The 80:20 rule...
Let's start off by saying I think that this is the most sustainable way to structure your nutrition. This is an amazing rule that has worked for all of my clients because thats what I personally follow. So, for those of you who do not know, the 80:20 rule means 80% of your foods being nutritious, whole food sources while the other 20% being "treats". As always, calories are going to be what determines whether or not you lose weight, but having 20% of your calories coming from "feel good foods", makes the diet turn into a lifestyle.
Now, this isn't me telling you eat a bunch of fruit, and then follow it with some ice cream at night. You still have to eat Whole Foods containing all the vitamins, minerals, fiber, and all that other goodness needed for optimal health. Not to mention still getting in your protein.
Don't forget, as I always preach, you're main job is to get enough protein, that is the most important thing, especially if you're goal is fat loss. Then structure your calories to where you can still eat 20% treat foods and stay in a caloric deficit. It's really as simple as that. So don't let anyone (including yourself) tell you that you can't have a "treat" food every now and then!