Short answer: calorie counting is systematically inaccurate, and the errors run in one direction. Food labels are legally allowed a margin of error, restaurant figures are frequently understated, app databases contain user-submitted entries with no verification, and people under-report intake by 20 to 30 percent in controlled studies. None of this makes tracking useless. It makes precision an illusion and consistency the actual skill.
Set a target, then adjust it from real results rather than trusting the arithmetic.
Where the errors come from
| Source | Typical error | Direction |
|---|---|---|
| Packaged food labels | Up to 20 percent permitted | Either, often understated |
| Restaurant menu figures | Frequently 20 percent or more | Understated |
| App database entries | Highly variable | Both, unverified |
| Eyeballed portions | 30-50 percent | Understated |
| Forgotten items | Oils, drinks, tastes while cooking | Understated |
| Self-report overall | 20-30 percent | Understated |
Notice that almost every error runs the same way. That is why someone eating 1,800 tracked calories can stall: the real figure is closer to 2,300.
The label tolerance nobody mentions
Nutrition labelling regulations in most jurisdictions permit a margin of error, commonly around 20 percent, between the stated and actual values. A 200 calorie bar can legally contain 240. Across a day of packaged foods that accumulates.
Restaurant figures are worse, because portion sizes vary between locations and staff, and published values are usually based on a standardised recipe rather than what lands on your plate.
What to do about it
- Weigh solids, do not eyeball them. This single change eliminates the largest error source. A food scale costs very little.
- Weigh oils and fats especially. A poured tablespoon of oil is commonly two, which is 120 unrecorded calories.
- Use verified database entries. Prefer entries matching the packaging or official sources over user-submitted ones with round numbers.
- Weigh raw where possible, since cooked weight varies with moisture loss.
- Track everything, including tastes while cooking, drinks and condiments.
- Treat the number as relative, not absolute. Its job is to be consistent so you can adjust from it.
Why tracking still works
This is the important part. If your tracking is consistently 15 percent understated, that is fine, because you are not trying to hit a true number. You are trying to establish a baseline and then move it.
Eat at your tracked figure for two to three weeks, watch the weekly average weight, and adjust by roughly 10 percent based on what happens. The tracked number becomes a reliable dial even if it is not an accurate measurement. Consistency in method is what makes it work.
When tracking is the wrong tool
For some people, detailed tracking increases preoccupation with food in an unhelpful way. Portion-based approaches, habit changes and food quality rules produce results for many people without a single number being recorded. If tracking makes your relationship with food worse, that is a good reason to use a different method.
FAQ
How accurate are calorie counting apps?
The maths is exact; the inputs are not. Database entries are often user-submitted and unverified, and portion estimation adds further error.
Are food labels accurate?
Within a legally permitted margin, commonly around 20 percent. Not a scandal, but worth knowing.
Why am I not losing weight at 1,500 calories?
Most commonly, actual intake is higher than tracked. Weighing everything for two weeks usually reveals the gap.
Should I weigh food raw or cooked?
Raw where practical, since cooking changes weight through moisture. Be consistent either way.
What about the calories my watch says I burned?
Less reliable than your food log, not more. Validation studies put the error on wearable activity calories between 19 and 100 percent, which is why fitness tracker calorie counts should never be eaten back.
Sources
- Lichtman SW et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine, 1992.
- Urban LE et al. Accuracy of stated energy contents of restaurant foods. JAMA, 2011.
- Jumpertz R et al. Food label accuracy of common snack foods. Obesity, 2013.
- US Food and Drug Administration. Nutrition labelling compliance and permitted variance. fda.gov
- Hall KD et al. Methodologic considerations for measuring energy intake. Obesity, 2019.
General information, not medical advice.
Convert raw and cooked weights properly and calculate recipe macros per serving.
GramGoal Team. We build nutrition calculators and price-check the supplement market monthly. General information, not medical advice. See our methodology and affiliate disclosure.