Creatine: what it does, how to take it and what about the water

What does creatine do in the body?

Creatine fills the energy stores in your muscles that get tapped first during short, intense efforts. About two thirds of it is stored in the muscle as phosphocreatine. That replenishes ATP, the muscle cell's energy currency, within seconds. This is exactly the energy you need for a heavy set, a sprint or a jump.

Your body makes some creatine itself in the liver and kidneys, and you also get it from meat and fish. A supplement fills the stores beyond their usual level. That does not build muscle by itself. But it helps you do a little more in training, and combined with strength training this leads to more strength and muscle mass over the weeks. That is why the International Society of Sports Nutrition (ISSN) calls creatine monohydrate the most effective performance-enhancing supplement currently available to athletes (Kreider et al., 2017).

How much creatine should you take?

3 to 5 g of creatine monohydrate a day is enough. That fills your stores completely, and more gives you no extra benefit for strength or muscle growth. A loading phase is possible but not necessary. It just gets you to the same place faster.

A worked example for a body weight of 80 kg (176 lb): for the loading phase, the ISSN gives about 0.3 g per kilogram of body weight (Kreider et al., 2017). That is 80 × 0.3 = 24 g a day, split into four servings of 6 g each, for five to seven days. After that you continue with 3 to 5 g a day. Larger single doses can upset your stomach, which is why you split them up (Antonio et al., 2021). Without a loading phase, you simply take 3 to 5 g from day one.

A classic study shows that both routes lead to the same place: with 20 g a day, muscle creatine content rose by around 20% within six days. With 3 g a day, a similar level was reached after 28 days (Hultman et al., 1996).

The time of day you take creatine is secondary, what counts is the daily amount. The easiest way is to tie it to a fixed meal. In studies, creatine was stored in muscle somewhat more reliably when taken with carbohydrates, or with carbohydrates and protein. You do not need to take breaks: there is no evidence that the body permanently cuts back its own production. If you stop, your stores drop back to baseline over four to six weeks (Kreider et al., 2017).

Why does creatine make your weight go up?

Your weight goes up because your body holds more water. It is not fat, creatine does not increase fat mass. A loading phase with 20 g a day usually adds 1 to 3 kg on the scale, mostly water (Antonio et al., 2021).

In one study, participants took 25 g a day for seven days and then 5 g a day for three weeks. After 28 days they were 1.31 kg heavier on average, and their total body water was around 2 litres higher. The ratio of water inside and outside the cells stayed the same (Powers et al., 2003). So the extra water does not simply shift into the tissue under your skin. Over longer periods, studies found no more increase in body water relative to muscle mass (Antonio et al., 2021).

This matters most during a diet. If you start creatine in the middle of a deficit, your weekly average might rise from 82.0 to 82.8 kg, for example, even though you are still losing fat. So do not count the first two to three weeks as a setback, and only start comparing week against week again after that. How to tell water from fat on the scale is explained in the article Weight going up in a calorie deficit: water or fat? The simplest option is to start creatine between two phases rather than in the middle of a diet.

Which creatine should you buy?

Buy plain creatine monohydrate. It is by far the best-researched form (Kreider et al., 2017), and other forms have not proven superior to it (Antonio et al., 2021). More expensive versions with new names therefore give you no advantage. Powder or capsules makes no difference, as long as you get to 3 to 5 g a day. With capsules, work out how many you need for that. It is often more than you would think.

Supplements are not checked by the authorities before they go on sale. That is why it pays to look at quality: independent test seals and a certificate of analysis for the specific batch are good signs. Which seals test what is covered in the free Supplements guide.

Is creatine bad for your kidneys or hair?

For healthy people, no, based on everything research has shown so far. The ISSN found no convincing evidence that creatine monohydrate causes harm in the short or long term, including in studies with up to 30 g a day over five years. There is also no convincing evidence of kidney damage (Kreider et al., 2017).

The worry about hair loss goes back to a single study in which the hormone DHT rose. That result has not been confirmed, and no study in humans has shown hair loss from creatine (Antonio et al., 2021).

Who is creatine worth it for?

Creatine is worth it if you do strength training regularly and the basics are already in place. That applies to women just as much as to men, and at an older age too, with the biggest benefit when combined with strength training (Antonio et al., 2021). Protein and creatine are the two supplements I recommend first to most people who train.

Still, creatine remains a supplement. If your protein needs are not covered or your calories do not match your goal, 5 g of powder will not change much. The calorie calculator works out how much you should eat for building muscle or for a diet, and why a small calorie surplus for muscle growth is enough is something I explain in a separate article.

When to check with a doctor

Talk to your doctor before you start if you have a known kidney condition. With existing kidney problems this is explicitly recommended as a precaution (Kreider et al., 2017). The same applies if you have a liver condition, regularly take several prescription medications, or are pregnant, breastfeeding or planning a pregnancy.

Creatine can also raise creatinine levels in blood and urine. This value is used to estimate kidney function, so a higher reading can falsely look like a kidney problem (Antonio et al., 2021). That is why you should mention that you take creatine before having blood drawn. This article does not replace medical advice.