Creatine is one of the most well-studied supplements in sports nutrition, and its primary benefit is helping your muscles produce energy faster during intense exercise. That translates into measurable gains in strength, muscle mass, and power output. But the benefits extend beyond the gym, with growing evidence for improvements in brain function, healthy aging, and recovery from brain injury.
How Creatine Works in Your Body
Your muscles run on a molecule called ATP, which is essentially the energy currency of every cell. The problem is that your muscles only store enough ATP for a few seconds of all-out effort. Creatine, stored in muscle as phosphocreatine, acts as a rapid backup system. It donates a high-energy phosphate group to rebuild ATP almost instantly, letting you sustain hard efforts for longer before fatigue sets in.
About 95% of your body’s creatine is stored in skeletal muscle. Your body makes some on its own and you get more from meat and fish, but supplementation raises those stores well above what diet alone provides. Once your muscles are fully saturated with creatine, you have a larger energy buffer available for short, explosive activities like sprinting, lifting heavy weights, or jumping.
Strength and Power Gains
The performance benefits are substantial and consistent across dozens of trials. A review of 22 studies found that people who took creatine while resistance training increased their muscle strength by about 20% on average, compared to 12% for those training with a placebo. That 8-percentage-point gap is meaningful, especially over months of training. Weightlifting performance, measured as the number of reps you can do at a given weight, showed an even larger gap: 26% improvement with creatine versus 12% without. For bench press specifically, one-rep max improvements ranged from 3% to 45% across studies, with rep performance gains of 16% to 43%.
These aren’t small differences, and they compound over time. More reps per set and heavier loads mean more total training volume, which drives further muscle and strength development.
Building More Muscle
A meta-analysis of older adults found that creatine supplementation during resistance training produced roughly 1.4 kilograms (about 3 pounds) more lean tissue mass than resistance training with a placebo. That finding held up even after researchers excluded studies that combined creatine with other supplements or included people with chronic health conditions. The extra lean mass comes from two sources: an initial increase in water stored within muscle cells, and over time, greater actual muscle growth driven by the ability to train harder.
Creatine is an osmotically active substance, meaning it pulls water with it wherever it’s stored. Since nearly all of it sits inside muscle, supplementation increases total body water. Research measuring fluid distribution found that body water increased but remained normally distributed between the inside and outside of cells, so the water retention doesn’t cause the puffy, bloated look some people worry about. Early weight gain of 1 to 2 kilograms in the first week of supplementation is almost entirely water, not fat.
Brain Function and Mental Performance
Your brain is one of the most energy-hungry organs in your body, and it relies on the same phosphocreatine system that powers your muscles. Supplemental creatine increases energy supply to neurons in healthy adults, which is why researchers have been testing its effects on cognition.
A systematic review of randomized controlled trials found evidence that creatine can improve short-term memory and reasoning ability. Forward and backward recall tasks, long-term memory, and spatial memory all showed significant improvement in creatine groups compared to placebo in multiple studies. The effects on other cognitive domains like reaction time, attention, and mental fatigue were less consistent, with some studies showing benefits and others showing none.
One particularly interesting finding: vegetarians showed clearer cognitive improvements from creatine than meat-eaters in at least one trial, likely because their baseline brain creatine levels were lower to begin with.
Benefits for Older Adults
Age-related muscle loss, known as sarcopenia, is one of the biggest threats to independence as people get older. Creatine paired with resistance training has shown consistent benefits in this population. A meta-analysis found that creatine plus exercise significantly increased one-rep max strength in older adults, with one review noting it could double the strength gains from resistance training alone.
The benefits go beyond raw strength. Older adults taking creatine showed improved chair-rise performance, greater gains in fat-free mass, and a small but significant reduction in body fat percentage. In vulnerable older women, long-term creatine use enhanced appendicular lean mass (the muscle on your arms and legs that matters most for daily function) and improved overall muscle function when combined with resistance training. These effects have been observed in study durations ranging from 7 to 52 weeks, with training frequencies of two to three sessions per week.
Extra Relevance for Vegetarians and Vegans
Creatine is found naturally in red meat, poultry, and fish. People who eat little or no animal products consistently show lower baseline creatine stores in both muscle and brain tissue. This means vegetarians and vegans often have more room to benefit from supplementation. Both physical and cognitive performance improvements tend to be more pronounced in plant-based eaters, making creatine one of the few supplements with an especially strong case for this group.
Concussion and Brain Injury Recovery
Brain creatine levels drop after a mild traumatic brain injury or concussion, and early research suggests supplementation could help with recovery. Creatine has shown some promise for reducing symptoms of concussion and mild traumatic brain injury, as well as some indicators of depression. The evidence here is still limited compared to the exercise performance data, but the biological rationale is strong: restoring depleted brain energy reserves could support healing.
How to Take It
The standard protocol involves a loading phase of 20 to 25 grams per day (split into 4 or 5 doses) for 5 to 7 days, followed by a maintenance dose of 5 to 7 grams per day. The loading phase saturates your muscle stores quickly. If you skip it and just take the maintenance dose from day one, you’ll reach the same saturation level, but it takes about 3 to 4 weeks instead of one. Either approach works. Creatine monohydrate is the most studied and most cost-effective form.
Safety and Kidney Concerns
The most persistent concern about creatine is that it damages the kidneys. This worry stems from the fact that creatine supplementation raises serum creatinine, a waste product that doctors use as a marker of kidney function. Higher creatinine on a blood test can look alarming, but in this case, it reflects increased creatine turnover, not kidney damage.
A systematic review and meta-analysis found no significant changes in glomerular filtration rate (the gold-standard measure of how well your kidneys actually filter blood) following creatine supplementation. Even in studies lasting longer than 12 weeks, where creatinine levels rose more noticeably, kidney function itself remained preserved. The authors concluded that creatine is likely safe for kidney function in healthy individuals and various clinical populations when used at standard doses. If you’re getting bloodwork done while taking creatine, it’s worth mentioning your supplementation so your doctor can interpret creatinine levels in context.
The only consistently documented side effect is weight gain from water retention, typically 1 to 2 kilograms in the first week. Anecdotal reports of cramping and digestive issues exist, but controlled studies have not confirmed these as direct effects of creatine at recommended doses.