The Nutri-Score is a packaging label first adopted by France, and recommended by other EU countries and the WHO.
The idea is that you can compare to packaged foods (for example, boxes of cereal) and get a rough sense of which ones are less unhealthy.
Where does the formula come from?
The 2022 Nutri-Score algorithm.
Who made this?
I'm a programmer named Allen Pike. It's open source, so you can contribute or file an issue.
Why do some foods get a good number but still a C grade?
The 2022 algorithm prevents manufacturers from stuffing sugary or calorie-dense foods with protein in order to get an "A" grade. Over a certain density threshold – which almost all snack bars exceed – the letter grade ignores protein content.
IMO this penalty should be more gradual – there are two SimplyProtein bars that get an A and a C just because one barely meets the threshold and the other doesn't. An opportunity for a future algorithm improvement.
Why does it say it's just for snacks?
There are variants on the Nutri-Score algorithm for beverages and other food types, so I started with snacks. If there's interest I could expand this.