I never tried chocolate pizza, but I eat whatever I want. In contrast to the rest of the week where I avoid refined sugar and carbs. Having said that, I barely crave for sweets nowadays. There were other times. About 10 years ago I weighed 130 kilograms (287 pounds).
Normally I eat a homemade Pizza or burger, or a bunch of french fries, butter rice or noodle stew on cheat days. But often I skip the cheat day completely. I prefer a well-made salad with turkey meat strips or smoked/steamed fish over any mass-produced fast food. I also don't need candies when there's a fresh fruit salad on my plate. I rarely eat pork or beef. I love poultry and fish, although not necessarily tuna.
My nutrition is very similar to the Paleo diet, but I eat all fruits and vegetables. For example I also eat potatoes, but normally I don't fry them.
The most important thing you should change when you have nutrition-related health problems: Stop eating refined sugar and white flour products. But I don't need to tell you this because cats don't eat such stuff.