In short
- Strength training itself doesn’t cause gynecomastia. Certain products do.
- Anabolic steroids are a major cause: excess testosterone is converted into oestrogen, and stopping them shuts down the testicles.
- Prohormones, SARMs and contaminated supplements bought online can also cause it.
- Whey and creatine do not cause gynecomastia.
- A lump that appears under the nipple during or after taking such products should be shown to a doctor quickly: the more recent it is, the easier it is to treat.
In gyms, gynecomastia has a nickname: “gyno”. It is common there, and for a specific reason. It isn’t strength training that causes it, it is certain products used to speed up results. Here is how it works, what is responsible, what isn’t, and what to do if it affects you.
Why steroids cause gynecomastia
Most anabolic steroids are testosterone or testosterone derivatives. You might think an excess of male hormone would protect against gynecomastia. It is the opposite, for two reasons.
1. Aromatisation. The aromatase enzyme, abundant in fat tissue, converts some testosterone into oestradiol, the main oestrogen. The more testosterone you add, the more oestrogen you make. Beyond a certain point, the breast gland is stimulated.
2. The testicles shut down. The brain detects the excess hormones and switches off its signal to the testicles. When the products are stopped, natural testosterone takes weeks or months to restart, while oestrogens stored in fat are still there. The balance tips heavily towards oestrogen: a high-risk period.
Some products also act in other ways, such as through prolactin or progesterone. The hormone hCG, misused by some, directly stimulates oestrogen production by the testicles.
The products involved
| Product | Risk of gynecomastia | Comment |
|---|---|---|
| Anabolic steroids (testosterone and derivatives) | High | A major cause in athletes |
| Prohormones | High | Precursors converted into active hormones |
| Misused hCG | High | Stimulates oestrogen production |
| SARMs | Possible | Suppress testosterone; unapproved products, uncertain contents |
| “Testosterone boosters” | Low, unless contaminated | Often ineffective; risk of undeclared substances |
| Dubious fat burners | Variable | Contents sometimes don’t match the label |
| Whey, casein, plant proteins | None | No hormonal effect |
| Creatine | None known | A well-studied supplement |
| Dietary soy | None of note | No proven effect on male hormones |
“Natural” supplements: the contamination trap
The vast majority of supplements sold for bodybuilding carry no hormonal risk. But repeated testing, in Europe and elsewhere, has found supplements contaminated with undeclared steroids or prohormones. This mostly concerns products promising spectacular gains and those sold on poorly regulated websites. A few rules:
- choose established brands sold by reputable retailers;
- be wary of claims such as “steroid effect without steroids” or “hormone booster”;
- keep the packaging: if a problem appears, it helps the doctor.
What is safe
- Strength training itself, at any intensity.
- Whey and other quality protein powders.
- Creatine, one of the most studied supplements.
- A high-protein diet, including meat, eggs, dairy or soy.
“Fake gyno” in gym-goers
Not every lifter whose chest changes has gynecomastia. Two situations are common:
- Well-developed pecs but a soft lower chest: often leftover fat, which goes during a cut. See losing chest fat.
- Puffy nipples: a small disc of gland, sometimes present since puberty, which muscle growth makes more visible.
The pinch test under the areola helps tell them apart. See gynecomastia or chest fat.
What to do if a lump appears
- Don’t let it drag on. Recent gynecomastia, often tender, is the most likely to shrink. After about a year, the tissue becomes fibrous and only surgery removes it.
- See a doctor and be honest about what you have taken. They are bound by medical confidentiality. Without that information, they can neither guide you nor interpret your hormone tests correctly.
- Don’t improvise treatment with anti-oestrogens bought online: using them without medical supervision exposes you to side effects and can mask a problem.
- Get your hormone recovery checked after stopping: persistent hypogonadism (long-term low testosterone) can be treated, but it has to be diagnosed.
In the UK, drug services and many needle and syringe programmes offer confidential, non-judgemental support to people using steroids, including health checks. Your GP can also refer you to an endocrinologist.
For treatment options: treatment without surgery and surgery.
Building your chest without products
An athletic physique without gynecomastia comes down to:
- a progressive programme over months and years;
- enough protein (around 1.6 g per kilo per day) and calories suited to your goal;
- sleep;
- patience, because the products promise to compress years into weeks, at a cost that isn’t limited to your chest.
In the meantime, a compression top lets you train without self-consciousness.
Your questions
Does whey protein make men grow breasts?
Can creatine cause gynecomastia?
Can steroid-induced gynecomastia go away?
Are natural testosterone boosters dangerous?
Do SARMs cause gynecomastia?
Sources
- Braunstein GD. Gynecomastia. N Engl J Med 2007 (anabolic steroids and aromatisation)
- MSD Manual — Gynecomastia: medicines and substances involved
- NHS — Anabolic steroid misuse
- Kreider RB et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. J Int Soc Sports Nutr 2017
