it woudl depend on his height......i'm like that too and i'm 19 sometimes i get in these moods when i'm never satisfied and i can just eat pounds upon pounds of food. i wouldn't worry about it....if you start getting overweight (look up a BMI calculator and it will tell you you're ideal weight for your age range/height) then you might wanna slow down but until that point, do what your body tells you, it's usually right