Fast food has more sugar than you realize - the soda and sweet tea, obviously, but I mean the burgers and tacos, too. It's shocking how much sugar and refined carbs are shoved everywhere. They also usually have a lot of PUFAs, which we've been told for decades are healthier than saturated fat even though as they have become prevalent heart disease has skyrocketed.
The secret is to not try to go too off the deep end for health and focus on sustainability. Unless you like salad, you're not going to stick to a salad diet. You're better off finding a few healthy, whole food that requires little adornment and just eat that. Like, eggs and fish for example (and by that I mean eggs and fish not some weird frankenfood eggproduct and fish tendies). Those are fairly healthy, nutritious, and tasty foods. Find something that you like, figure out what 2000 calories is, and make the same thing every day. Do that for 6 months. The more you can simplify the better. People fail at diets usually trying to make these complicated recipes approved by Atkins or Oprah or whatever else and they last a day or 2 before giving up. Consistency and simplicity will win the day.