Is it normal that i am starving all the time

I eat a lot even though I don't weigh a lot and never have. I also gain and lose weight rapidly. Like ill lose 5-20 pounds in a few days sometimes. Every now and then I get severely hungry but I not sure what I am supposed to eat.

The answer is usually

Pancakes or french toast with orange juice
meats
or fruit smoothies

If I don't eat one of these I can literally be starving to death in a house full of food. I not sure why.

This doesn't happen all the time but it happens every few months and it drives me insane. On top of that, I can out eat my dad who is bigger than me and I always been very skinny and short. I have before eaten what three people would eat in one sitting and my family always eats way less than me.