Former mining communities in south Wales have the worst levels of steroid abuse in the UK, research seen by the BBC has shown.
Steroid use to build muscles can cause impotence
A survey by the University of Glamorgan found as many as seven out of 10 people using gyms in the region take drugs to help their training.
More inactive lifestyles mean people are turning to steroids to get the shape they want, the study author says.
The research is unveiled on the BBC Radio Wales programme Eye on Wales.
Professor Bruce Davies carried out the research in gyms dedicated to heavy lifting in the south Wales valleys area, and says the findings replicate those of studies carried out in other parts of Wales.
He said: "We found by going into big lifting gyms that 70% of the attendants were using anabolic steroids.
"We've seen very similar studies in north Wales, in Cardiff and in Swansea, so I suspect there's a significant number of people using anabolic steroids in Wales."
Side-effects of the drugs can include baldness, impotence, developing milk-producing breasts in men and acne, and in misuse of anabolic steroids can cause heart and liver failure.
Professor Davies believes use has risen in former mining areas because of social changes.
"Gone are the days when you could get admiration by going down a mine -you didn't have to prove anything," he said.
"Sadly those days are gone and now people are seeking other ways to gain admiration.
"When you think about it these days, most people are semi-debauched, we're not a very active society so the only way to acquire the muscles these people want is to weight train using anabolic steroids."
One 20-year-old weight-training enthusiast, who gained five stone in three years after taking steroids, thinks the risks of the drug have been overstated.
"It's down to the individual - if your diet's good and your training's good you should be fine," he said.
"Ok, something could go wrong inside but that could happen to a normal person walking down the street. A lot [of the risks] are just word of mouth and I think a lot of things are exaggerated totally out of perspective."
Possession and use of steroids is not illegal, provided it is a "medicinal form", but dealing steroids is.
Katy Swaine, head of legal services at drug charity Release, thinks there is some ambiguity about what constitutes a medicinal form of the drug.
"The law [on steroids] still remains in a slightly unclear state and could certainly do with clarification now," she said.
The research, entitled Steroid and Prescription Medicine - Abuses in the Recreational Gym user - a regional study, questioned 210 people at 100 heaving lifting gyms in the former Mid Glamorgan county area in 2005.
Eye on Wales is broadcast on BBC Radio Wales on Monday 3 July at 1800 BST.