Creatine is a natural compound that helps your muscles produce energy during high-intensity exercise. Your body makes about 1 to 2 grams of it daily in your liver and kidneys, and you get more from foods like meat and fish. As a supplement, creatine monohydrate is one of the most extensively studied sports nutrition products available, with hundreds of trials confirming it increases strength, power, and lean muscle mass.
How Creatine Powers Your Muscles
Your cells run on a molecule called ATP, which is essentially the energy currency your body spends every time you contract a muscle, think a thought, or do anything at all. The problem is that your muscles only store enough ATP for a few seconds of intense effort. After that, the spent ATP molecules need to be recharged.
This is where creatine comes in. When you take creatine, your muscles store it as phosphocreatine, a high-energy molecule that acts like a rapid-charging station. The moment your ATP runs out during a heavy lift or a sprint, phosphocreatine donates its energy to rebuild ATP almost instantly. This is the fastest energy regeneration system in your body, far quicker than burning carbohydrates or fat. The result: you can push out a few more reps, maintain power for a few extra seconds, or recover faster between sets.
Phosphocreatine also works as a shuttle, ferrying energy from the parts of your cells that produce it (the mitochondria) to the parts that use it. So creatine isn’t just a backup battery. It’s also part of the delivery system that keeps energy flowing where it’s needed.
Strength, Power, and Muscle Growth
Because creatine lets you train harder in short bursts, the downstream effect on muscle building is significant. Clinical trials consistently show that people who supplement with creatine during resistance training gain more lean mass than those training with a placebo. In one analysis of randomized trials, creatine users saw upper-body lean tissue increase by roughly 7%, with lower-body gains around 3% and trunk gains around 2%, compared to placebo groups.
The International Society of Sports Nutrition calls creatine monohydrate “the most effective ergogenic nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training.” That’s a strong endorsement from a body that reviewed hundreds of studies before issuing it. The benefits are most pronounced in activities that rely on short, explosive efforts: weightlifting, sprinting, jumping, and interval training. Endurance activities like long-distance running see less benefit because they rely on slower energy systems.
Effects on the Brain
Your brain is one of the most energy-hungry organs in your body, and it uses the same ATP system your muscles do. A systematic review of randomized controlled trials found that creatine supplementation improved short-term memory and performance on intelligence and reasoning tasks. One study found that oral creatine significantly improved scores on a reasoning test done under time pressure, with highly significant results.
The cognitive benefits appear strongest in people under some form of stress, whether that’s sleep deprivation, mental fatigue, or aging. Vegetarians, who get little creatine from food, also showed more pronounced memory improvements compared to meat eaters. For well-rested, well-fed younger adults, the cognitive effects are less consistent. Results on attention, reaction time, and long-term memory have been mixed across studies, so creatine isn’t a universal brain booster, but it does seem to help when your brain is working under less-than-ideal conditions.
Where You Get Creatine From Food
Red meat and poultry are the richest dietary sources. Raw beef contains roughly 4 to 4.5 milligrams of creatine per gram of meat, which works out to about 1.8 to 2 grams per pound. Chicken is nearly identical at around 3.8 to 4 milligrams per gram. Fish, particularly herring and salmon, contains similar amounts. Cooking reduces creatine content somewhat as some of it breaks down with heat or leaches into juices.
Even with a meat-heavy diet, you’ll typically consume only 1 to 2 grams of creatine per day from food. That’s well below the 3 to 5 grams used in most supplementation protocols, which is why supplements have a measurable effect beyond what diet alone provides. Vegetarians and vegans get almost no dietary creatine, which may explain why they tend to show larger responses to supplementation.
How to Take It
The standard approach involves two phases. A loading phase of 20 to 25 grams per day (split into 4 or 5 doses) for 5 to 7 days saturates your muscles quickly. After that, a maintenance dose of 5 to 7 grams per day keeps levels topped off. If you’d rather skip the loading phase, taking 3 to 5 grams daily will get you to full saturation in about 3 to 4 weeks instead.
Timing doesn’t seem to matter much. There’s no strong evidence that taking creatine before a workout outperforms taking it after, or vice versa. Consistency matters more than timing. Taking it at the same time each day helps keep your muscles saturated, and taking it near your workout (either before or after) is a reasonable approach if you want to optimize. Creatine monohydrate is the most studied and clinically effective form. Other forms like creatine hydrochloride or buffered creatine have not shown clear advantages.
Water Retention and Bloating
The most common side effect is weight gain, typically 2 to 4 pounds in the first week or two. This is water, not fat. Creatine is a molecule that attracts and holds water, so as your muscles store more creatine, they also store more fluid. This temporarily increases muscle volume and shows up on the scale. The water weight stabilizes once your muscles are fully saturated.
Some people experience bloating, nausea, or digestive discomfort, particularly during a loading phase when doses are high. Splitting your daily dose into smaller portions throughout the day helps. Taking creatine with a meal or with a non-acidic drink like apple juice or coconut water can also reduce stomach issues. If the loading phase causes problems, skipping it entirely and using a lower daily dose avoids the gastrointestinal symptoms for most people.
Kidney Safety
The concern that creatine damages kidneys is one of the most persistent myths in sports nutrition, and clinical evidence does not support it. A narrative review examining studies lasting up to 21 months found no detrimental effects on kidney function in healthy individuals. This held true across a wide range of populations: resistance-trained men on high-protein diets, postmenopausal women, older adults, and women with fibromyalgia. All kidney markers remained within normal ranges after creatine supplementation.
The confusion partly stems from creatinine, a breakdown product of creatine that doctors use as a marker for kidney function. Creatine supplementation naturally raises creatinine levels in blood tests, which can look like impaired kidney function on paper even when the kidneys are perfectly healthy. If you’re supplementing and get blood work done, it’s worth mentioning your creatine use to your doctor so the results are interpreted correctly.
The one genuine caution applies to people with pre-existing kidney disease. In those cases, creatine could potentially worsen kidney function, and individuals with significantly reduced kidney filtration rates should avoid supplementation.