They way I trained my iguana to eat food like alfalfa is not to give in... They can go a long time without food, so all you have to do is give it what you want it to eat. Eventually, it will eat the food it supposed to eat. If he doesn't eat in the beginning don't worry, let him starve. when he is hungry enough he will eat it. Don't let it train you to feed only what it likes. Just make sure he is well hydrated.