Supplements for strength: what works and what doesn't

The supplement industry generates over $50 billion per year. Most of it is built on marketing dressed up as science, flashy labels, and the hope that a powder or pill can shortcut the work.

Here’s the uncomfortable truth: the overwhelming majority of supplements do nothing meaningful for strength. A few actually work. As our nutrition guide for strength training makes clear, food and training are the foundation. Knowing which supplements are worth adding on top saves you hundreds of dollars a year and keeps you focused on what actually matters.

Tier 1: actually works

These supplements have strong, consistent evidence from multiple well-designed studies. They deliver measurable performance benefits for strength trainees.

Creatine monohydrate

Creatine is the single most researched and effective legal supplement for strength and power. Over 500 studies spanning three decades confirm it works. A 2003 meta-analysis by Branch found that creatine increased maximum strength by 8% and repetitions to failure by 14% compared to placebo.

It works by increasing phosphocreatine stores in your muscles, which helps regenerate ATP - your body’s immediate energy currency - during heavy sets. More ATP means better performance on those last critical reps of your 5x5 sets.

How to take it: 3-5g of creatine monohydrate daily. Any time of day. Mix in water. No loading phase required, no cycling needed. Buy the cheapest brand you can find.

Cost: Roughly $5-9 per month.

Side effects: 1-3kg of water weight gain (intracellular, not bloating). That’s it for healthy individuals.

For the full breakdown, read the complete creatine guide.

Caffeine

Caffeine is a proven ergogenic aid. It works by blocking adenosine receptors (reducing perceived fatigue) and increasing adrenaline output. The result: you feel more alert, more motivated, and can push slightly harder.

A 2010 meta-analysis in the Journal of Strength and Conditioning Research found that caffeine improved maximal strength by approximately 3-4% and muscular endurance by 6-7%.

How to take it: 3-6mg per kg of bodyweight, 30-60 minutes before training. For an 80kg person, that’s 240-480mg - roughly 2-4 cups of coffee.

Important caveats:

• Tolerance builds quickly. If you drink coffee all day, the performance boost diminishes
• Caffeine after 2-3pm can disrupt sleep, which undermines recovery
• More is not better. Above 6mg/kg, side effects (anxiety, heart palpitations, GI distress) outweigh benefits

Best sources: Black coffee, caffeine pills (cheap, precise dosing), or green tea. You don’t need a $40 pre-workout for caffeine.

Protein powder

Protein powder isn’t magic. It’s food in convenient form. A scoop of whey provides roughly 25g of highly bioavailable protein with minimal calories.

It belongs in Tier 1 not because it has special muscle-building properties, but because hitting your daily protein target consistently is critical, and protein powder makes that easier for many people.

When it’s useful:

• You struggle to eat 1.6-2.2g of protein per kg bodyweight from whole food
• You want a quick post-workout option
• You travel frequently and need portable protein

When it’s unnecessary:

• You already hit protein targets through meals
• You can easily eat chicken, eggs, fish, and dairy throughout the day

Which type: Whey concentrate is the best value for most people. Whey isolate if you’re lactose-intolerant. Plant-based blends (pea + rice) if you avoid dairy. Don’t overthink it.

Tier 2: some evidence, situational benefit

These supplements have research suggesting potential benefits, but the evidence is weaker, the effects are smaller, or they only help in specific situations.

Beta-alanine

Beta-alanine increases carnosine levels in muscles, which buffers hydrogen ions during high-rep or sustained efforts. It primarily improves endurance performance - sets lasting 60-240 seconds.

For a 5x5 program where sets are heavy and short (typically 15-30 seconds under load), beta-alanine’s benefit is minimal. It may help if you do higher-rep accessory work or conditioning alongside your main lifts.

Dose: 3-6g daily (split into smaller doses to reduce the harmless but annoying tingling sensation). Effects take 2-4 weeks of consistent use to appear.

