Match nutrition to the edible food described by its source. Bones, peel, shells and discarded trimmings can be part of the purchased weight without being part of the portion you eat.
USDA’s Food Buying Guide distinguishes food as purchased from edible portions. Its institutional purchasing examples are useful for understanding the distinction; they are not individual diet prescriptions.
A hypothetical trimming example
You buy 1,000 g of a food for $8. After removing inedible material, you have 700 g of edible food. This is an invented yield, not a typical value for a particular food.
| Quantity | Calculation | Result |
|---|---|---|
| Edible yield | 700 ÷ 1,000 | 70% |
| Cost per 100 g bought | $8 ÷ 1,000 × 100 | $0.80 |
| Cost per 100 g edible food | $8 ÷ 700 × 100 | About $1.14 |
| A 175 g edible portion | 175 ÷ 700 | One quarter of the edible batch |
These are two different cost questions. The checkout price stays $8; the amount available to eat changes the unit cost.
Use the nutrition entry that matches
If an entry describes boneless edible meat, use the edible meat weight rather than weighing the bone with it. If you weigh cooked food, select a matching cooked entry. Removing bones and cooking are separate changes; one percentage does not account for both.
For a packaged product whose label already describes its edible serving, use that serving basis. Do not reduce the label’s serving count a second time unless it actually includes the material you discard.
Yield does not tell you protein loss
A 70% edible yield does not establish that 70% of every nutrient remains. It only tells you the weight relationship in this example. You need a matching nutrition source for the edible portion before calculating its protein.
Compare protein cost when some food goes unused, or check raw and cooked weight bases before entering a recipe.
Sources and scope
These sources support the factual explanations above. Worked label examples are illustrative where stated. Restaurant comparisons use the listed U.S. portions; availability and local recipes may differ.