How can I get my 4 year old brother to eat?

He only wants to eat chicken nuggets, hot dogs, and any other junk food laying around the house. I want to break that habit of his, he needs to learn to eat other things, too. I babysit him everyday, and my parents are real light on him. They give him whatever he wants, so I'm trying to be the parent while they're gone. I offer him rice, or eggs, or cereal, but no, he always wants hot dogs. What should I do? I tell him if he eats whatever I give him, I'll give him a hot dog or whatever he wants and he doesn't accept the offer.