Evidence-Based Supplements for Muscle Growth

The supplement industry is worth billions, and most of it is marketing. But a small number of supplements have strong scientific evidence behind them. Here is an honest, brand-neutral ranking based on published research.

How We Ranked These Supplements

We used three criteria:

1. Strength of evidence - how many high-quality studies support the claim?
2. Effect size - how meaningful is the benefit?
3. Safety - is it safe for long-term use?

Tier 1: Strong Evidence - These Actually Work

1. Creatine Monohydrate

Creatine is the single most effective legal supplement for muscle growth and strength.

• How it works: Increases phosphocreatine stores in muscle, allowing more work during high-intensity sets
• Effect: 8% increase in strength, 14% increase in power output on average (Rawson & Volek, 2003)
• Dose: 3–5g daily
• Safety: Extensively studied, no adverse effects in healthy adults (Kreider et al., 2017, JISSN)

Creatine works for both men and women and at all training levels. For a complete guide, see our creatine article.

2. Protein Powder

Protein supplementation increases muscle gains when total daily protein is sufficient.

• How it works: Provides amino acids for muscle protein synthesis
• Effect: Increased lean mass and strength with resistance training (Morton et al., 2018, BJSM)
• Dose: 1–2 scoops daily (25–50g) to reach your daily protein target
• Best types: Whey isolate for post-workout, casein for before bed

Important: protein powder only helps if your total daily intake is sufficient. If you already eat 0.7+ g/lb (1.6+ g/kg) per day from food, adding a shake will not produce extra muscle gains. For powder comparisons, see our protein powder guide.

3. Caffeine

Caffeine is an ergogenic aid that improves workout performance.

• How it works: Blocks adenosine receptors, reducing perceived effort and fatigue
• Effect: Improves strength by 2–7% and endurance by 2–4% (Grgic et al., 2020, BJSM)
• Dose: 1.4–2.7mg per pound of body weight, 30–60 minutes before training (200–400mg for most people)
• Safety: Safe at moderate doses; avoid after early afternoon to protect sleep

Caffeine does not build muscle directly, but by improving training performance, it allows you to do more work - which drives muscle growth over time.

Tier 2: Moderate Evidence - May Help

4. Beta-Alanine

• How it works: Increases carnosine levels in muscle, buffering acid during high-rep sets
• Effect: Improves performance in exercises lasting 60–240 seconds (higher rep sets, supersets). Modest effect on lean mass in some studies (Hobson et al., 2012, Amino Acids)
• Dose: 3–5g daily (causes harmless tingling at higher single doses)
• Verdict: Useful if you do high-volume training. Less impactful for low-rep strength work.

5. HMB (Beta-Hydroxy Beta-Methylbutyrate)

• How it works: A metabolite of leucine that may reduce muscle protein breakdown
• Effect: Most beneficial for beginners or during periods of muscle loss (illness, immobilisation, extreme calorie deficit). Limited additional benefit for trained lifters eating enough protein (Wilson et al., 2013, JISSN)
• Dose: 3g daily
• Verdict: Potentially useful during aggressive cuts or for older adults. Not necessary for most trainees.

6. Vitamin D

• How it works: Supports testosterone production, bone health, and immune function
• Effect: Deficiency (common in northern latitudes) impairs muscle function. Supplementation to adequate levels restores normal function but does not provide supraphysiological benefits (Chiang et al., 2017)
• Dose: 1,000–4,000 IU daily (get blood levels tested if possible)
• Verdict: Important to correct a deficiency. Not a muscle builder per se.

Tier 3: Weak Evidence - Probably Not Worth It

7. BCAAs (Branched-Chain Amino Acids)

BCAAs (leucine, isoleucine, valine) were once widely recommended. However, modern research shows they are unnecessary if you eat enough total protein. A systematic review found no benefit of BCAAs over adequate total protein intake (Wolfe, 2017, JISSN). For more detail, see our article on amino acid supplements.

8. Testosterone Boosters (Herbal)

Products containing tribulus, fenugreek, D-aspartic acid, and ashwagandha are marketed as natural testosterone boosters. The evidence is weak:

• Most studies show no meaningful increase in testosterone in healthy young men
• Any effects tend to be small and inconsistent
• They cannot replicate the effects of actual hormonal therapies

Save your money.

9. Glutamine

Once a popular bodybuilding supplement, glutamine has been shown to have no additional benefit for muscle growth or recovery in well-fed individuals (Gleeson, 2008). Your body produces enough glutamine, and high-protein foods provide plenty more.

The Honest Supplement Stack

If you want maximum results with minimum waste, here is what the evidence supports:

Total: roughly $50–85/month. That is it. Everything else is optional at best.

The Bottom Line

The vast majority of muscle growth comes from training and nutrition - specifically, eating enough protein and progressively overloading in the gym. The only supplements with strong evidence are creatine, protein powder, and caffeine. Everything else is either situational or overhyped. Spend your money on good food first, and track your protein with Protein Pal.