There exists a broad variety of easy low fat recipes. Big advantage: Most of those low fat recipes are also easy to prepare.
This is how I prepare it - really simple:
Saute 1 onion (cut in small cubes) in a pan with 1 teaspoon olive oil. After 2 minutes add 3 - 4 tomatoes in cubes (fresh or from a tin) and some water. Add 1 low-sodium boillon cube and seasoning according your taste and let it simmer 5 - 10 minutes. At the end puree the Napoli sauce with a blender. Decorate with basil leaves.
Another not so clean option is to use a Napoli sauce package that you prepare with water. In Germany you get such packages from the brands Knorr or Maggi - both in excellent quality, without artificial ingredients.
By the way, this above presented lowfat dish you can order in every Italian restaurant. It is not only low fat, but usually inexpensive and it is quicker prepared than a pizza.
You prefer pizza? No problem, if you order a pizza bread instead with a mixed salad then you can also save a lot of fat calories!