Placing blanket terms on whether certain foods are good or bad is a very dangerous game. When the dosage and the context of the food within ones diet is far more important. An example would be a glass of red wine has numerous health benefits yet an over consuming would have a large number of negative effects.
Also claiming that only non-processed foods are good and processed foods are bad is more complicated than you would think. Whey protein is processed yet has numerous benefits (derived from milk).
Fat gain is due to an over consumption of calories, typical quote on quote bad foods tend to have more calories per gram and are often easier to consume in greater amounts (often leading to a caloric surplus & therefore weight gain).
Quote on quote healthy foods tend to be less calorically dense, therefore harder to over consume which will (if there is a caloric deficit, lead to weight loss) however you can still get fat eating healthy food if you are in a caloric surplus.
Energy balance by the end of the day is still king when goals are body composition related.
An exception to foods being good or bad is hydrogenated fat (should be avoided as much as possible).
You may here terms like “sugar is toxic or bad” This is ridiculous. This is dose dependent. a number of fruits contain fructose (fruit sugar) you may here a number of “experts” telling you to avoid fruit because of this. Again this statement is ridiculous because of the huge number of benefits to eating fruit. Sugar is an example which should be moderated but not eliminated.
To conclude: stating foods as good or bad is a dangerous game when the dose and context are not considered.
Eliminating certain foods unless there is an intolerance issue is again unnecessary. Realise by eliminating certain foods you may miss out on numerous benefits from the foods you have eliminated.