Him, her and other
A lot of this was tested mostly in one sex. Here is who was actually in the studies, and what happened when both were.
Him
What was tested in men, and what that does and does not tell you.
Ligandrol (LGD-4033)
Its one trial was 76 healthy men, for 21 days. Lean mass went up. Their own testosterone went down, and it fell further as the amount went up.
We found no trial in women.
Tongkat ali
A review pooling 5 trials in men found higher total testosterone, including in men who started low.
Source: Review of 5 trials. Medicina, 2022.
Zinc
In 14 healthy, active men who already got enough zinc, a supplement raised zinc levels but not testosterone.
Source: Trial in 14 men. European Journal of Clinical Nutrition.
Boron
In 8 men with no comparison group, free testosterone rose after a week. A placebo-controlled trial in 19 bodybuilders found no effect.
Source: Study in 8 men; Trial in 19 bodybuilders.
Ecdysterone and turkesterone
A 10-week trial in 46 young men found more muscle and strength. An 8-week trial in 45 trained men found nothing.
Source: Trial in 46 men; Trial in 45 men.
Kisspeptin
In 6 healthy men, one dose roughly tripled the hormone LH within 30 minutes. In 32 men with low desire, one drip changed brain responses to sexual images.
Single lab sessions only.
Source: Kisspeptin-10 in healthy men. JCEM, 2011; Trial in men with low desire. JAMA Network Open, 2023.
PT-141 (bremelanotide)
Not approved for men. One trial of 342 men who had not responded to sildenafil used a nasal spray. About 34% were helped, against 9% on placebo.
Melanotan II
A 1996 pilot study gave it to 3 men for two weeks. Two got darker skin. They also had nausea and on-and-off erections.
Tirzepatide and the other weight-loss drugs
Here men are the thin file. A review of 30 years of obesity-drug trials found they signed up too few men. In a look back at 1,039 clinic patients on tirzepatide, men lost a smaller share of their weight than women.
Clinic records, not a head-to-head trial.
Source: Who was in obesity-drug trials. Lancet Diabetes and Endocrinology, 2024; Tirzepatide by sex, 1,039 patients. Obesity, 2026.
Sermorelin
In 19 adults aged 55 to 71, skin got thicker in both sexes. Lean mass rose in the men only.
Source: Trial in 19 older adults. JCEM, 1997.
Alpha-GPC
The attention and power trials were in young men: 20 in one, 48 in the other.
Her
What was tested in women, and where women's results came out different.
PT-141 (bremelanotide)
The one thing on this site approved for women only: low desire in women before menopause. Two trials in 1,267 women found a small but real improvement over placebo.
Source: Two trials in women. Obstetrics and Gynecology, 2019.
Tirzepatide and the other weight-loss drugs
In a look back at 1,039 clinic patients on tirzepatide, women lost a larger share of their body weight than men. A 2025 review also found women reported more nausea and vomiting on the newer weight-loss drugs.
Clinic records, not a head-to-head trial.
Source: Tirzepatide by sex, 1,039 patients. Obesity, 2026; Sex differences in obesity treatment. Current Psychiatry Reports, 2025.
Creatine
A 2021 review says women carry 70 to 80% lower creatine stores than men, and that creatine in women is understudied.
Rapamycin
In the one-year aging trial, lean mass and pain improved in women in one group. The trial still missed its main goal.
Source: Trial in healthy adults. Aging, 2025.
RAD-140
Its only human trial was 22 women with advanced breast cancer. It was a cancer study, not a muscle study.
Ostarine
One SARM trial that let women in: 120 healthy older men and women past menopause, for 12 weeks.
Source: Trial in 120 older adults. Journal of Cachexia, Sarcopenia and Muscle, 2011.
Kisspeptin
One trial tested it in women before menopause who had low desire. It measured brain responses during a single session, not day-to-day life.
Source: Trial in women with low desire. JAMA Network Open, 2022.
Collagen for skin
The skin trials are mostly women. A pooled look at 19 studies counted 1,125 people, and 95% were women.
Source: Review of 19 skin trials. International Journal of Dermatology, 2021.
MK-677
The two-year trial had 65 healthy adults aged 60 to 81: men, and women both on and off hormone therapy.
Sermorelin
In the 19-adult study, 10 were women. Skin got thicker in both sexes. Lean mass rose in the men only.
Source: Trial in 19 older adults. JCEM, 1997.
Tested in men only
The trials we cite for these were in men: ligandrol, melanotan II, tongkat ali, zinc, boron, ecdysterone and alpha-GPC. For women that is a blank page, not a no. The Him tab has the sources.
Other
There is no such thing as other…
…on the sign-up sheet, or inside a cell.
Nothing here is about your heart or your soul. Those are yours. This is only what the lab notebook says.
The sign-up sheet has two boxes
The US trial registry lists who can join a study as Female, Male or All. There is no fourth box.
Source: ClinicalTrials.gov allowed values.
Every cell has a sex
Not our line. It was a headline finding of a 2001 Institute of Medicine report on why sex matters in health research.
It hangs on one gene
In 1990 scientists found the gene, in the stretch of the Y chromosome that male development needs. They named it SRY.
Source: Nature, 1990.
Red blood cells sit this one out
They throw out their nucleus before they start work. No nucleus, no chromosomes, no opinion.
Source: Experimental Hematology, 2021.
Mothers keep souvenirs
Cells from a son have been found in his mother's blood up to 27 years after the birth. In one autopsy study, 37 of 59 women had male DNA in the brain.
Source: PNAS, 1996; PLoS One, 2012.
Men misplace the Y
In a study of 205,011 men, about 1 in 5 had blood cells that had lost their Y chromosome.
Source: Nature, 2019.
The real exceptions
About 1 in 650 boys is born with an extra X. About 1 in 2,000 girls is born with a single X. Some people have XY chromosomes and a body that developed as female. Rare, real, and not a punchline.
Source: Klinefelter syndrome. MedlinePlus Genetics; Turner syndrome. MedlinePlus Genetics; Androgen insensitivity syndrome. MedlinePlus Genetics.
Who you are is yours to say. What a study measured is all we report. If your body or your hormones do not fit the usual pattern, a doctor who knows your labs beats any chart on this site.
Why two buckets
The rule used to be: leave women out
In 1977 an FDA policy recommended keeping women who could become pregnant out of early drug trials. Including women in NIH-funded research only became law in 1993.
Source: History of women in clinical research. NIH Office of Research on Women's Health.
Same amount, different blood level
One analysis found 86 drugs where women given the same amount as men ended up with more drug in the blood, for longer.
Source: Sex differences in pharmacokinetics. Handbook of Experimental Pharmacology, 2023.
Side effects land on women more
Women have bad drug reactions nearly twice as often as men, a 2020 review found.
Source: Biology of Sex Differences, 2020.
Testosterone is not close
After puberty, men's blood testosterone runs more than 15 times higher than women's. SARMs and testosterone boosters all act on that system, so this page keeps the results apart.
Source: Endocrine Reviews, 2018.
Sometimes it flips
Obesity-drug trials signed up too many women and too few men, a review of 30 years of trials found.
Keep going
We show what studies found. We never tell you what to take. Last checked November 12, 2026.