Supplementation with creatine monohydrate at a dosage of 3–5 grams per day increases intramuscular creatine and phosphocreatine stores by 20–40%, which results in enhanced strength, power, and lean mass gains during resistance training without altering fat mass.

Study: The effects of pre versus post workout supplementation of creatine monohydrate on body composition and strength

This study gave people 5 grams of creatine daily while they worked out and found they got stronger and gained muscle without losing or gaining fat — just like the claim says.

Study: Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show?

This study looked at lots of research on creatine and found that taking 3–5 grams a day helps muscles store more energy, makes you stronger and more muscular during workouts, and doesn’t make you gain fat — and it’s safe.

Study: Clinical pharmacology of the dietary supplement creatine monohydrate.

This study says taking creatine powder (3–5g/day) helps muscles store more energy, making you stronger and better at lifting weights, and doesn’t make you gain fat—exactly what the claim says.

Study: International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine

This study says taking 3–5 grams of creatine daily helps muscles store more energy, making you stronger and better at workouts without making you gain fat—and it’s safe to take long-term.