eating behavior?

my 4 months old kitten eats good one day and the next day he doesn't have the same appettite, he acts normal otherwise, is this normal?

I dont know about normal but my 15 month old eats 1.5 cups one day and then 2 the next and one the next... Is the kitten eating aobut the same or widely varying amout

he's always been a finicky eater and doesn't eat the amount recommended, he goes to the bathroom everyday so i know he's eating what he needs, but yesterday it's was first time i saw him eat a lot most of the day and even ate the boiled chicken before bedtime so now i'm just a little confuse, maybe he's still full from yesterday feeding?