PED stands for performance-enhancing drug. In bodybuilding, the term covers any substance used to increase muscle mass, reduce body fat, speed up recovery, or improve physical appearance beyond what training and nutrition alone can achieve. The category is broad, ranging from anabolic steroids and growth hormone to insulin, diuretics, and fat-burning agents. PEDs are a defining line in the sport: competitions are split between “tested” (natural) and “untested” divisions based entirely on whether athletes use them.
The Main Categories of PEDs
Bodybuilding PEDs fall into several distinct classes, each targeting a different part of physique development. Anabolic steroids are the most recognized, but serious competitors often use multiple categories simultaneously, a practice called “stacking.” The major groups include anabolic agents (steroids and related compounds), growth hormone and peptides, insulin, fat-loss agents, diuretics, and stimulants. Each serves a specific purpose at different phases of training and competition prep.
Anabolic Steroids
Anabolic-androgenic steroids are synthetic versions of testosterone and remain the most widely used PEDs in bodybuilding. They work through two pathways. The first is a slower, gene-level process: the steroid enters a muscle cell, binds to androgen receptors, and travels to the nucleus where it switches on genes responsible for protein building while switching off genes that break muscle down. This increases the rate at which your body turns dietary protein into actual muscle tissue.
The second pathway is faster, taking effect within minutes. Steroids activate signaling chains inside the cell that ramp up a key growth regulator called mTOR, the same pathway triggered by resistance training itself. When steroids and weight training are combined, mTOR activation is significantly greater than either one alone. Steroids also block the action of cortisol, the body’s primary stress hormone that breaks down muscle. This anti-catabolic effect means users recover faster and lose less muscle during intense dieting phases.
A landmark study published in the New England Journal of Medicine gave healthy men 600 mg of testosterone weekly for 10 weeks, roughly six times a typical medical replacement dose. The distinction between medical testosterone replacement and bodybuilding dosages is important. Therapeutic doses aim to restore normal hormone levels, while bodybuilding “cycles” push levels far above the natural range to force additional muscle growth.
SARMs
Selective androgen receptor modulators are a newer class of compounds that bind to the same receptors as steroids but are designed with a different chemical structure. The idea behind SARMs is that they could stimulate muscle growth while avoiding some of the unwanted effects in other tissues. In lab studies, much of their apparent selectivity comes from the fact that they aren’t broken down by the same enzymes that process traditional steroids, rather than from a fundamentally different mechanism. Whether this translates to meaningfully fewer side effects in real-world use remains unclear. SARMs are not approved for human use and are banned in tested competition, yet they’ve become widely available through online supplement retailers.
Growth Hormone and Insulin
Human growth hormone triggers the liver to produce a secondary hormone called IGF-1. Together, they stimulate amino acid and glucose uptake into muscle cells, preserve protein synthesis, and increase resting energy expenditure, meaning you burn more calories even at rest. In bodybuilding, growth hormone is valued for its ability to simultaneously support muscle fullness while promoting fat loss, a combination that’s extremely difficult to achieve naturally.
Insulin is one of the more dangerous PEDs in bodybuilding. It drives amino acids and glucose into muscle cells, theoretically enhancing the anabolic response to feeding and improving glycogen storage. Bodybuilders typically inject fast-acting insulin around workouts and immediately consume high-sugar foods to prevent blood sugar from crashing. The margin for error is slim. Too much insulin without enough carbohydrates causes severe hypoglycemia, which can lead to seizures, coma, or death within minutes. Beyond acute danger, chronic insulin misuse is linked to increased fat accumulation, worsened cholesterol profiles, liver stress (indicated by elevated liver enzyme ratios), and heightened systemic inflammation. When insulin is stacked with steroids and growth hormone, the combination raises the risk of cardiovascular events including heart attack and stroke.
Fat-Loss Agents
During contest preparation, bodybuilders need to reach extremely low body fat levels while preserving muscle. Two substances commonly used for this are clenbuterol and thyroid hormones.
