I started a new diet. Why am I always hungry now?

I used to eat really unhealthy foods. Lots of fast foods snacks candy junk food with no discretion. Im 24 and I weigh 155lbs. I started eating only healthy foods, mostly proteins. Eggs, LOTS of fruits, and whole grain breads if any. No saturated fats, refined sugars, and much less sodium. But no matter how much I eat I never feel full and I feel like I eat more because I'm always hungry. Is there some medical explanation for this?