Can you actually trust calorie labels?
The number on the package feels like a fact. 230 kcal. Exact. It isn’t — and that’s worth knowing when you track calories.
Labels are allowed to be well off
In the US, the FDA allows the real calorie count to be up to 20% higher than the label, and the product is still compliant. A meal labelled “500 kcal” may actually contain 600. The EU has similar tolerances. Labels are a guide, not a measurement.
Why that is
Calorie figures usually don’t come from measuring that specific product, but from the Atwater system: averages of 4 kcal per gram of carbs and protein and 9 per gram of fat. They’re averages across many foods, not exact values for your portion.
On top of that, how much energy you actually get depends on how well you digest and absorb it, how it’s cooked, even your gut bacteria. Two people eating the same thing don’t extract the same calories.
Restaurants are worse
For restaurants and menus the gap is often bigger. Studies have found differences of 10 to 50% between stated and actual calories. Notably, the dishes listed as “light” were on average the furthest off — sometimes 150 to 200 kcal more than stated. Fixed recipes (fast food) were more accurate than hand-plated sit-down restaurants.
What it means for tracking
Not that tracking is pointless — that chasing precision is. A banana isn’t “exactly 105.3 calories”. An honest estimate with a margin tells you more than a fake-precise decimal.
That’s why noots uses estimates: it shows a rounded number with a tilde (~250), shows
its sources, and never pretends to know your meal to the calorie. A barcode gives the exact
label value (with the same caveat that the label itself has a margin).
The good news: for your goal, that margin barely matters. Estimate consistently and you’ll still see your trend clearly — and the trend is what counts, not today’s exact number.
Read more about how noots estimates on the accuracy page.