Cooking spray is nearly pure fat, and the label on the can says zero calories and zero grams of fat. Nobody is lying. The serving size is about a quarter of a gram — a spray lasting about a quarter of a second — and US rounding rules let anything under 5 calories per serving print as zero, with fat under half a gram rounding to zero too. The numbers are legally accurate and practically meaningless.
That is the core thing to understand about the Nutrition Facts panel: it is a regulatory document, not a summary. Every figure is true for exactly one serving, and the serving is chosen by the manufacturer within FDA-defined ranges that only loosely track how people eat. The 2016 label redesign fixed the worst offenses — calories got bigger, an added sugars line appeared, and serving sizes moved toward reality, so a soda's serving became the full 12-ounce can rather than 8 ounces of it. But the panel still rewards reading in the right order.
Auditors do not read documents in the order they were laid out. They find the base unit, convert everything to a common denominator, then look for what was rounded away. The same method works on food, and it takes about thirty seconds per label.
Step one: serving size and servings per container
The serving size is the denominator for every other number on the panel, so it comes first. Ask two questions: how many grams is one serving, and how many servings are in the package? A "150-calorie" bag of chips listing 2.5 servings per container is a 375-calorie bag. Packages holding roughly two to three servings — small enough to plausibly be finished in one sitting — must now carry dual-column labels, per serving and per package, but plenty of packages sit just outside that rule, and the multiplication is left to you.
Then compare the stated serving to what you would actually eat. Cereal servings hover around 30 to 40 grams; weigh what lands in your bowl once and it will likely be closer to double that. Nothing on the label is wrong. It is answering a question nobody asked.
Step two: convert to per 100 grams
This is the auditor's core move, and it is one multiplication: divide any number by the serving weight in grams, then multiply by 100. European labels print a per-100g column by law, which is part of why serving-size games are largely an American art form. Per-100g numbers make any two products directly comparable and make the serving size irrelevant. Illustrative numbers from typical products:
| Label says | Serving size | Per 100 g | What the audit shows |
|---|---|---|---|
| Potato chips: 160 calories, 170 mg sodium | 28 g (about 15 chips) | 571 calories, 607 mg sodium | Among the most energy-dense items in the store |
| Canned soup: 890 mg sodium | 245 g (1 cup) | 363 mg sodium | Moderate density — but the can holds two servings |
| Deli turkey: 450 mg sodium | 56 g (2 oz) | 804 mg sodium | Saltier per gram than the chips |
| Breakfast cereal: 12 g sugar | 40 g | 30 g sugar | Nearly a third sugar by weight |
The deli turkey is the instructive row: gram for gram, it is saltier than the potato chips. Per-serving framing hides that completely, because the turkey's serving is heavier and mostly water.
Step three: triage with %DV
Percent Daily Value answers "how much of a full day's worth is in one serving," benchmarked to a 2,000-calorie diet. The FDA's rule of thumb is worth memorizing: 5 percent DV or less of a nutrient is low; 20 percent DV or more is high. That single heuristic sorts most packages in seconds — 45 percent DV of sodium in one frozen entrée is a finding; 3 percent is a pass.
The anchors behind the percentages: 2,300 mg of sodium, 50 g of added sugars, 20 g of saturated fat, 28 g of fiber. And remember that %DV inherits the serving-size problem — it is a per-serving figure — so use it for fast triage, and use per-100g for honest comparisons between products.
The added sugars line
Until the redesign rolled out, total sugars was one undifferentiated number: the lactose in plain yogurt and the syrup in flavored yogurt counted identically. The added sugars line separates them, and it changes verdicts. Plain yogurt showing 5 g total sugars and 0 g added is a different food from a fruit-on-the-bottom cup showing 15 g total and 10 g added, even though "sugars" once made them look like neighbors. Sugar arriving inside a whole-food matrix behaves differently from sugar poured in at the factory — a distinction covered in depth in added vs. natural sugar.
Cross-check the line against the ingredient list. Added sugar travels under many names — cane sugar, corn syrup, agave, honey, fruit juice concentrate, maltodextrin — and when several appear in one product, each can sit lower in the by-weight ordering than a single combined "sugar" entry would.
Sodium: audit everything that isn't sweet
Sodium is where per-100g thinking pays off most, because the salty-tasting foods are not the saltiest foods. Bread, deli meat, cheese, canned soup, and sauces deliver more of a typical American day's sodium than chips do. The Daily Value is 2,300 mg, and a single restaurant-style bowl of soup can clear a third of it. If you ever work from a European label that lists "salt" instead, sodium is 40 percent of salt by weight — multiply salt grams by 400 to get sodium in milligrams. Our sodium guide covers where it hides and what to do about it.
What the label rounds away
Rounding rules are the quietest trick on the panel. Trans fat below 0.5 g per serving prints as 0 g, so a food can declare "0 g trans fat" while containing partially hydrogenated oil — visible only in the ingredient list. The FDA revoked that oil's generally-recognized-as-safe status in 2015, so it is now rare, but old formulations linger. A subtler case: mono- and diglycerides are classified as emulsifiers rather than fats, so any trans fat they contain is exempt from the trans fat line entirely.
The ingredient list is the antidote, and it has its own audit logic: ingredients are ordered by weight, so the first three tell you what the food mostly is, and the last few tell you what was sprinkled in for shelf life and color. A fuller tour of what to look for there is in ingredient red flags.
How Nutrication uses this
Nutrication's grade is built to resist serving-size framing, because the core scoring runs on per-100g data. The Nutri-Score component of the grade — worth up to 30 of its points — counts penalty points against per-100g thresholds: for foods, sugar penalties begin above 4.5 g per 100 g and top out at 45 g (drinks are held to much stricter sugar thresholds); sodium penalties begin above 90 mg per 100 g and top out at 900 mg. A label can shrink its serving, but it cannot shrink its density. When a label lists salt instead of sodium, the engine converts at 400 mg of sodium per gram of salt — the same arithmetic as above.
The added-sugars distinction is built in, too. If a food is whole or minimally processed and its ingredient list contains none of roughly two dozen added-sugar markers — cane sugar, corn syrup, agave, fruit juice concentrate, and the rest — its naturally occurring sugar takes zero sugar penalty, and the breakdown displays it as "natural — not counted." Beverages get no such exemption: the first sugar threshold for drinks is zero, so any sugar at all in a drink costs points. Isolated added fibers like inulin and chicory root fiber earn only half the fiber credit, closing the mirror image of the added-sugar loophole.
Serving-size absurdities are handled directly. When a product doesn't state a serving weight, the glycemic-load measure falls back on category-typical servings — 40 g for breakfast cereal, 30 g for chips or crackers, a full 330 ml can for soda — because grading a soda on a 100 ml pour understated its glycemic load threefold. And when a label is missing saturated fat, sugars, and sodium entirely, the engine refuses to score that measure rather than treat blanks as zeros, which would produce a falsely favorable grade. The full six-framework system is laid out in how we grade.
What to actually do
- Read serving size and servings per container before anything else; multiply if you will finish the package.
- Divide any number by the serving grams and multiply by 100 to compare products on equal footing.
- Use the %DV shortcut: 5 percent or less is low, 20 percent or more is high.
- Judge sweetness by the added sugars line, not total sugars.
- Scan the first three ingredients and the last three — they tell different stories.
- Or scan the barcode and let the per-100g audit run for you.