Five Possible Reasons for Taking Supplements or Drugs as Part of a Workout Regimen

People take supplements and performance-related substances as part of workout regimens for five main reasons: filling nutritional gaps that diet does not fully address, improving recovery time and reducing muscle damage, enhancing exercise performance and energy output, supporting specific body composition goals, and in some cases, using prescription or controlled substances for performance or medical reasons related to training. Not all of these categories carry the same evidence base or the same risk profile.

Most supplements have modest effects at best when nutrition and training fundamentals are not in place. The strongest evidence supports a short list of substances — primarily protein, creatine, and caffeine — while most others have limited proof of significant benefit.

1. Filling Nutritional Gaps That Diet Does Not Cover

The most straightforward reason to take supplements is to address genuine nutritional deficiencies or gaps that regular diet does not reliably fill. Many people who train regularly have increased nutritional needs that a typical diet may not meet consistently.

Protein supplements are the most widely used for this reason. Dietary protein intake recommendations for people who train at significant intensity are higher than general population guidelines, and meeting those targets through whole food alone can be inconvenient and expensive. Protein powders — whey, casein, plant-based blends — provide a convenient, calorie-efficient way to hit protein targets.

Vitamin D is commonly deficient in people who live in northern latitudes, work indoors, or avoid sun exposure. Vitamin D plays a role in muscle function, immune health, and bone density — all relevant to training. Deficiency is common enough that supplementation is frequently appropriate.

Magnesium and zinc are minerals involved in muscle contraction, recovery, and testosterone regulation. They are depleted through sweat and are sometimes insufficiently supplied by diet, particularly in people eating restricted diets or training at high volume.

Omega-3 fatty acids (fish oil) reduce systemic inflammation — relevant for training recovery — and are frequently under-consumed in diets that do not include regular fatty fish.

2. Improving Recovery Time and Reducing Muscle Damage

Training causes controlled muscle damage that, when followed by adequate recovery, produces strength and hypertrophy gains. Supplements in this category target the recovery process — reducing inflammation, supporting muscle protein synthesis, or replenishing depleted substrates.

Creatine monohydrate is the most evidence-supported non-stimulant supplement for training. It increases phosphocreatine stores in muscle, allowing more adenosine triphosphate (ATP) to be available during high-intensity exercise, which supports recovery between sets and may increase total training volume. The evidence base for creatine in terms of both efficacy and safety is among the strongest in sports nutrition.

Branched-chain amino acids (BCAAs) — leucine, isoleucine, and valine — are the amino acids most involved in muscle protein synthesis. While their benefit is less clear for people who already meet total protein targets, they are widely taken around training sessions to support recovery.

Beta-alanine buffers lactic acid accumulation during high-intensity exercise, reducing the fatigue that limits performance in short, intense efforts. It is best supported for endurance athletes and high-intensity interval training.

Tart cherry juice and turmeric are increasingly studied for their anti-inflammatory properties and relevance to recovery from training-induced muscle damage.

3. Enhancing Exercise Performance and Energy Output

A third category targets acute exercise performance — the quality, intensity, and duration of a single training session or competition.

Caffeine is the most consumed and best-researched ergogenic (performance-enhancing) substance in sports. It reduces perceived exertion, improves reaction time, increases endurance, and supports strength output. The evidence for caffeine’s performance benefits is robust across multiple exercise modalities. It is naturally occurring, found in coffee and tea, and available in concentrated supplement form.

Pre-workout supplements are typically caffeine-containing blends that may also include beta-alanine, nitric oxide precursors (like citrulline or arginine), and stimulants. They are widely used to increase training energy and focus. The evidence for specific blends is variable; caffeine’s contribution typically accounts for the majority of the perceivable effect.

Nitric oxide precursors (citrulline, arginine) are taken to support vasodilation — widening of blood vessels — which increases blood flow and oxygen delivery to muscles during training. Evidence is moderate and results are more pronounced in endurance training.

Carbohydrate supplementation — sports drinks, gels, and energy chews — is genuinely evidence-supported for endurance training lasting more than 60–90 minutes. They provide rapid glucose to sustain output when glycogen stores are depleting.

4. Supporting Body Composition Goals

Many people take supplements specifically to support fat loss, muscle gain, or the combination of both — often called body recomposition.

Thermogenic fat burners typically combine caffeine with other stimulants (green tea extract, synephrine, yohimbine) to increase metabolic rate and fat oxidation. The effects are real but modest — thermogenics produce measurable but not large fat loss effects when combined with caloric restriction and exercise.

Protein supplements serve double duty here: beyond nutritional support, adequate protein intake during fat loss is essential for preserving muscle mass while in a caloric deficit. The evidence for high protein intake during fat loss phases is strong.

Leucine and HMB (beta-hydroxy beta-methylbutyrate) are taken to support muscle protein synthesis and reduce muscle breakdown, particularly during cutting phases.

Meal replacement and diet products help people manage caloric intake by providing structured, portion-controlled nutrition that reduces ad hoc eating decisions — relevant for people whose primary goal is body composition change.

5. Prescription Medications, Controlled Substances, and Medical Use

The fifth category encompasses substances that go beyond over-the-counter supplementation. This includes both legitimate medical use and non-medical performance enhancement.

Testosterone replacement therapy (TRT) is medically prescribed for men with clinically low testosterone levels. When used legitimately, it has significant effects on muscle mass, recovery, energy, and libido — and many men who train are on medically supervised TRT.

Human growth hormone (HGH) is prescribed for specific medical conditions involving growth hormone deficiency. It is also used — outside medical indications — for body composition and anti-aging purposes, which is illegal in competitive sport and carries health risks.

Anabolic steroids are controlled substances in many countries, including the United States. While their performance-enhancing and muscle-building effects are real and well-documented, so are the health risks: cardiovascular effects, hormonal disruption, liver stress, and psychological effects. Their non-medical use is prohibited in sport and carries legal risk in many jurisdictions.

Prescription stimulants such as Adderall are sometimes used non-medically for training focus and energy. This is off-label use and carries both legal and health risks outside a prescribed clinical context.

The decision to supplement should be made with clarity about which category you are in and what the evidence says. A conversation with a registered dietitian or sports medicine physician is warranted before supplementing for medical gaps or taking anything beyond the well-studied basics.