AAS are one of the major PEDs used by athletes. They have been shown to increase muscle mass, which leads to increased speed and power output ( 5 ). Athletes using AAS can experience strength gains of 5–20% and weight gains of 4.5–11 pounds (2–5 kg), which may be due to an increase in lean body mass ( 5 ).

Some athletes take a form of steroids — known as anabolic-androgenic steroids or just anabolic steroids — to increase their muscle mass and strength. The main anabolic steroid hormone produced by your body is testosterone. Testosterone has two main effects on your body: Anabolic effects promote muscle building.

“Anabolic steroids produce a permanent increase in users’ capacity for muscle development. In keeping with this, studies show that mice given testosterone acquire new myonuclei that persist long after the steroid use ends.”

The received wisdom is that testosterone must be injected weekly for at least 10 weeks. Yet sports scientist Robert Weatherby of Southern Cross University in Lismore, New South Wales, Australia, who conducted the study, found the biggest increase in performance came after just three weeks.

Accidentally taking too many steroid tablets is unlikely to be harmful if it’s a one-off. Speak to your doctor or a pharmacist if you’re worried. Taking too many steroid tablets over a long period can make you more likely to get side effects.

Muscle mass Despite causing some water weight gain, research has found that creatine can be an effective supplement for increasing endurance and strength. Over time, you may see an increase in your muscle strength and size. Increased muscle mass will also tip the scale upward.

Some research shows that taking creatine daily does not improve lung function. However, other research shows that taking creatine may improve lung function or exercise capacity. Heart failure and fluid build up in the body (congestive heart failure or CHF).

Addition of creatine increases ATP levels in sperm and enhances sperm motility in vitro.

Research proves that a creatine loading phase can maximize your muscle stores within one week or less (2). This strategy involves taking 20 grams of creatine daily for 5–7 days to saturate your muscles rapidly, followed by 2–10 grams daily to maintain high levels (2, 6 ).

The International Society of Sports Nutrition recently found no scientific evidence that short- or long-term use of creatine monohydrate causes any harmful effects on otherwise healthy individuals.

Studies have found that taking a creatine supplement does not harm kidney function in healthy people. Creatine may cause bloating or stomach discomfort if you take too much at one time.

Creatine is the most effective supplement for increasing muscle mass and strength ( 1 ). It is a fundamental supplement in the bodybuilding and fitness communities ( 2 ). Research shows supplementing with creatine can double your strength and lean muscle gains when compared to training alone ( 3 ).