A person who eats a mixed diet of plants and meats is a omnivore.
Vegetarian or a Vegan
Cannibalism.
Gannet
A vegetarian.
A person that eats all the time is called greedy. If you know a person that eats all the time, it's likely they will get fat. If they don't get fat and they eat all the time, then that is just the way they were born. edit- greed is where you want and keep everything for yourself where as if you eat a lot you would be called a glutton
What is eaten is food.
That's a carnivore.
A slimming diet
A person who eats only one type of food is called a monophagist.
Any person or creature that eats both meat and vegetables is considered an omnivore. A person who only eats meat is called a carnivore and a person who eats only eats vegetables is called a herbivore.
I would say food chain.