Practical Guides
Nutrition label traps: serving sizes explained
The numbers on a label are accurate. What they're attached to is where the room for interpretation lives.
Trap 1: the serving is not the package
A bottle of soda or a bag of chips frequently contains two or three servings. All the figures on the panel — calories, sugar, sodium — describe one of them. Nothing is false, but reading the panel without checking "servings per container" understates what you actually consumed by a factor of two or three.
Trap 2: rounding to zero
Labelling rules allow amounts below a threshold to be declared as zero. A product with a small amount of trans fat per serving can legally be listed as "0g trans fat" — and if the serving is small enough, several servings still add up. Checking the ingredients list for "partially hydrogenated oil" is more reliable than trusting the zero.[1]
Trap 3: per 100g vs per serving
Comparing two products is only meaningful on the same basis. Per-100g figures are the fair comparison between brands; per-serving figures tell you what you'll actually eat. Manufacturers may choose flattering serving sizes, so use per-100g to compare and per-serving to plan.
Fast label check
Servings per container → calories per serving → protein → added sugar → ingredients list. The ingredients list is ordered by weight, so if sugar (under any of its many names) appears in the first three, the product is largely sugar regardless of front-of-pack claims. See how to read a nutrition label.
Frequently asked questions
Why do labels show more than one serving?
Serving sizes are standardized reference amounts, not a recommendation of how much to eat. A package often contains two or three servings, so the panel figures must be multiplied by servings per container to describe the whole package.
Can a product labelled 0g trans fat contain trans fat?
Yes. Labelling rules permit amounts below a threshold to be rounded to zero per serving. Checking the ingredients list for partially hydrogenated oil is a more reliable indicator than the declared figure.
Should I compare foods per serving or per 100g?
Use per-100g figures to compare brands fairly, since serving sizes differ between products, and per-serving figures to plan what you will actually eat.
Keep reading: How to read a nutrition label · Added vs. natural sugar · Trans fat explained