Why 7,700 Calories Per Kilogram Is Only Roughly True
A kilogram of fat is worth about 7,700 kcal. That is a fair figure for pure fat tissue, and only a rough one for real weight loss.
- The rule comes from Wishnofsky in 1958.
- Weight lost is never pure fat: some is lean tissue, and early changes are mostly water and glycogen.
- Hall's modelling showed the rule overpredicts loss over the long run.
- Estimates built on it need a window long enough for water shifts to average out.
Where the rule comes from
The rule that a kilogram of fat is worth about 7,700 calories, or 3,500 per pound, comes from Wishnofsky in 1958 and is the basis of nearly every weight loss projection ever made. It's a reasonable figure for pure fat tissue, and it's why Kriterion can work backwards from your weight trend to estimate what you're actually burning.
Why it is only roughly true
It's also an approximation with known limits. Weight lost is never purely fat: some is lean tissue, which carries far less energy per kilogram, and early changes are heavily water and glycogen rather than tissue at all. Hall's modelling work showed the rule systematically overpredicts loss over the long run for exactly these reasons.
What that means for estimates
This is why estimates built on it need a window long enough for water shifts to average out, and why the resulting number is bounded rather than trusted absolutely.
It is why Kriterion works your maintenance calories out from your own intake against your own weight trend, and then checks that arithmetic against what actually happened.
References
- Wishnofsky M. Caloric equivalents of gained or lost weight. The American Journal of Clinical Nutrition, 1958.
- Hall KD. What is the required energy deficit per unit weight loss? International Journal of Obesity, 2008.
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011.
- Thomas DM, Martin CK, Lettieri S, et al. Can a weight loss of one pound a week be achieved with a 3,500-kcal deficit? International Journal of Obesity, 2013.
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Kriterion is the app this reasoning is built into
It measures your maintenance calories from what you actually ate against what the scale actually did, tells you how firmly the number is pinned down, and checks its own past predictions against your results. Free logging, UK food data, and no ads.
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