The 1 change I recommend, if I would only be allowed to make 1 recommendation, would be to eat only real, whole, unprocessed, fresh foods.
If you do that – whether you’re Vegan, Paleo, Gluten-free, Mediterranean, or even traditional American (modified to be unprocessed) – you’ll be a whole lot better off.
By definition you will have to eat more fruits & vegetables, and cook, or buy food from places that cook with good ingredients.
That’s it. It’s simple, if I can only say one 🙂