Gym supplements: what actually works (and what's marketing)

The supplement industry is worth 200 billion dollars a year. 99% of what they sell does NOT work, or works so little you'd never notice. But a handful of supplements have solid scientific evidence and can add 5-15% to your results — if the basics (nutrition, sleep, training) are in order.

In this guide I'll tell you exactly what to buy, how to dose it, when to take it, and what instead is money thrown away. No discounts, no sponsorships.

Rule number 1: supplements come after the basics

If you don't eat enough, don't sleep enough and don't train in a structured way, no supplement in the world will compensate. Supplements are the last 5-10% — when the other 90-95% are already in order. For the base program, see our muscle mass workout plan.

That said, here's the complete list.

Tier 1 — They work: buy them

Creatine monohydrate

The single most studied supplement in history. Over 1000 studies, proven effect on:

• +5-15% max strength on 1RM
• +1-2 kg lean mass in 8-12 weeks
• Improved recovery between sets
• Cognitive performance in memory tasks

Dosing: 3-5 g/day, every day, at any time. Accumulates in muscle in 3-4 weeks.

NO loading (20 g for 5 days): recent studies show same final effect without digestive stress.

Cost: €15-25 per 500 g (6-12 months of use). Quality: Creapure® or other pure micronised creatine.

Side effects: +1-2 kg of intramuscular water retention (not fat). No negative kidney effects documented in healthy subjects (Kreider 2017).

Whey protein (or plant protein)

Protein powders are NOT magic. They're just a convenient way to reach the 1.6-2.2 g/kg total daily protein target. If you already hit it with food, skip.

When they're useful:

• Post-workout (fast absorption)
• Breakfast if you have no time
• Travel
• High protein target (160+ g/day) hard with food only

Dosing: 25-40 g per scoop, 1-3 times a day depending on meals.

Types:

• Whey concentrate: 70-80% protein, €30/kg. Standard.
• Whey isolate: 85-90% protein, low lactose. €40/kg. For intolerants.
• Casein: slow, good pre-sleep. €30/kg.
• Plant (pea, soy, rice): valid alternative for vegans. Mix for complete AA profile.

Vitamin D3

60-80% of European populations are deficient or insufficient in vitamin D. Effects of deficiency:

• Low testosterone
• Reduced strength and mass
• Compromised immune system
• Depressed mood

Dosing: 2000-4000 IU/day (October-March in Italy, year-round in the north). Better with fatty meal for absorption.

Ideal: get the 25(OH)D test. Target 30-50 ng/ml. If under 20, dose 5000 IU/day for 2 months then maintenance.

Cost: €8-15 for 100 tablets (3+ months).

Caffeine

The most effective ergogenic for strength, power and endurance performance.

• +3-7% strength (Grgic 2018 meta-analysis)
• +10% endurance
• Better focus and effort perception
• Slight DOMS reduction

Dosing: 3-6 mg/kg bodyweight, 30-60 min before training (75 kg = 225-450 mg).

Sources:

• Espresso: ~80 mg
• Filter coffee: 100-120 mg per cup
• Anhydrous caffeine (tablets): 100-200 mg, precise dosing
• Commercial pre-workouts: 150-300 mg (+ lots of other often-useless stuff)

Warning: tolerance develops in 2-3 weeks. Cycle or increase dose. Not over 400 mg/day total (anxiety, compromised sleep).

Tier 2 — They work in specific cases

Omega-3 (EPA + DHA)

Useful if you eat little fish (<2 times/week). Evidence on:

• Inflammation reduction
• Cardiovascular health
• Possible positive effect on protein synthesis in elderly

Dosing: 2-3 g/day of combined EPA+DHA. Cost: €15-25/month.

Beta-alanine

Effect on anaerobic endurance (30-90 sec sets, e.g. crossfit, HIIT, cycling).

Dosing: 3-5 g/day split in 2-3 doses (side effect: harmless tingling). Cost: €15/2 months.

Multivitamin

Useful as "insurance policy" if diet has holes. Doesn't replace fruit and vegetables.

Dosing: 1/day of a multi with reasonable levels (no megadoses). €15/month.

Magnesium

Useful if you sleep poorly or have cramps. Bisglycinate or citrate form (not oxide, terrible absorption).

Dosing: 200-400 mg before bed. €10/month.

Ashwagandha

Reduces cortisol and perceived stress. Useful if life is very stressful. Moderate evidence.

Dosing: 300-600 mg standardised extract (5% withanolides), 1-2 times/day. €15-25/month.

Tier 3 — Hype, don't buy

Isolated BCAAs

Branched-chain amino acids (leucine, isoleucine, valine) are found IN ABUNDANCE in any meal with complete proteins. Taking them isolated:

• Doesn't accelerate protein synthesis if you already have enough protein
• Studies show ZERO advantage vs whey
• Costs 4-5 times more per gram of leucine

Verdict: useless. Take whey if needed.

"Mass 4000" gainers

Powders with 2000+ kcal per scoop: 80% maltodextrin sugars + 20% poor proteins. Same result eating oats, bananas and whey at a fraction of cost and 10x superior nutritional quality.

Verdict: marketing for those who don't want to cook.

Pre-workout with 30 ingredients

The effective formula is simple: caffeine + beta-alanine + creatine. The rest (agmatine, citrulline DL-malate, sodium nitrate, vitargo, YK-11, unicorn powder) either has sub-therapeutic dosing or doesn't work.

Verdict: buy the ingredients that matter individually.

Fat burners / thermogenics

Combinations of caffeine + various extracts. The slimming effect is 95% from caffeine. The rest is theatre. "Targeted fat burning" does NOT exist (fat is lost systemically, not locally).

Verdict: drink black coffee, save €30/month.

Natural testosterone boosters

Tribulus, fenugreek, maca, DAA. Zero confirmed effects on testosterone in healthy men (Balestrino 2023 meta-analysis). If testosterone is low, see an endocrinologist, not a pharmacy.

Verdict: don't work.

Glutamine

Conditionally essential amino acid. Studies on healthy athletes: no effect on recovery, mass, strength or immunity.

Verdict: not needed.

Evidence-based stack example

A typical intermediate athlete (male, 75 kg, 4 workouts/week):

Compared to a "premium" €150/month stack with pre-workout, BCAAs, testo booster and expensive multivitamin: same or better effect for a fifth of the cost.

When to talk to a doctor

Before starting any supplement, evaluate base tests if:

• You've never done blood work
• You have symptoms (chronic fatigue, cramps, low mood)
• You're over 40
• You have pre-existing conditions (hypertension, diabetes, thyroid)

Useful tests: 25(OH)D, ferritin, B12, total+free testosterone (men), thyroid (TSH, fT4).

Conclusion

Supplements are 5% of results. Don't confuse "works a little" with "works a lot". The hierarchy is clear:

1. Nutrition (80% of the result)
2. Structured training (10%)
3. Recovery and sleep (5%)
4. Right supplements (5%)

If you want to invest in something that multiplies results, it's not the new "miracle" powder. It's an online PT who calibrates everything above based on your data. Try Athleex free for 14 days.

Spend less on supplements, more on real food and serious training. It's math.