Think hours, not kilometers. On rides of under 1.5 hours, just water is fine. 2-3 hours, you'll need some carbs, probably throughout the ride. Over 3 hours, some protein is recommended. Doesn't take much, maybe 15% of calories. After the ride is the time to get some more protein and carbs down. Maybe 25g protein, 50g carbs after a 3 or so hour ride. Then a regular meal fairly soon.
Gym rats are frequently very into protein. Cycling isn't the same. You actually want to lose or maintain weight, certainly not gain it.