The method here is deliberately simple, because simple is what makes it useful at the grocery store. For each food, we take the grams of protein and divide by the grams of fat, using values per 100 grams of the edible, cooked or ready-to-eat food. Standardizing on 100 grams matters: it lets a delicate flake of sole and a dense scoop of cottage cheese sit on the same scale, regardless of how big a typical serving happens to be. All of the numbers trace back to the U.S. Department of Agriculture's FoodData Central, the country's reference database for nutrient values, reflecting standard entries as of June 2026.
A few quick benchmarks will help you place any food you come across. Above roughly 20 to 1, you're looking at near fat-free protein — the leanest of the lean. Between about 8 to 1 and 20 to 1 sits the broad "lean" middle, where most white fish, shellfish, and poultry breast live. From 3 to 1 up to 8 to 1 is the moderate zone, the territory of chicken thighs and leaner cheeses. And anything below about 3 to 1 is, by the numbers, a fat food that happens to carry some protein.
One honest caveat is worth keeping in mind as you scroll. At the very top of the list, the fat figures are so tiny that a difference of a few tenths of a gram swings the ratio dramatically — a food listed at 0.3 grams of fat versus 0.6 grams can double or halve its score. So treat the leaders less as a precise podium and more as a tightly bunched cluster of "essentially fat-free" proteins. The ordering at the top is approximate, and that's a feature of the math, not a flaw in the food.
Want to judge a food yourself, right in the aisle? Glance at the Nutrition Facts panel and divide the grams of protein by the grams of fat. Above 20 to 1 is exceptionally lean, anything from 3 to 1 up to 20 to 1 is solidly lean to moderate, and below 3 to 1 means you're mostly buying fat. It's a five-second check that cuts through a lot of "high-protein" marketing.