You can use two forms. Either "Mięso to jedzenie" or "Mięso jest jedzeniem". When you use "to" you don't have to change ending of "jedzenie" ;)
If you have an "X is Y" sentence and both X and Y are noun phrases - yes, the constructions are interchangeable. With "to", Y stays in Nominative, with "jest" (and its forms), Y changes to Instrumental.
If Y was an adjective, the only option is "jest", but Y stays in Nominative.
For (a lot) more info, you can read here: https://www.duolingo.com/comment/16373167
Damn articles. I would have everything without an error since I started the course, if it wasn't for them.
Sorry, what's the exact question? There are two options here: "Mięso to jedzenie" (Nominative) or "Mięso jest jedzeniem" (Instrumental).
But is meat really a food? Meat is found within our bodies and should not be consumed by humans and therefore it is debatable whether or not meat is a food. Any thoughts? Any myśli regarding this?