Everything You Need to Know About Creatine

Creatine is not a foreign substance to the body. Our bodies produce it every day from the amino acids arginine, glycine, and methionine, primarily in the liver and kidneys. We also obtain small amounts from our diet, mainly from meat (raw beef contains approximately 0.3–0.5 g per 100 g). Heat treatment reduces the amount of creatine in meat.

In recent years, creatine has become one of the most widely used supplements, not only among athletes. As is often the case, several myths and frequently asked questions have also emerged around creatine. So let's clear things up once and for all.

Why Should Athletes Supplement with Creatine?

Every athlete who takes their performance seriously will sooner or later face the question: "Which supplements are best for me? Do I even need any?" One of the most thoroughly researched and effective supplements is creatine monohydrate.

The primary source of energy for every muscle contraction is ATP (adenosine triphosphate). It acts as the body's universal energy currency, without which no movement would be possible.

However, the muscles' ATP stores are very limited and only provide enough energy for the first few seconds of maximal effort. Once ATP is depleted, the cells need to regenerate it immediately.

To maintain high-intensity exercise, the body relies on the phosphocreatine system. So, how does this energy conversion actually work?

When a muscle contracts, an ATP molecule releases one phosphate group, which releases energy. The result is a "depleted" ADP molecule (adenosine diphosphate, which has two phosphate groups instead of three). Rather than waiting for ATP to be regenerated through slower energy systems, the body uses phosphocreatine stored in the muscles.

Phosphocreatine breaks down into creatine and a phosphate group. That phosphate group is then transferred to ADP, converting it back into ATP. The muscle can therefore quickly regenerate its energy supply and continue working at maximal intensity.

By supplementing with creatine over the long term, you increase your muscle stores of phosphocreatine.

The Truth About Initial Weight Gain

When you start taking creatine, you will probably notice one thing after a few days: the number on the scale may jump up slightly. Many people panic at this point, thinking they are gaining fat. The reality, however, is quite different.

The initial increase in body weight when taking creatine is generally the result of increased muscle hydration, not an increase in body fat.

Early studies on creatine supplementation, particularly those involving a loading phase (around 20 g per day), did show a slight increase in water retention during the first few days, but there is a specific reason for this. Creatine is an osmotically active substance, meaning that as creatine accumulates inside muscle cells, it draws water into the cells as well. This significantly increases cellular hydration and muscle cell volume.

Because of this, many athletes worry that they will look bloated or "waterlogged." However, longer-term studies indicate that creatine does not cause significant water accumulation outside the cells or lead to edema.

While conventional water retention, for example due to hormonal changes or a higher dietary sodium intake, occurs primarily in the subcutaneous tissues and can create a soft, puffy appearance, creatine works differently. When creatine increases total body water, the increase is predominantly intracellular, directly within the muscles. As a result, the muscles may appear fuller and more solid.

Debunking the Biggest Myth: Does Creatine Damage the Kidneys?

One of the biggest concerns surrounding creatine supplementation is the fear that it may damage the kidneys. Let's look at what the scientific evidence actually tells us.

Kidney damage resulting from long-term supplementation at recommended daily doses has not been demonstrated in healthy individuals. So where did this concern come from? It largely revolves around how kidney function is measured and how the body processes creatinine.

Every day, approximately 1–2% of the total creatine stored in muscle is spontaneously converted into creatinine, a waste product of metabolism. Creatinine enters the bloodstream, where it is filtered by the kidney glomeruli and subsequently excreted in the urine.

Serum creatinine concentration is commonly used as a clinical marker of glomerular filtration rate (GFR).

Why Doesn't a Higher Creatinine Level Necessarily Mean Kidney Damage?

If you perform resistance training, have a higher amount of muscle mass, or consume more meat, your blood creatinine level may naturally be slightly elevated. Laboratory results may therefore show higher values, but this does not automatically mean that kidney function is impaired.

Much of the concern about kidney damage likely originated from individual case reports. One example is the following:

• A case report described a young man with an existing kidney condition, focal segmental glomerulosclerosis. He began taking creatine at a loading dose of 15 g per day for one week, followed by 2 g per day. After starting supplementation, his serum creatinine levels increased, which, based on standard calculations, raised concerns about impaired kidney function. After discontinuing creatine, his creatinine levels returned to normal.

A scientific review by Gualano et al. examined similar case reports. It found that the cases were affected by important confounding factors: patients were taking immunosuppressive medications, had a history of kidney disease, were using extremely high doses of creatine, or were also using anabolic steroids.

If you take creatine and your creatinine level comes back slightly above the reference range, there is no need to panic. In cases where the results are unclear, kidney function can also be assessed using other markers, such as cystatin C, a blood marker that is not significantly affected by muscle mass or creatine intake.

Important: People with a pre-existing, diagnosed kidney disease should consult their healthcare professional before starting any supplementation.

Is Creatine Beneficial for Older Adults?

As our bodies gradually age, we naturally begin to lose muscle mass. This process is known as sarcopenia. It is associated with a higher risk of falls and fractures, as well as reduced independence. Resistance training and creatine supplementation are therefore receiving increasing attention as potential strategies for preventing or slowing muscle loss.

Creatine Alone Is Not Enough to Protect Muscle

Studies show that creatine alone does not significantly increase muscle strength or muscle mass. The short-term increase in body weight that sometimes occurs after starting creatine is primarily caused by increased water retention, as creatine is osmotically active, rather than an increase in muscle tissue.

Long-term studies, including studies in postmenopausal women, have confirmed that without exercise, creatine does not prevent muscle loss.

Creatine supplementation alone may modestly improve certain measures of muscle fatigue, but meaningful improvements in muscle growth and physical function require more than supplementation alone.

Combining Creatine with Resistance Training

When creatine supplementation is combined with regular resistance training, however, the picture is different. Creatine can enhance the effects of resistance training on muscle growth in both younger and older adults.

Creatine may allow for greater training volume and intensity, which can positively influence muscle protein synthesis and growth-related signaling while potentially reducing inflammation and oxidative stress. The result can be greater strength, improved ability to perform everyday activities, and delayed fatigue.

Research Is Also Looking at Bone Health and Osteoporosis

Beyond muscle, researchers are also investigating the potential effects of creatine on bone health and age-related bone loss.

• In older men, combining creatine with resistance training for 10–12 weeks increased bone mineral content in the upper limbs and reduced markers of bone breakdown.
• In postmenopausal women, one year of creatine supplementation combined with exercise helped reduce the rate of bone mineral loss in the hip region.
• However, the same principle applies here: without exercise, such as during two years of creatine supplementation without resistance training, positive effects on bone structure have not been consistently demonstrated.

Research also suggests that creatine may have some interesting effects on the brain. More on that soon in a new article.