You may have seen an athlete before and thought “there’s no way they’re that muscular, they must be on steroids.” In some cases, you may be correct – steroid use has swept through competitive athletics and bodybuilding over the past few decades, despite being illegal and banned. But what exactly are steroids and are they that bad for you?

Steroids are a broad family of molecules that can cause a variety of effects depending on the type and where they bind in the body.

There are two main types of steroids used in drugs today: corticosteroids and anabolic steroids. Commonly used in medicine, corticosteroids are one of our best tools for fighting inflammation and helping with infection. These drugs are synthetic forms of the natural hormone cortisol, which acts as the ‘fight or flight’ hormone in the body and regulates an array of processes in the body, from metabolism to the immune system.

However, if you are looking to build muscle, corticosteroids are not the right type of steroid. Anabolic steroids (also known as anabolic-androgenic steroids) are a different type of drug and illegal in most countries without a written prescription from a pharmacist. These drugs mimic the sex hormone testosterone and are well-known for being misused by some athletes to gain an edge over their competitors.

So how do anabolic steroids help people gain so much muscle so fast? Ted-Ed recently uploaded a brilliant summary on steroids — watch it below.

How do steroids affect your body? Credit: Ted-Ed

Testosterone is the primary sex hormone in males and controls the development of male reproductive tissues, including the testes. Testosterone also boosts the production of proteins that form muscle and increases bone density. Synthetic anabolic-androgenic steroids are derivatives of testosterone and elicit similar effects on the body.

As suggested by their name, anabolic-androgenic steroids bind to receptors within the cell called androgen receptors. The complex formed by the receptor and steroid enters the nucleus, where they interact with DNA to increase the activity of certain genes – particularly ones that are involved in male puberty and protein synthesis. These genes make the cells produce more proteins than they usually would.

The extra proteins produced form the building blocks of muscle, and with increased protein production there is increased muscle growth. This is called anabolism. Anabolic steroids also speed up how your body breaks down complex molecules into simpler molecules, called catabolism, which provides energy for muscle cells. If this process is faster, producing the necessary energy for working out takes less time.

So not only do you have more muscle, you need less rest between workouts – pretty useful if you’re an athlete. While they sound like a muscle-building miracle, anabolic steroids can have long-lasting effects on the bodies of those that misuse them.

Side-effects of anabolic steroid misuse vary for men and women. Men may experience a reduction in sperm count, infertility, enlarged breasts (gynecomastia), and increased risk of prostate cancer, whilst women may experience an increase in body hair growth, loss of breast tissue, issues with their menstrual cycle, and a deepened voice.

Anabolic steroids also put men and women at risk for far more serious concerns. Misuse has been linked to a higher risk of heart attack, liver and kidney failure, blood clotting, and high cholesterol. Use in adolescence is particularly bad as an increase in bone density too early can result in growth defects and may also have cognitive consequences, including decreased attention and increased impulsivity (commonly known as 'roid rage').

These are just the symptoms scientists are aware of. So whilst steroids sound like a quick-fix, these drugs could have massive implications on your health and should never be used recreationally.