Creatine: What It Does, How Much to Take, and What to Ignore

Creatine is the most studied supplement in sports nutrition and the one people most often overthink. The protocol fits in a sentence. The confusion comes from everything bolted onto it: loading phases, cycling on and off, timing windows, exotic forms at double the price, and a hair loss rumor traceable to sixteen rugby players. Here is what the evidence supports and what to do tomorrow morning.

What creatine does inside a muscle

Creatine is not a stimulant and it is not a hormone. Your liver and kidneys make some, you eat some in meat and fish, roughly 0.7 g per 6 oz (170 g) serving, and nearly all of it sits in skeletal muscle, mostly as phosphocreatine.

That phosphocreatine is a battery for short, hard efforts. Sprint, lift, or hit the last thirty seconds of a bike interval and ATP burns faster than aerobic metabolism can replace it, so phosphocreatine covers the gap. Run the battery flat and power output falls off. That is the drop you feel between your third and fifth set.

Most people walk around with muscle stores about 60-80% full. Supplementing raises muscle creatine and phosphocreatine by 20-40% above baseline, and the International Society of Sports Nutrition position stand puts the resulting improvement in high-intensity work capacity at 10-20%, scaled to how much your phosphocreatine rose.

None of that makes you stronger on the couch. A fuller battery means one or two more quality reps per set and faster recovery between intervals. Repeat it across a training block and the extra work turns into adaptation. A dose-response meta-analysis comparing novice and experienced lifters found fat-free mass gains of 1.82 kg in experienced lifters and 1.23 kg in novices, a gap that did not reach statistical significance, with no meaningful effect on fat mass in either group.

The dose, and whether you need to load

The maintenance dose is 3-5 g of creatine monohydrate per day, or about 0.1 g per kg of bodyweight. That is the whole protocol for most people.

Loading is optional and it only changes the calendar. The classic protocol is 0.3 g/kg/day, roughly 5 g taken four times daily for 5-7 days, and it saturates muscle stores inside a week. Take 3 g/day instead and you reach a similar 20% increase after about 28 days. Same destination. Three extra weeks to get there, and no week of choking down four doses a day.

Load if a training block or a test week starts soon. Otherwise take 5 g a day and forget about it.

A few practical notes:

• Larger athletes need more. The position stand suggests 5-10 g/day for athletes with more muscle mass to keep saturated. Over 90 kg, lean toward the top of that range during heavy blocks.
• Consistency beats timing. Saturation is a function of total daily intake over weeks, so the hour you take it matters far less than whether you take it at all. Put it in your morning coffee or your post-session shake, whichever one you never skip.
• Carbs help retention. Ingesting creatine with carbohydrate, or with carbohydrate and protein, has been reported to more consistently promote greater creatine retention. Taking it with a meal is enough. You do not need a dextrose powder.
• Cycling is unnecessary. No human evidence shows the creatine transporter shutting down, and your body does not permanently stop making its own. Stop taking it and stores drift back toward baseline over the following weeks.

Protocols and numbers at a glance

Find your situation in the left column and take the daily dose in the second. The loading column is a choice, not a requirement, and the fourth tells you when the supplement is doing its full job. Every row assumes plain creatine monohydrate.

The 0.3 g/kg and 0.1 g/kg figures come from the ISSN position stand and the ISSN review of common creatine questions. Both scale to total bodyweight, not lean mass. If you want to know how much of that weight is muscle, which is where the creatine ends up, a lean body mass calculator does the split.

Who gets the most out of it

Creatine works for almost everyone who trains hard, but the size of the return varies by who you are.

• Anyone doing strength, power, or repeated sprint work. The strongest evidence base in the supplement literature. Lifting, CrossFit, Hyrox, rowing intervals, anything with maximal efforts and incomplete recovery.
• Vegetarians and vegans. Meat and fish are the only meaningful dietary sources, so plant-based athletes start with lower intramuscular stores, around 90-110 mmol/kg of dry muscle, and tend to see larger gains from supplementing. If you eat no animal products, this is the highest-value thing on the supplement shelf for you.
• Older adults lifting. One study cited in the ISSN review found 14 days of creatine increased grip strength by 6.7% in men and women aged 64-86. Paired with resistance training, most evidence shows it adds lean mass and strength in older adults beyond training alone, and the masters athlete training guide covers that side.
• Postmenopausal women. Twelve months at 0.1 g/kg/day alongside training increased strength and preserved femoral neck bone mineral density in the research the ISSN position stand cites. If bone is a concern, read the bone density guide next.
• Anyone training on short sleep. Creatine may improve cognitive processing under sleep deprivation, with one study finding less deterioration in reaction time, balance and mood after 24 hours awake. No evidence supports a cognitive benefit when you are sleeping normally, so this is insurance, not a nootropic.

Notice who is missing: anyone in a deep calorie deficit expecting creatine to protect muscle on its own, or anyone whose protein intake is nowhere near where it should be. Fix that first with a protein calculator, then add the supplement.

The side effects the research does not support

This is where creatine's internet reputation and its evidence diverge most. A 2025 analysis pooled 685 human clinical trials, covering 12,839 participants on creatine and 13,452 on placebo, averaging about 12.5 g/day for roughly 65 days, in studies running as long as 14 years. Of those studies, 13.7% reported side effects in the creatine group and 13.2% in the placebo group. No significant difference across the 49 side effects evaluated.

