Creatine—typically bought in flavored powders and mixed with liquid—increases the body’s ability to produce energy rapidly. With more energy, you can train harder and more often, producing faster results.
It’s as simple as this: “If you can lift one or two more reps or 5 more pounds, your muscles will get bigger and stronger,” says Chad Kerksick, Ph.D., assistant professor of exercise physiology at the University of Oklahoma.
Research shows that creatine is most effective in high-intensity training and explosive activities. This includes weight training and sports that require short bursts of effort, such as sprinting, football, and baseball.
There is less support to indicate that creatine improves endurance performance and aerobic-type exercise.
One thing is almost certain: If you take creatine, you’ll gain weight.
It’ll happen quickly, says Paul Greenhaff, Ph.D., professor of muscle metabolism at the University of Nottingham in England. While the initial gain is water (about 2 to 4 pounds in the first week of supplementation), subsequent gains are muscle due to the increase in the workload you can handle.
Because creatine is an “osmotically active substance,” it pulls water into your muscle cells, which increases protein synthesis, Kerksick says.
Studies in the journal Medicine & Science in Sports & Exercise found that muscle fibers grow when a person takes creatine.
The catch: This only happens if you take advantage of the boost in energy and hit the gym. Otherwise, it is just water weight.
Nobody argues with any of this. But there are some questions about creatine that lots of guys have.
Any guy mixing his first glass of creatine powder has hesitated. Is this the right move? His questions include:
Will creatine mess with my kidneys?
Researchers are constantly studying creatine—for effectiveness and safety. That’s why many trainers and health experts support the use of creatine: Studies indicate it’s safe.
“Creatine is one of the most-researched sports supplements out there,” Kerksick says. “And there’s no published literature to suggest it’s unsafe.”
Greenhaff has been studying creatine for about two decades, and says he never encounters the cramping that is sometimes reported.
“I’m not saying people don’t experience cramps, but I don’t believe it can be very common,” he says. “If there were any major adverse side effects, we would have seen them by now.”
But there have been anecdotal reports of kidney damage, heart problems, muscle cramps and pulls, dehydration, and diarrhea, in addition to other negative side effects. The key word here: anecdotal.
Some of these conditions can be caused by consuming too much of certain vitamins, says Tod Cooperman, M.D., president of ConsumerLab.com. “Too much vitamin C can cause diarrhea, and too much iron may lead to stomach problems,” he says.
To be safe, he recommends using creatine only if you are healthy and have no kidney problems. That’s because your kidneys excrete creatinine, a breakdown product of creatine.