Verdict: Skip it for pure strength training. Consider it if you also do conditioning or higher-volume hypertrophy work.

Citrulline

L-citrulline (or citrulline malate) is a precursor to nitric oxide, which may improve blood flow to working muscles. Some research shows modest improvements in rep performance and reduced soreness.

A 2010 study found that 8g of citrulline malate increased reps to failure on bench press by 19% compared to placebo. But this was a single study, and subsequent research has been mixed.

Dose: 6-8g of citrulline malate 30-60 minutes before training.

Verdict: Possibly helpful for training performance and recovery. Not essential. If you try it, give it 2-3 weeks and track your performance to see if you notice a difference.

Vitamin D

Vitamin D isn’t a performance supplement in the traditional sense. But deficiency is extremely common - studies estimate 40-50% of adults are deficient, especially those who work indoors, live at higher latitudes, or have darker skin.

Low vitamin D levels are associated with reduced muscle strength, impaired recovery, and compromised immune function. Correcting a deficiency can meaningfully improve all three.

How to know if you need it: Get a blood test. Optimal levels are 30-50 ng/mL (75-125 nmol/L). If you’re below 20 ng/mL, supplementation is strongly recommended.

Dose: 1,000-4,000 IU of vitamin D3 daily, taken with a meal containing fat (vitamin D is fat-soluble).

Verdict: Not a strength-booster for people with normal levels. Potentially significant for the many people who are deficient without knowing it.

Omega-3 fish oil

Fish oil (EPA and DHA) has anti-inflammatory properties and some evidence for improving muscle protein synthesis and reducing exercise-induced muscle soreness.

The strength-specific evidence is modest. But overall health benefits - cardiovascular, cognitive, joint - are well-supported. If you don’t eat fatty fish (salmon, mackerel, sardines) 2-3 times per week, fish oil is a reasonable addition.

Dose: 2-3g of combined EPA and DHA daily.

Verdict: More of a general health supplement than a strength-specific one. Worth considering for overall well-being.

Tier 3: waste of money

These supplements are heavily marketed but have little to no evidence for improving strength or muscle growth. Save your money.

BCAAs (branched-chain amino acids)

BCAAs - leucine, isoleucine, and valine - are three of the nine essential amino acids. They’re genuinely important for muscle building. The problem: they’re already in every complete protein source you eat.

If you consume adequate protein from food and/or whey, you’re already getting plenty of BCAAs. Adding more on top has been shown repeatedly to provide zero additional benefit.

A 2017 review in the Journal of the International Society of Sports Nutrition concluded that BCAAs alone don’t stimulate muscle protein synthesis any better than complete protein sources. You’re paying $25-40 for amino acids you already get from chicken breast.

The only scenario where BCAAs make sense: Training completely fasted with no protein for several hours before or after. Even then, whey protein would be a better and cheaper choice.

Testosterone boosters

The supplement industry loves implying that you can naturally boost testosterone with herbs and proprietary blends. Common ingredients include tribulus terrestris, fenugreek, ashwagandha, and D-aspartic acid.

The reality: none of these reliably increase testosterone to a degree that affects muscle growth. Some studies show small, statistically significant increases that are clinically meaningless - well within normal daily fluctuation.

If your testosterone is genuinely low, you need medical evaluation and potentially TRT (testosterone replacement therapy), not a $50 bottle of herbs. If your testosterone is normal, these products won’t push it higher in any meaningful way.

Fat burners

Most fat burners are caffeine combined with green tea extract, capsaicin, and other ingredients with marginal or no evidence for fat loss. You’re paying $30-50 for what’s essentially caffeine in fancy packaging.

Caffeine can slightly increase metabolic rate and fat oxidation. But the effect is small - roughly 50-100 extra calories burned per day. That’s a tablespoon of peanut butter. A caloric deficit through diet management is infinitely more effective than any fat burner.

If you want caffeine’s mild thermogenic effect, drink coffee. It costs 90% less.

