First, Vitakraft pellets are terrible. Pellets should be just plain hay, no nuts, seeds or colored bits included.
Second, how do you know he's eating too much? What exactly is his diet like? How much hay? How many pellets? How many veggies?
Pigs should NEVER be without hay. It's the most important thing in their diets.
Adult pigs should be limited to 1/8 cup of pellets per day.
And pigs should have a varied veggie diet that should definitely include red or green leaf lettuce and bell peppers, as well as other veggies.