The supplement aisle is mostly noise. A handful of products have strong evidence; the rest range from "maybe useful in a specific case" to "expensive urine". This guide cuts through the marketing and focuses on what is actually worth your money for general fitness.
The Evidence Table
| Supplement | Dose | Effect | Evidence |
|---|---|---|---|
| Whey / plant protein | 20-40 g per serving | Hits daily protein, recovery | Strong |
| Creatine monohydrate | 3-5 g/day | Strength, power, lean mass | Strong |
| Vitamin D3 | 1,000-2,000 IU/day | Bone, immune, possibly performance | Strong if deficient |
| Omega-3 (EPA/DHA) | 1-3 g/day combined | Cardiometabolic, anti-inflammatory | Moderate |
| Caffeine | 3-6 mg/kg pre-training | Endurance, strength, focus | Strong |
| Beta-alanine | 3-6 g/day | 1-4 min high-intensity work | Moderate |
How to Think About Supplements
- Supplements are leverage on top of training, nutrition, sleep — never a substitute.
- If a product can't tell you its dose per serving, skip it.
- Look for third-party tested brands (Informed Sport, NSF Certified for Sport).
- Stack effects don't multiply — most claimed synergies are marketing.
- "Natural" doesn't mean "safe" — some herbs have real drug interactions.
- Trial one supplement at a time so you know what's actually doing the work.
A Sensible Stack
- Protein powder if you struggle to hit daily protein from food.
- Creatine monohydrate, 3-5 g/day, taken any time.
- Vitamin D3 (1,000-2,000 IU) in autumn/winter or if indoors all day.
- Fish oil for omega-3 if you eat little oily fish.
- Caffeine 30-60 min pre-workout when you need a lift.
- Nothing else unless a specific medical or sport need justifies it.
Red Flags in Marketing
Beware of "proprietary blends" (no dose disclosure), before/after pictures with vague captions, "as seen on TV", celebrity endorsements without studies, and anything promising rapid fat loss without diet change. A clean label, transparent dosing, batch testing, and boring scientific claims are the markers of a serious product.
Timing & Dosing That Actually Matters
For most evidence-backed supplements, total daily dose matters far more than timing. Creatine works through saturation, so 3–5 g any time of day is fine — there is no need to "load" unless you want full stores within a week. Protein is about hitting your daily target (roughly 1.6–2.2 g/kg for active people); spreading it across 3–4 meals helps but the daily total dominates. Caffeine is the main exception where timing counts: take it 30–60 minutes before training and keep it at least 8–10 hours before bed to protect sleep. Vitamin D3 is fat-soluble, so take it with a meal that contains some fat.
Safety & Sourcing
Supplements are loosely regulated in most countries — the manufacturer, not a government agency, is usually responsible for safety and label accuracy before sale. That makes third-party testing the single most useful filter: look for NSF Certified for Sport or Informed Sport seals, which verify contents and screen for contaminants. If you take prescription medication, are pregnant or breastfeeding, or have a kidney or liver condition, check with a doctor or pharmacist before starting anything — some "natural" ingredients have real drug interactions. For balanced, non-commercial overviews of individual ingredients, the NIH Office of Dietary Supplements fact sheets are a reliable reference. This guide is educational and not medical advice.
Get Your Macros First
Before any supplement, lock in protein and calories. FitCalc's macro calculator helps.
Macro Calculator →