How to Read a Supplement Label
Five checks, ten minutes, any bottle on the shelf. We'll use PhenQ's label (rev 1022, all 13 ingredients disclosed) as the worked example — because it is one of the rare labels complete enough to check.
Start with the serving size, always
Every error in supplement comparison starts here.
Labels state amounts per serving, not per capsule — and the two differ by however many capsules the serving contains. PhenQ’s daily serving is two capsules, so every per-capsule figure on the label doubles: 75 mg of caffeine per capsule is 150 mg/day in practice. Marketers know most shoppers skim per-capsule numbers; the serving line is where the real exposure lives.
The same math runs backwards. A “600 mg proprietary blend per serving” split across six ingredients averages 100 mg each — before accounting for cheap ingredients padded to the front of the list.
The proprietary-blend trap
The single most important thing on any label is what it refuses to tell you.
What a blend hides
A blend lists its ingredients in descending order but only publishes the total. You can confirm a formula “contains” a headline ingredient while having no idea whether its dose is the 300 mg the studies used or the 12 mg that fits the marketing story.
Why disclosure matters
PhenQ publishes every dose — 13 ingredients, exact amounts — which is why this site could build a dose-vs-evidence table for it at all. Most competitor labels make that check impossible by design. Transparency is not proof of effectiveness, but opacity is proof of nothing.
Read %DV as nutrition, not weight loss
Daily Value percentages answer a different question than the one you're asking.
Percent Daily Value tells you how a serving contributes to normal nutritional needs. On PhenQ’s label, iodine sits at 100% DV and copper at 111% DV — genuinely useful if you are checking for nutrient coverage, and a good sign the micronutrient panel is dosed like a multivitamin, not like a drug.
But %DV says nothing about effectiveness for weight management, because no DV exists for that. A label can be 100% honest about nutrition and still carry ingredients whose weight-loss doses are nowhere near the research. Both things are true on most labels at once — including, in places, this one.
The dose-vs-study check, and the caffeine math
The two habits that separate reviewers from shoppers.
Compare each dose to its studies
Find the ingredient’s key trial or meta-analysis, note the daily dose it used, and set it against the label. L-carnitine: PhenQ provides 300 mg/day against the 1,000–3,000 mg the meta-analyses used. Chromium: 40 mcg/day against 200–1,000+ mcg studied. Caffeine: 150 mg/day — inside the studied range. Three ingredients, three different verdicts, one method.
Do the caffeine arithmetic
If the label contains stimulants, add them to your day: coffee, tea, energy drinks, pre-workout — then compare the total against the ~400 mg/day general ceiling for healthy adults. PhenQ contributes 150 mg/day, which is why the brand advises nothing caffeinated after 3 pm.
A 30-second label triage
When you're holding a bottle in a store and want a fast read.
- Serving size and servings per containerConvert every figure to “per day” before judging anything.
- Count the blend linesOne or more proprietary blends? The deep check is impossible — treat claims accordingly.
- Find the stimulantsCaffeine anhydrous, yerba mate, guarana, bitter orange: add them up against your day.
- Google one dose, not allPick the headline ingredient, find its key study, compare doses. Under-dosed headlines are the category’s most common pattern.
- Check the audit lineGMP-certified, third-party tested, or nothing? “Made in a GMP facility” is a floor, not a distinction — but no audit line at all tells you more.
Label-reading questions
What is the first thing to check on a supplement label?
The serving size and the number of servings per container. Every other number on the label is per serving, and a “per serving” that means two capsules quietly halves each figure if you read it as per-capsule. PhenQ’s label lists per-capsule amounts with a two-capsule daily dose — so every figure doubles.
Why are proprietary blends a problem?
A proprietary blend lists ingredients in order but only the blend’s total weight — so you can know that a formula contains an ingredient without ever knowing whether the dose reaches the range its studies used. Fully disclosed labels like PhenQ’s (all 13 ingredients with exact amounts) let you run dose-vs-study checks; blends are designed to prevent exactly that.
What does %DV tell me on a supplement label?
Daily Value percentages are set for nutrition, not weight loss. On PhenQ’s label, iodine at 150 mcg is 100% DV and copper at 2 mg is 111% DV — meaning the supplement covers normal nutritional needs for those micronutrients. That is useful context, but it says nothing about whether a dose matches the amounts used in weight-loss trials.
See the method applied, dose by dose
All 13 PhenQ ingredients, each checked against the studies its claims come from.
Read the ingredient review