Science

The science of creatine

Inside of your body.
Creatine is a natural compound your body already produces, synthesized from three amino acids (arginine, glycine, and methionine) in the liver, kidneys, and pancreas. Once made, it's stored primarily in your muscles and brain, where it plays a direct role in regenerating ATP, which is the energy your cells run on during physical and mental effort.
Outside of your body.
Your body doesn't rely solely on what it produces. A meaningful portion of your creatine also comes from food, mainly red meat and fish, which are by far the most concentrated dietary sources available through a normal diet.
Those following a plant-based diet get little to none from food, making the gap even larger.
The Problem
Here's the problem: even combined, what your body makes and what food provides isn't enough to fully saturate your creatine stores. Most people operate at roughly 60-80% of their maximum capacity. That gap is exactly what supplementation is built to close, and why it matters.

Notes

ATP is your body's fuel, every cell runs on it.

How it works

Creatine helps your body produce more ATP, which gives your cells more energy to work with.

In practice, that means more usable energy for movement, performance, and mental clarity, so you can go longer before fatigue hits.

ATP Creatine Cycle

Energy store

ATP is ready to be used the moment you move or think.

Energy spent

Every step, every thought, every contraction, energy is spent.

ATP becomes ADP

ATP releases energy and loses a phosphate. No longer fully charged.

Creatine donates phosphate

Creatine, stored as phosphocreatine, turns ADP back to ATP

↩ cycle repeats

Notes

Phosphate is the energy trigger. When ATP releases a phosphate group, your cells get a burst of energy.

The benefits

Every benefit of creatine traces back to the same root: more ATP available, faster, at the cellular level.

Physical performance

Strength gain
Build more muscle
Faster recovery
Increased explosive power

Cognitive performance

Better memory
More mental resilience
Faster processing

Longevity and Health

Anti-sarcopenia (muscle loss)
Stronger bones & reduced fracture risk
Reduced inflammation
Long-term brain health

First signals

From day one, your muscles begin to store more creatine. You might notice a small boost of explosive energy during your workouts. The first sign that your phosphocreatine reserves are building up.

Full effect

By week two to four weeks, your muscles are fully saturated. This is where you really start to feel it: more power, less fatigue at the end of your sessions, and faster recovery between sets. Research also shows improvements in memory and cognitive speed, making creatine as much a brain supplement as a body one.

New baseline

With your stores fully saturated, your body adapts to training harder. Muscle gains become more visible, soreness decreases, and you can train more frequently. Mentally, you'll notice sharper clarity and faster reaction times not just in the gym, but in everyday life too.

Consistency wins

This is where consistency pays off. Long-term studies show sustained improvements in memory and cognitive speed. The longer you stay consistent, the more you benefit. Physically, lean muscle is consolidated, performance keeps improving, and your body becomes more efficient with energy.

FAQ

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Is creatine a steroid?

No. Creatine is a natural compound produced by your body and found in food. It has no connection to anabolic steroids and it's one of the most studied and best tolerated supplements in the world.

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Does creatine cause water retention?

Slightly, yes, but inside the muscle cells, not under the skin. It's intracellular retention that contributes to performance and recovery, not visible swelling.

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Is creatine bad for the kidneys?

In healthy individuals, no. Decades of research have found no negative effects on kidney function at normal doses.

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Is creatine only for bodybuilders?

No. Creatine benefits anyone who wants more cellular energy : endurance athletes, recreational sportsmen, professionals who want to perform better mentally, and even older people to prevent muscle loss.

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Is creatine a steroid?

No. Creatine is a natural compound produced by your body and found in food. It has no connection to anabolic steroids and it's one of the most studied and best tolerated supplements in the world.

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Does creatine cause water retention?

Slightly, yes, but inside the muscle cells, not under the skin. It's intracellular retention that contributes to performance and recovery, not visible swelling.

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Is creatine bad for the kidneys?

In healthy individuals, no. Decades of research have found no negative effects on kidney function at normal doses.

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Is creatine only for bodybuilders?

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Is creatine in gummies as effective as creatine in powder form?

Yes, as long as the dose of creatine monohydrate is the same. The delivery method does not affect absorption, what matters is the daily dose.

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When will I feel the effects?

You can feel a slight energy boost from the very first days. The most noticeable effects appear between 2 and 4 weeks, when your muscles are fully saturated.

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Does this also work for cognitive performance?

Yes. The brain uses as much ATP as muscles. Studies show improvements in memory, processing speed, and mental resilience, especially during periods of stress or sleep deprivation.

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Does creatine cause hair loss?

No. That's one of the most widespread myths about creatine. The science is clear : creatine does not cause hair loss.

Source Library

The following information is based on published clinical research and is provided for educational purposes only. Flex does not claim to diagnose, treat, or cure any medical condition.

-Cleveland Clinic, 2025 — Creatine: What It Does, Benefits, Supplements & Safety

Bonilla et al., 2021 — Metabolic Basis of Creatine in Health and Disease: A Bioinformatics-Assisted Review

Wallimann et al., 2000Creatine and Creatinine Metabolism — Physiological Reviews

Kreider et al., 2017ISSN Position Stand: Safety and Efficacy of Creatine Supplementation

-Forbes et al., 2023 — Creatine Supplementation and Endurance Performance: Surges and Sprints to Win the Race

-Zhang et al., 2025 — Effects of Creatine Supplementation on Muscle Strength Gains: A Meta-Analysis and Systematic Review

-Bogdanis et al., 2022 — Effects of Oral Creatine Supplementation on Power Output during Repeated Treadmill Sprinting

-Xu et al., 2024 — The Effects of Creatine Supplementation on Cognitive Function in Adults: A Systematic Review and Meta-Analysis

-Prokopidis et al., 2023 — Effects of Creatine Supplementation on Memory in Healthy Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

-Gordji-Nejad et al., 2024 — Single Dose Creatine Improves Cognitive Performance and Induces Changes in Cerebral High Energy Phosphates During Sleep Deprivation

-Candow et al., 2019 — Effectiveness of Creatine Supplementation on Aging Muscle and Bone: Focus on Falls Prevention and Inflammation

-Chilibeck et al., 2015 — Effects of Creatine and Resistance Training on Bone Health in Postmenopausal Women

Gualano et al., 2016 — Creatine Supplementation in the Aging Population: Effects on Skeletal Muscle, Bone and Brain