How to Read a Nutrition Label in Thirty Seconds
A doctor explains the four numbers worth checking on any food label, why per-100g beats per-serving, and which front-of-pack claims mean nothing at all.
The short version
- Read the per-100 g column, not the per-serving column. Serving sizes are chosen by the manufacturer and are often smaller than anyone eats.
- Four numbers do most of the work: sugar, saturated fat, salt or sodium, and fiber.
- Front-of-pack claims such as low fat, natural, immunity or high protein are marketing; the back-of-pack table is the regulated part.
See a doctor promptly if
These are the signs that change this from something to read about into something to act on.
- Using labels to restrict intake to the point of skipping meals, or feeling unable to eat food without a label
- New need to check labels obsessively alongside rapid weight loss
Turn the packet over, find the per-100 g column, and look at four numbers: sugar, saturated fat, salt, and fiber. Everything on the front of the pack is advertising; the table on the back is the regulated part.
That is the entire skill. The rest is knowing what counts as high and what the tricks are.
Why per 100 g and not per serving#
Serving sizes are set by the manufacturer, and they are frequently smaller than any real person eats. A bottle of drink that contains "2.5 servings", a bag of crisps split into two, a cereal box using a 30 g portion when most people pour 60 g. The per-serving column is where the flattering numbers live.
Per 100 g is the only column that lets you compare two products honestly, because it is the same denominator every time. US labels lead with per-serving, so check the serving size and how many servings the pack contains before you read anything else.
The four numbers and what counts as high#
| Per 100 g | Low | High |
|---|---|---|
| Total sugars | 5 g or less | more than 22.5 g |
| Saturated fat | 1.5 g or less | more than 5 g |
| Salt | 0.3 g or less | more than 1.5 g |
| Fiber | . | 6 g or more is genuinely good |
These are the UK traffic-light thresholds, and they travel well as a rough screen anywhere. For drinks the sugar thresholds are lower, because people consume far more grams of liquid than of food in one go.
The ingredients list tells you more than you think#
Ingredients are listed by weight, heaviest first. If sugar, glucose syrup, invert syrup, honey, concentrated fruit juice or maltodextrin appear in the first three, the product is substantially a sugar product regardless of what the front says.
Watch for the same ingredient appearing under several names, which spreads it across the list and pushes each entry further down. This is legal and extremely common.
Claims that mean nothing useful#
"Natural", "wholesome", "farm fresh", "supports immunity", "boosts metabolism" and "artisan" are unregulated in most markets. "Low fat" is regulated but often means the fat was replaced with sugar or starch. "High protein" is regulated by threshold, yet a high-protein chocolate bar is still a chocolate bar.
"Fortified with vitamins" is worth noticing only if you actually need that vitamin. Adding vitamin C to a sugary drink does not change what the drink mainly is.
The one comparison worth making in a shop#
Pick up the two products you are choosing between and compare the same per-100 g line on both. That takes about ten seconds and is far more useful than trying to judge a single product against an ideal.
Salt is where this pays most. Two loaves of bread, two jars of sauce or two packets of noodles from the same shelf can differ threefold in salt, at identical price and near-identical taste.
Where this fits#
Label reading is a small, reliable skill that supports whatever eating pattern you are working with. It will not, by itself, change your weight. The fuller guide to weight, metabolism and why diets fail explains why the harder problem is appetite and adherence rather than information.
Common questions
How much sugar is too much on a label?
Should I look at salt or sodium?
Do calorie counts on labels have to be exact?
Sources
Still not sure what this means for you?
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