Muscle
The boring stuff has the best proof. The exciting stuff mostly does not.
The short version
Two cheap things have strong human proof: creatine and extra protein, both alongside lifting. Growth hormone adds lean weight on the scale but did not make people stronger. The peptides people stack for muscle have almost no human proof at all.
What has proof
Creatine + lifting
A review pooling 22 trials in 721 older adults found about 1.4 kg more lean tissue with creatine than without, plus small strength gains. A 2026 review of 39 trials in young men found the body-composition gain only showed up in people who were actually training.
no training, no gain
Protein + lifting
A review of 49 trials in 1,863 adults compared lifting with extra protein to lifting alone. With extra protein, people could lift about 2.5 kg more for one rep. They also gained about 0.3 kg more lean weight. Past about 1.6 g of protein per kg of bodyweight a day, more protein added nothing further. The effect was smaller in older people and bigger in people already trained.
a real effect, and a small one
Growth hormone itself
A review covered 27 groups, 303 fit young people in all, who were given growth hormone. They gained about 2.1 kg of lean weight. They did not get stronger. They could not exercise any harder. Lactate during exercise ran higher in 2 of 3 studies that measured it. Swelling and tiredness were more common.
heavier on the scale, not stronger
MK-677 (a pill, not a peptide)
In a 2-year trial of 65 healthy adults aged 60 to 81, it added about 1.1 kg of fat-free mass and 2.7 kg of body weight. Strength and function did not change. Appetite rose, fasting blood sugar rose, and insulin sensitivity fell.
Gym lore, checked
Gym lore is what people say, not what we recommend. Each one is followed by what studies in people show. Stories are real experiences. They are not proof.
"ipamorelin makes you hungry"
Half right, and untested in people. Ipamorelin works on the same receptor the hunger hormone ghrelin uses. In mice it raised food intake and body fat. We found no human study that measured hunger on ipamorelin. The related pill MK-677 did raise appetite in a two-year human trial, which is probably where the belief comes from.
"no carbs around your shot, sugar kills the GH spike"
A real lab finding. No proof it changes results. In small studies, a sugar drink shortly beforehand cut the growth hormone response roughly in half. But the same sugar load a few hours later pushed growth hormone up instead, so the effect flips over time. We found no study of the real question. Does food timing change how much muscle or fat a person ends up with?
"CJC-1295 and ipamorelin together build more muscle"
Not tested, as far as we can find. We found no study that gave people both and measured their muscle. A 2026 review of these peptides found two thirds of all the research was in animals, and the human studies were few and mostly uncontrolled.
"insulin builds muscle, just keep sugar on hand"
We never write how-tos. This one shows why. In a survey of 41 non-diabetic lifters who used insulin, more than half had their blood sugar crash, and one lost consciousness. A separate case report describes a 30-year-old bodybuilder found in a coma who needed glucose put straight into his veins in hospital. A blood sugar crash can happen while you are asleep or driving, and sugar tablets do not help someone who is already unconscious.
this is the one that puts people in comas
What we don't know
- Whether any growth hormone peptide builds real muscle in people. No trial has shown it.
- What any of these do over years. The human studies run weeks.
- What is actually in a vial bought online.
Sources
- Creatine and resistance training in older adults, review of 22 trials. Open Access Journal of Sports Medicine, 2017. Journal page
- Creatine in young men, review of 39 trials. Frontiers in Nutrition, 2026. Journal page
- Protein supplementation and resistance training, review of 49 trials. British Journal of Sports Medicine, 2018. Journal page
- Growth hormone and athletic performance, systematic review. Annals of Internal Medicine, 2008. Journal page
- MK-677 in older adults, 2-year trial. Annals of Internal Medicine, 2008. Journal page
- Ipamorelin after bowel surgery, trial in 114 patients. International Journal of Colorectal Disease, 2015. Journal page
- Ipamorelin, food intake and fat in mice. Biochemical and Biophysical Research Communications, 2001. Journal page
- Glucose and the growth hormone response to GHRH. Journal of Clinical Endocrinology and Metabolism, 1997. Journal page
- Glucose and the response to a GH-releasing peptide. European Journal of Endocrinology, 1997. Journal page
- Peptides and musculoskeletal outcomes, 2026 scoping review. American Journal of Sports Medicine. Journal page
- Insulin use in non-diabetic lifters, survey of 41. Current Sports Medicine Reports, 2012. Journal page
- Bodybuilder in hypoglycemic coma, case report. Journal of Emergency Medicine, 2019. Journal page
Studies found on PubMed. Last checked November 12, 2026. Information only. Not medical advice.