I am on a diet, but I get ravenously hungry.?

So today I ate, 3 times. I eat a sandwich for breakfast lunch and dinner. It consists of around 300 calories per sandwich. And I snack on a peanut butter granola bar (for the protein) I eat the sandwiches for the carbs and protein. They are on whole wheat, with a very light amount of mayo and some cheese and lettuce. Now I also exercise quite intensely for about 30-50 minutes with a 10 minute cool down walk. Why do I get so ******* hungry, by the end of the night I want to eat my whole pantry. I feel like an animal...