There's no one right answer as to what you should be eating. Most of these principles people are talking about which include categorical exclusions of things (ie don't eat bread) tend to be techniques that people use to prevent themselves from overeating/under eating/whatever the case may be. For example, if you were eating a diet which contained NO processed carbs at all, and all carbs came from fruit or vegetables, it would be insanely hard to get fat on such a diet for various reasons.
On the other hand, you could design a diet which was let's say 40% carb, 40% protein, 20% fat, in which all of the carbs came from wheat bread and milk (to pick on two things people above are disapproving of). If you followed this diet, ate the right macros, timed your nutrients appropriately, and ate at a ~500 calorie deficit, you'd cut fat. If you did the same and ate at a 500 calorie surplus, and assuming you were working out appropriately, you'd gain muscle. By contrast, you could design a diet which produces the same results and which had you eating only 30 carbs per day, none from bread and none from milk.
There's no one size fits all. Things that are bad for you to do on one type of diet are not bad on another type. If you're on a low carb diet then you can't be eating much, if any, bread. If you aren't on a low carb diet then you can. Some diet types work better for some people. Some people hemorrhage muscle on a low carb diet, some people don't. Some people function well on an intermittent fasting regime and some don't. You need to choose one type of diet at a time and try it out, and see how it works for you. Definitely don't try to throw together a bunch of random principles from different diets and try them all at once. That approach definitely won't work.
Like these guys have said, you need to do research.