Most pre-workouts

The pre-workout market is a masterclass in marketing. Bright labels, aggressive names, proprietary blends hiding actual ingredient amounts, and enormous markups.

Strip away the branding and most pre-workouts are: caffeine (the only ingredient that works for acute performance), beta-alanine (causes tingling so you “feel” something), citrulline (in doses too low to be effective in most products), and a bunch of underdosed or unproven extras.

A better pre-workout for a fraction of the cost:

• 200mg caffeine pill ($0.05)
• Optional: 5g creatine ($0.10, though timing doesn’t matter)

Total: $0.15 vs $1-2 per serving for a branded pre-workout.

Mass gainers

Mass gainers are protein powder mixed with large amounts of maltodextrin (a cheap carbohydrate). A typical serving has 50-80g of protein and 200-300g of carbs, totaling 1,000-1,200 calories.

You can get the same result for less money with a homemade shake: protein powder, oats, banana, peanut butter, and milk. Better ingredients, better macronutrient control, and significantly cheaper.

If you’re struggling to eat enough to support muscle growth, read the guide on bulking on 5x5 for practical calorie-increasing strategies.

How to actually spend your supplement budget

If you have $30-40 per month for supplements, here’s the evidence-based priority:

Step 1: creatine monohydrate ($5-9/month)

This is the single highest-return supplement investment. Non-negotiable if you’re serious about strength.

Step 2: protein powder if needed ($15-25/month)

Only if you can’t hit your protein target through food. One tub lasts most people 3-4 weeks.

Step 3: vitamin D if deficient ($3-5/month)

Get tested. If you’re below 30 ng/mL, supplement. If you’re fine, skip it.

Step 4: coffee ($0-10/month)

If you respond well to caffeine and train in a timeframe that won’t disrupt sleep, coffee before training is cheap and effective.

That’s it. Four items. Total monthly cost: $25-50. Everything else is optional at best and wasteful at worst.

The fundamentals matter more than any supplement

Here’s what actually drives your strength gains, in order of importance:

1. Consistent training with progressive overload
2. Adequate protein (1.6-2.2g per kg bodyweight)
3. Sufficient sleep (7-9 hours)
4. Overall nutrition (enough calories, balanced macros)
5. Supplements (creatine, maybe protein powder)

Notice where supplements fall. Dead last. They provide the smallest marginal return of anything on this list. A lifter who trains consistently, eats enough protein, and sleeps well but takes zero supplements will outperform someone who has a cabinet full of products but trains inconsistently and sleeps six hours a night.

Don’t spend $100/month on supplements while sleeping six hours and eating 80g of protein. Fix the basics. Then add creatine. That’s the entire supplement strategy for 95% of lifters.

Red flags when buying supplements

Watch out for these warning signs:

• Proprietary blends: If the label lists a blend without individual ingredient amounts, you have no idea what you’re actually getting. Avoid.
• Outrageous claims: “Gain 10 lbs of muscle in 30 days” or “boost testosterone 300%.” If it sounds too good to be true, it is.
• Before-and-after photos: These prove nothing about the supplement. Lighting, angles, pump, and months of training explain the difference.
• Celebrity endorsements: Athletes are paid to promote products. Their physique comes from genetics, training, and often other substances - not from the supplement they’re holding in the ad.
• “Clinically dosed” without citations: This phrase is meaningless unless they reference the actual study and match the dosing protocol used.

The bottom line

The supplement industry thrives on complexity. It wants you to believe that you need a dozen products, precisely timed, in specific combinations, or your training is suboptimal.

The evidence says otherwise. Creatine works. Caffeine works. Protein powder is useful if you need it. Everything else is either situational, marginal, or pure marketing.

Spend your money on good food, a gym membership, and creatine monohydrate. Spend your energy on showing up, training hard, and recovering properly. That’s where results actually come from. For the full breakdown of what to eat and how much, read our complete nutrition guide.

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