The specific fears, one at a time:

• Hair loss. The whole rumor traces to one 2009 crossover study in college rugby players, 16 of whom completed it, that found a 56% rise in DHT. It has never been replicated, and no study has reported hair loss in humans. In 2025 a 12-week randomized controlled trial in 38 resistance-trained men measured DHT, testosterone, follicle count, hair density and cumulative hair thickness at 5 g/day. Nothing differed from placebo.
• Kidney damage. The position stand's language is blunt: no compelling evidence that creatine negatively affects renal function in healthy or clinical populations, including use at up to 30 g/day for 5 years. The honest caveat: existing kidney disease or medication affecting renal function makes this a conversation with your doctor, not a decision to take from a guide.
• Cramping and dehydration. The opposite of the folklore. Several studies report athletes on creatine had a lower incidence of cramping, dehydration and heat illness than those who were not.
• Bloating. Real, and brief. Water retention shows up in the first several days and it is largely intracellular, inside the muscle rather than under the skin. Studies running four to six weeks found no significant increase in total body water.
• Stomach upset. Across those 685 trials, gastrointestinal complaints ran 5.51% of participants on creatine against 4.05% on placebo, not a significant difference. If a 5 g dose does bother you, split it in two and take it with food.

Endurance athletes and the weight question

If you run or ride long, creatine is a more complicated call than it is for a lifter, and the reason is bodyweight.

Loading produces short-term fluid retention of roughly 0.5-1.0 L, and the acute weight gain tracks it. For a marathoner that is real mass to carry up every hill for three hours, with no phosphocreatine payoff at threshold pace, because the phosphocreatine system barely participates in steady aerobic work. A race weight calculator puts the number in context against what you are targeting on race day.

The case for taking it anyway is the work around the race. Interval sessions, hill repeats, the winter strength block, the sprint at the end of a criterium, all of it draws on the system creatine supports. There is also evidence that creatine loading before carbohydrate loading promoted greater glycogen restoration than carb loading alone, a genuine if narrow endurance application. Read the carb loading guide first.

The practical shape: 3-5 g daily through base and build, no loading phase so you never take on a kilo of water in a week, and no first-time creatine inside two weeks of a goal race. Novel supplement plus taper is a variable you did not need.

Buying it: monohydrate, and nothing clever

An analysis of 175 creatine products on Amazon found 16 forms of creatine other than monohydrate on sale. Monohydrate-only products averaged $0.12 per gram. Alternative-form products averaged $0.26, about 116% more. Roughly 88% of those alternatives were classified as having limited to no evidence supporting bioavailability, efficacy or safety, and only 8% of the products surveyed carried third-party certification.

Creatine HCl, buffered creatine, creatine ethyl ester, liquid creatine, creatine nitrate. Every one costs more and carries less research, and none has been shown to beat monohydrate at getting creatine into muscle. The position stand is direct that claims of superior uptake for other forms are unfounded.

What to buy: plain creatine monohydrate powder, unflavored, in a tub big enough to last a few months, from a brand that carries third-party testing. At the monohydrate price in that survey, 5 g a day runs about $0.60. Spend the difference on food, where it does more, and check what your macros are doing first.

FAQ

Do I need a loading phase?

No. Loading only changes how fast you get there. Taking 20 g a day split into four doses saturates muscle stores in 5-7 days, while 3 g a day reaches a similar 20% increase in about 28 days. Both end at the same place. Load if you have a training block or a test starting next week. Otherwise take 5 g daily and let it fill over the month.

Does creatine cause hair loss?

The evidence says no. The claim traces to one 2009 study of 16 rugby players that found a rise in DHT. It was never replicated, and no study has ever reported hair loss from creatine. A 12-week randomized controlled trial published in 2025 measured DHT, testosterone, follicle count, hair density and hair thickness in men taking 5 g a day. No difference from placebo on any of them.

Is creatine bad for your kidneys?

Not in healthy people at normal doses. The ISSN position stand states there is no compelling evidence that creatine negatively affects renal function in healthy or clinical populations, including long-term use at up to 30 g a day for five years. Creatine does raise blood creatinine slightly, which can look like a red flag on a lab panel without being one. If you have existing kidney disease, ask your doctor before starting.

Should I take creatine on rest days?

Yes. Creatine works by keeping muscle stores saturated, not by doing something acute on the day you train. Skipping rest days lets stores drift down and slows the process. Take the same 3-5 g every day, training or not, attached to something you already do daily like breakfast or coffee.

Does creatine make you gain weight?

Some, and most of it is water inside the muscle. Loading produces roughly 0.5-1.0 L of fluid retention in the first week, which shows up on the scale. Studies running four to six weeks found no significant increase in total body water. Skip the loading phase and the jump is smaller and slower. Lifters generally want that weight. Marathoners often do not.

Do women need a different dose?

No, the dose is the same 3-5 g a day, or about 0.1 g per kg. The research base in women is smaller than in men but points the same direction for strength and lean mass. It gets more interesting after menopause, where twelve months at 0.1 g/kg/day alongside training increased strength and preserved femoral neck bone mineral density in the trials the ISSN position stand cites.

How Movement Rebels fits

Creatine is a decision you make once and then stop thinking about. What keeps mattering is everything around it.

Write "started creatine, 5 g a day" into Notes for your coach and the Movement Rebels AI coach carries that context into the sessions it writes. Two weeks in, when your logged squat and deadlift sets are moving more weight while your Garmin resting heart rate and sleep hold steady, it reads that as adaptation and keeps the block progressing. If the same lifts stall while your HRV drops and your morning check-ins come back at a 4 out of 10, it pulls volume back instead. Your strength log and your watch data sit in the same brief, so the coach reads them against each other.

Get the boring part right first. Five grams of monohydrate, daily, in whatever you are already drinking.