Creatine is best known as a supplement used by gym-goers and athletes hoping to improve strength, power and muscle growth.

New research suggests it may also help middle-aged adults gain lean tissue even when they do not take part in a formal exercise programme.

The study, led by researchers at Texas A&M University published in Journal of the International Society of Sports Nutrition, followed adults aged 45 to 65 over 12 weeks. Participants who took creatine but remained sedentary gained an average of about 2.4 lb, or just over 1 kg, of lean tissue. Those who combined creatine with supervised training gained around 3 lb, or 1.4 kg.

The difference may appear modest. Yet it could be meaningful for adults in midlife, when gradual losses in muscle mass and strength become more common. Maintaining muscle is closely linked with mobility, metabolic health, physical independence and resilience in later life.

The findings do not suggest that creatine can replace exercise.

Resistance training remains the most reliable way to build strength, preserve muscle and improve long-term physical function. However, the trial adds to evidence that creatine may be a useful support for people who are inactive, beginning an exercise routine or at risk of losing lean mass.

“Participants who took creatine but remained sedentary gained an average of about 2.4 lb, or just over 1 kg, of lean tissue. Those who combined creatine with supervised training gained around 3 lb, or 1.4 kg”

Creatine is a naturally occurring compound that helps the body produce energy. Most is stored in skeletal muscle, where it supports the rapid recycling of energy during demanding activity. Muscles rely on a molecule called adenosine triphosphate, or ATP, for immediate energy. Creatine helps replenish ATP during short bursts of effort such as lifting, climbing stairs or sprinting.

The body makes creatine from amino acids, including arginine, glycine and methionine. It is also found naturally in meat and fish. People who eat little or no animal food often have lower stores of creatine in their muscles, although their bodies can still produce some.

Creatine monohydrate is the form most commonly used in supplements and the one with the strongest research base. It has been studied in athletes, older adults, people recovering from injury and individuals with certain neurological or muscular conditions. Most research has focused on creatine alongside resistance exercise. The new trial explored whether it may have benefits without structured training.

Participants in the study were not meeting physical-activity recommendations before joining. They were given the option of taking part in a supervised exercise programme. Thirty-eight participants chose the training programme, while 26 remained sedentary for the duration of the study.

Those in the exercise programme attended three supervised sessions each week. They were also asked to walk 10,000 steps on non-training days. Participants who did not choose the training programme did not complete these sessions.

Researchers then randomly allocated people in both groups to receive either creatine monohydrate or a placebo twice daily. The study was blinded, meaning participants did not know which product they were receiving.

All participants were advised to follow a diet based on American Heart Association guidance. The plan provided about 55% of calories from carbohydrate, 15% from protein and 30% from fat. It was designed to create a daily calorie deficit of approximately 300 to 500 kcal.

Researchers assessed body composition, strength, cognitive performance and several blood markers at the beginning of the trial, after six weeks and again at 12 weeks.

The sedentary participants taking creatine gained roughly 2.4 lb of lean tissue by the end of the study. They also improved their bench press and leg press strength upon testing. This result has attracted attention because it suggests creatine could affect lean mass and physical capability beyond the gym.

There are important caveats. Lean tissue is not the same as muscle tissue. It includes muscle, water, organs, connective tissue and other non-fat components of the body. Creatine often increases water content inside muscle cells, particularly in the early stages of use. This can contribute to increases seen on body-composition scans.

The researchers used dual-energy X-ray absorptiometry, known as DXA, to estimate lean tissue. DXA is widely used in clinical and research settings, but it does not directly measure individual muscle fibres or distinguish fully between muscle growth and changes in body water.

The improved strength scores are therefore an important part of the picture. They indicate that participants did not simply register a change on a scan. They also became stronger in the tested movements. Still, the study cannot establish exactly why this happened.

One possible explanation is that creatine improves the energy available to muscle. Everyday activities might then feel less tiring or more manageable. A person may walk more, take stairs more often, carry shopping more easily or move with greater confidence. Over several weeks, these small changes could lead to meaningful extra activity.

That explanation remains a hypothesis. The study did not directly measure every movement participants made outside their supervised sessions. Researchers would need to track daily activity more closely in future trials.

Participants who took creatine and completed the exercise programme experienced the greatest overall improvements. They gained around 3 lb of lean tissue, improved bench press and leg press strength, and increased their time to exhaustion during exercise testing.

This group also lost body fat mass and reduced body-fat percentage. Creatine does not directly burn fat. It is not a weight-loss medicine. Its possible benefit is more indirect, it may help people train with greater capacity, preserve fat-free mass during calorie restriction or maintain strength while losing weight.

In the exercise group receiving placebo, researchers found little change in lean tissue over 12 weeks. This contrast suggests that creatine may have made a contribution. It does not mean that every person who takes creatine will gain muscle, lose fat or become stronger without other changes.

The trial has several limitations. Participants chose whether to join the exercise programme. Those who opted for training may have been more motivated, healthier or more inclined to follow dietary and activity advice. This self-selection makes direct comparisons between the sedentary and exercise groups less certain.

The study was also relatively small. Small trials can identify promising findings, though they cannot provide definitive answers. Larger research studies are needed to determine whether the same effects occur across different ages, sexes, health conditions and diets.

Dietary adherence is another factor. Participants were given a calorie-restricted dietary plan, but following a prescribed diet in day-to-day life can be difficult. Protein intake is especially important when studying lean tissue.

The trial diet contained a moderate amount of protein, around 15% of total calories. It remains unclear whether sedentary adults taking creatine might see greater benefits if they also consumed more protein.

The researchers also observed potentially favourable changes in measures related to blood fats, glucose regulation and cognitive performance among creatine users. These results should be treated as preliminary. The study was not large enough to prove that creatine improves brain health, reduces diabetes risk or protects against heart disease.

For healthy adults, creatine monohydrate is generally considered safe when used appropriately. The most common effect is a small increase in body weight, often caused by water being held within muscle. Some people experience bloating, nausea or stomach discomfort, particularly if they take a large dose at once.

People with kidney disease, those who are pregnant or breastfeeding, and anyone taking medication that could affect kidney function should consult a healthcare professional before using creatine. It is also sensible to select supplements from reputable brands that use independent quality testing.

The broader lesson remains straightforward. Regular physical activity, resistance exercise, adequate protein, sleep and a balanced diet are the foundations of healthy ageing. Supplements can support these habits. They cannot replace them.

For adults who are currently inactive, the study offers a cautious but encouraging message. Creatine may provide modest help in maintaining or increasing lean tissue while someone works towards becoming more active. It could also prove valuable for those who cannot exercise fully because of temporary injury, illness or reduced mobility.

More rigorous research is needed before creatine can be recommended specifically as a muscle-preserving tool for sedentary adults. Scientists will need to confirm whether the extra lean tissue represents genuine muscle growth, identify the people most likely to benefit, and examine how the effects change over longer periods.

For now, creatine appears best viewed as a useful adjunct. It may support strength and lean mass, especially when paired with resistance training. The new findings suggest its role could be broader than previously thought, but exercise remains the central strategy for protecting muscle and function through midlife and beyond.