Creatine has been a staple supplement in the fitness world for decades, sitting in gym bags alongside lifting straps and protein shakers. For many athletes and gym-goers, it’s considered one of the most reliable ways to boost performance in the weight room.
Now, one online fitness coach has given followers a simple visual demonstration of what the supplement can do — sharing a striking before-and-after look at his physique after using creatine consistently.
Online coach and bodybuilder Cillian Domican posted a video to TikTok showing how his body changed during a 30-day period of taking creatine. The clip compared two training clips filmed under similar conditions, highlighting differences in his muscle size and definition.
The contrast was noticeable.
In the second clip, Domican appeared both fuller and more defined through his shoulders and upper body. Viewers quickly picked up on the changes, with many pointing out the same areas that seemed to have developed.
“It worked,” one person wrote. Another added: “Side delts got bigger”.
Domican also joined the discussion in the comments, explaining that the supplement had allowed him to push harder in training. He revealed that he could “push more” after starting the supplement. Check out the clip below:
Cillian would later go on to share another before-and-after video showcasing the impact of taking creatine over a one-month period – and, once again, the results speak for themselves:
To ensure the comparison was fair, he also clarified that he worked out beforehand in both clips to achieve a “pump” — the temporary swelling muscles experience during exercise when blood flow increases.
Creatine itself isn’t a new or experimental supplement. In fact, it’s one of the most researched compounds in sports science and has long been used by athletes seeking improvements in strength and training performance.
The compound occurs naturally in the body and also exists in many common foods.
According to information from the Cleveland Clinic, creatine is produced naturally in the liver, kidneys and pancreas. From there, it is transported around the body to support energy production. The organisation explains that these organs deliver “about 95% of the creatine to your skeletal muscles to use during physical activity. The rest goes to your heart, brain and other tissues.”
Although some creatine is obtained through diet — particularly from protein-rich foods like meat and dairy — many athletes choose to supplement in order to increase the amount available to their muscles. Creatine supplements are widely available and commonly come in powder form, though they can also appear as tablets, liquids or even energy bars.
While the supplement itself does not directly build muscle tissue, it supports the body’s ability to produce quick bursts of energy during high-intensity activity. This can allow athletes to train harder, lift heavier weights, or perform more repetitions — factors that can indirectly contribute to muscle growth over time.
Domican has also shared other clips on his TikTok page exploring the difference creatine made to his physique.
In one video, he compared how he looked at 90 kilograms both on and off the supplement. While taking creatine, he appeared noticeably leaner and bulkier, with followers commenting that his muscles looked fuller. Another clip showed him wearing the same T-shirt during different periods of supplementation. While taking creatine, Domican said he was “filling his t-shirt”, whereas the same shirt appeared looser when he was not using the supplement.
While most conversations around creatine centre on strength and physique changes, scientists are also beginning to explore a very different area of potential benefits: the brain.
Creatine plays a key role in how the body generates cellular energy, which is why it has long been associated with high-intensity exercise. But because the compound is also present in the brain, researchers are now investigating whether it might influence cognitive function as well.
A recent study published in Scientific Reports looked at whether creatine could help people maintain mental performance after sleep deprivation. Research scientist Ali Gordjinejad from the Forschungszentrum Jülich led an experiment involving 15 participants who were given either creatine or a placebo at 6:00PM.
Their reaction times, memory and thinking speed were then tested every two-and-a-half hours throughout the night until 9:00AM the next morning.
The results surprised the researchers.
Participants who had taken creatine processed information faster than those who received the placebo, suggesting the supplement may help the brain cope with the strain of sleep deprivation.
As Gordjinejad explained, per BBC News: “It was assumed that the body’s uptake of creatine cells is marginal, therefore it wouldn’t work for only one night of sleep deprivation – until we did our study.”
However, the experiment also used a much higher dose than most experts recommend. Participants were given 35 grams — roughly ten times the commonly suggested daily intake. Most guidance suggests a daily dose of around three to five grams of creatine monohydrate. Larger amounts can sometimes cause stomach discomfort and may pose risks for individuals with kidney problems.
Other researchers are also examining the compound’s potential role in brain health. According to Scott Forbes, PhD, there is growing evidence suggesting that the compound may have a number of neurological benefits.
He told Medical News Today that creatine may “reduce inflammation and oxidative stress, which can benefit the brain”. Forbes also noted that “creatine may reduce the risk of depression and anxiety, be neuroprotective against brain injury, and help support brain health and development”.
At the same time, some researchers believe long-standing guidelines around creatine intake may need revisiting.
For years, the widely accepted recommendation in the fitness world has been a simple five grams per day — a scoop size familiar to most gym-goers.
But a narrative review published in the Advanced Exercise and Health Science journal suggests that amount may only be optimised for muscle performance, rather than the broader health benefits scientists are beginning to explore.
Dr Darren Candow, who authored the review, believes individuals seeking wider physiological benefits may require a higher intake. “Five grams per day is a great start, but it’s optimised for skeletal muscle only. If you want full-body benefits – bone, brain, immune, anti-inflammatory – you’ll need more,” Dr. Candow suggested.
Candow added that dosage should instead be calculated relative to body weight, saying: “You should take at least 0.1g of creatine for every kilogram you weigh, each day, to experience the best skeletal muscle benefits.”
For someone weighing 70 kilograms, that formula would equate to around seven grams daily — already more than the traditional five-gram scoop that dominates supplement shelves.
The review also pointed to potential links between creatine intake and bone health. “The lowest effective dose for bone strength was 8g daily; 5g didn’t move the needle. If you want to preserve skeletal strength, especially around the hips, higher daily doses are required – and always in combination with weight-bearing exercise,” Candow said.
While creatine itself doesn’t directly build muscle, it supports the body’s ability to produce rapid energy during demanding exercise, allowing athletes and lifters to train harder and potentially see better results over time.
At the same time, scientists are now beginning to understand that its influence may reach beyond the gym floor.
From cognitive performance during sleep deprivation to potential long-term neurological benefits, researchers are slowly uncovering a much broader picture of how creatine functions inside the human body.
As with any supplement, experts advise speaking with a healthcare professional before adding it to your routine.
But for many gym-goers, creatine remains a staple — and stories like Domican’s are a reminder of why it has maintained that reputation for so long.
Featured image credit: TikTok/@cilliandomican (screenshot)
