My older brother is 38.

Every Sunday, me and my close family gets together to eat dinner at my parents. 

For many years now, my brother always makes a MASSIVE plate of food. Much larger than anyone else’s plate. But he hardly ever touches it. He walks around, talks, his food goes cold, and he takes it home with him. I have no idea if he eats it all at home, or throws it out. 

I’ve tried googling this, but to no avail. 

BTW - He’s not overweight - he just has a middle-aged-guy gut. 

Could this be an eating disorder? 
Suggestions?

Thanks