is largely theoretical.

For lighter individuals, the loading dose calculation may produce an amount lower than 20 g. A 55 kg person would load at 16.5 g/day. This can be divided into three to four doses of approximately 4-5 g each. The lower absolute dose reduces GI burden while providing adequate plasma creatine exposure for their smaller muscle mass.

Special Populations

Several populations warrant specific consideration for weight-based dosing:

Female athletes: Women generally have lower total muscle mass relative to body weight compared to men. A 65 kg woman with approximately 25 kg of muscle mass has a smaller creatine pool than a 65 kg man with approximately 30 kg of muscle mass. However, the 0.03 g/kg formula based on total body weight provides adequate dosing for both, as it already includes a safety margin. Studies in female subjects (Brenner et al., 2000; Vandenberghe et al., 1997) have shown creatine supplementation to be effective at standard doses.

Older adults: Sarcopenia (age-related muscle loss) reduces total creatine storage capacity. An 80-year-old individual weighing 70 kg may have substantially less muscle mass than a 25-year-old at the same weight. Despite this, creatine supplementation at standard doses (3-5 g/day) produces meaningful benefits in older adults, as demonstrated in multiple trials (Chilibeck et al., 2017). Lower doses based on the weight formula (0.03 g/kg) are likely sufficient.

Adolescents: Younger, growing individuals have different body composition trajectories. Weight-based dosing is particularly appropriate for this population to avoid excessive dosing in smaller adolescents. This is discussed in detail in the companion article on creatine for teenagers.

Practical Dose Calculation Guide

For those wishing to calculate their individualized dose:

1. Loading dose: Multiply body weight in kilograms by 0.3. Divide the result into four to six equal daily doses. Take for five to seven days. Example: 80 kg x 0.3 = 24 g/day, taken as four doses of 6 g or five doses of approximately 5 g.
2. Maintenance dose: Multiply body weight in kilograms by 0.03. Take this amount daily. Round to the nearest practical measurement. Example: 80 kg x 0.03 = 2.4 g/day. Rounding to 3 g (one standard scoop) is appropriate.
3. For body weight in pounds: Divide weight in pounds by 2.2 to get kilograms, then apply the formulas above. Example: 180 lbs / 2.2 = 82 kg. Loading: 82 x 0.3 = 24.6 g/day. Maintenance: 82 x 0.03 = 2.5 g/day.
4. Practical minimum: Do not go below 2 g/day for maintenance regardless of body weight. Below this threshold, daily replacement may not fully offset turnover in all individuals.
5. Practical maximum: Standard maintenance dosing caps at 5 g/day. Doses above this are unlikely to provide additional benefit and simply increase urinary excretion.

Summary

Weight-based creatine dosing (0.3 g/kg/day for loading, 0.03 g/kg/day for maintenance) provides a more individualized approach than the flat 3-5 g/day recommendation, accounting for the relationship between body mass, total creatine pool size, and daily turnover. In practice, the weight-based calculations converge with the standard recommendation for most individuals in the 60-100 kg range. The formula is most useful at the extremes: lighter individuals (below 60 kg) can confidently use the lower end of the dosing range, while heavier individuals (above 100 kg) may need to ensure they reach at least 5 g/day. The standard 3-5 g/day recommendation remains appropriate as a simplified, well-validated guideline for the general population.

Bibliography

1. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. 2017;14:18. doi:10.1186/s12970-017-0173-z. PMID: 28615996.
2. Antonio J, Candow DG, Forbes SC, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition. 2021;18(1):13. doi:10.1186/s12970-021-00412-w. PMID: 33557850.
3. Hultman E, Soderlund K, Timmons JA, Cederblad G, Greenhaff PL. Muscle creatine loading in men. Journal of Applied Physiology. 1996;81(1):232-237. doi:10.1152/jappl.1996.81.1.232. PMID: 8828669.
4. Chilibeck PD, Kaviani M, Candow DG, Zello GA. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access Journal of Sports Medicine. 2017;8:213-226. doi:10.2147/OAJSM.S148357. PMID: 29138605.
5. Brenner M, Rankin JW, Sebolt D. The effect of creatine supplementation during resistance training in women. Journal of Strength and Conditioning Research. 2000;14(2):207-213. doi:10.1519/00124278-200005000-00014.
6. Vandenberghe K, Goris M, Van Hecke P, Van Leemputte M, Vangerven L, Hespel P. Long-term creatine intake is beneficial to muscle performance during resistance training. Journal of Applied Physiology. 1997;83(6):2055-2063. doi:10.1152/jappl.1997.83.6.2055. PMID: 9390981.
7. Harris RC, Soderlund K, Hultman E. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clinical Science. 1992;83(3):367-374. doi:10.1042/cs0830367. PMID: 1327657.