For building muscle, low doses (anabolic) steroids are effective but only up to a certain point.
Dutch researchers have shown that giving bodybuilders 200 milligrams of Deca Durabolin a week (for 12 weeks) increased lean body weight by about 5 pounds and most of it was muscle. Studies performed by Dr. S. Bhasin have shown that taking low doses of steroids (such as 200-300 mg of Deca) only serves to replace the male’s natural testosterone production. As a note, the physician’s prescribing and administering those low doses you are referring to were for contraceptive purposes.
After a 12 week cycle, you will probably gain around 5 pounds of lean mass. However, your natural testosterone production will be screwed (at least temporarily). Therefore, you will only have two choices.
The first is to continue using higher doses that eventually turn into “year-long” cycles and experience the repercussions that long-term drug abuse carries. No bodybuilder does “just one cycle.”
The second choice is to go off the drug to restore your own retarded endocrine system and lose most (if not all) the gains you’ve made. This will occur simply because your natural testosterone production now resembles a 65-year-old female’s rather than a healthy young man. No drug will speed this restoration process.
Remember, there are always repercussions to steroid use. Don’t let anyone kid you that there are no side effects from steroid use at any dose – it’s just a matter of what you are prepared to live with.
These are the only options that arise from using a low-dose of anabolic steroids. Neither option is productive to longevity in the sport. I’m not a “goodie-two-shoes” here, but frankly, I don’t see the point of using low dose steroids, particularly now that there are supplementation and training strategies shown in research to produce similar results in muscle mass gains but without the unwanted side effects.
Source: Med Sci Sports Exercise