A smaller final weight can make the same assumed nutrient total more concentrated per gram. That does not prove that cooking created calories. It means your portion calculation needs the final measured batch weight, with the model’s limitations stated.
Hold one assumption constant
Imagine a fictional batch with a calculated total of 1,200 calories. Before a water-only loss it weighs 1,000 g; afterward it weighs 800 g. Under the explicit assumption that the counted nutrients remain in the batch, density changes from 1.2 to 1.5 calories per gram.
A 200 g portion changes meaning
At 1,000 g yield, a 200 g portion is one-fifth of the batch and calculates to 240 calories. At 800 g yield, it is one-quarter and calculates to 300. The portion mass stayed the same, but its fraction of the batch changed.
Do not overextend the water-only model
Draining fat, discarding cooking liquid or leaving food on the pan may remove more than water. Ingredient totals then may not represent the retained cooked batch exactly. A yield measurement by itself cannot identify which nutrients were lost.
USDA’s food-description documentation and NIST’s measurement resources support using compatible food states and measured amounts. The original numbers here illustrate a fixed-total model; they are not cooking-loss data for a real recipe. State that assumption if you use the method, and avoid presenting the result as laboratory-verified nutrition.
Sources and example boundaries
- USDA: Foundation Foods documentation
Food descriptions, portions, missing nutrients and sample variation.
- NIST: Metric Kitchen
Using appropriate kitchen measurements.
All food figures and prices in the worked example are invented to explain the method. They are not restaurant nutrition, tested recipes, shopping prices or personal dietary advice. Use the current label for the product you actually have.