Clenbuterol is a beta-2 receptor agonist originally developed for asthma. In a study of healthy young men, a single dose increased resting energy expenditure by 21% and fat burning by 39%, with no change in carbohydrate use. Beyond its fat-burning effects, clenbuterol may also have mild muscle-preserving properties, which explains its popularity during the cutting phase when calorie intake drops dramatically.
Synthetic thyroid hormone (T3) works differently. It directly speeds up metabolism by mimicking the hormone your thyroid gland produces naturally. Bodybuilders use it to accelerate fat loss in the final weeks before competition, though suppressing your own thyroid production carries the risk of rebound weight gain and metabolic sluggishness once the drug is stopped.
Diuretics and Contest Day Drugs
Diuretics are used in the final days before a bodybuilding show to shed water from beneath the skin, making muscles appear harder and more defined on stage. They work by forcing the kidneys to excrete more fluid. While this creates a dramatic visual effect, it also depletes electrolytes like potassium and sodium that are critical for heart rhythm. Sudden shifts in fluid balance have been linked to competitor deaths, making diuretics among the most acutely dangerous PEDs in the sport.
Cardiovascular and Long-Term Health Risks
The most serious health consequence of PED use in bodybuilding is cardiovascular damage. Data from the American Heart Association shows that anabolic steroid users have a ninefold increased incidence of cardiomyopathy compared to non-users. Among steroid users who developed cardiomyopathy, over 57% had a specific type involving abnormal thickening of the heart muscle. Imaging studies of active steroid users reveal increased heart mass, reduced pumping efficiency, and impaired ability of the heart to relax and fill with blood between beats. Former users showed persistent signs of subtle heart damage even after stopping.
Steroids also push cholesterol profiles in a dangerous direction, lowering protective HDL cholesterol while promoting plaque buildup in coronary arteries. Combined with the blood pressure increases caused by both steroids and the sheer body mass of competitive bodybuilders, the cardiovascular burden is substantial. Adding insulin and growth hormone to the mix worsens inflammation markers and further disrupts fat metabolism in ways that compound heart disease risk over time.
Tested vs. Untested Competition
The bodybuilding world is openly divided into drug-tested and untested federations. Organizations like the IFBB Pro League do not conduct rigorous drug testing, and PED use among competitors is an open reality. Natural federations take the opposite approach. The American Natural Bodybuilding Federation, for example, requires athletes to be completely drug-free for seven years before competing. Anabolic steroids, growth hormone, SARMs, and metabolic modulators all carry a seven-year ban period, while designer steroids carry a ten-year ban.
Testing in natural federations goes well beyond a simple urine sample. The ANBF uses a layered system that includes urinalysis for all winners and prize money recipients, randomized off-season testing, polygraph examinations, AI-based risk assessment of questionnaire responses, and in some cases voice analysis. Enhanced detection screening can identify substance use further back in time than standard panels. Winners of pro cards and prize money face mandatory urinalysis, and the federation can escalate to advanced laboratory methods like isotope ratio mass spectrometry testing, which can distinguish between naturally produced testosterone and synthetic versions.
The World Anti-Doping Agency classifies anabolic agents and peptide hormones as prohibited at all times, both in and out of competition. While WADA primarily governs Olympic sports, its prohibited list serves as the reference standard for most tested bodybuilding organizations.
Why PEDs Are So Prevalent in Bodybuilding
Bodybuilding is unique among sports in that the outcome is judged entirely on appearance. There’s no ball to throw farther or race to run faster. The goal is maximum muscle size, symmetry, and leanness, all evaluated visually on stage. PEDs directly improve every one of those criteria. Steroids build more muscle than training alone. Growth hormone and insulin create the extreme fullness and density seen in professional divisions. Fat-loss agents strip away the last layer of body fat. Diuretics create the paper-thin skin look that wins shows. Each class of PED maps directly to a judging criterion, which is why their use is so deeply embedded in the competitive side of the sport.
For recreational lifters who never plan to compete, PED use is still common. The desire for faster results, a more muscular physique, or the ability to recover from more frequent training drives use outside of competition. Surveys suggest that the majority of steroid users are non-competitive recreational bodybuilders, making the health implications relevant far beyond the stage.