'Processed' is only a small part of the issue. The addition of sugars and fats to food you wouldn't reasonably expect to have much of either pushes the calorie counts way up - both of those additives broadly have 6-700 calories per 100g. Lean chicken is a little over 100 calories for the same weight.
Those 'well known' tuna lunches seem like a healthy lunch but they're 300 odd calories and a careful read of the label will tell show about a third of the calories are sugars/fats. If I make my own using tinned mixed beans, tuna and whole-meal rice, with the same calorie count the portion is twice the physical size (at least). 500 calories of that mixture (and some soy sauce) is a pretty good (large) healthy lunch.
I
have to keep under 2000 calories to not put on weight and keep over 1500 to aovid starvation responses - I've experimented and adjusted - I count them - and keep myself to 1800 a day more or less - which is why I've lost 35 pounds in two years
and kept it off.
There is no 'diet' that works long term, there's only 'changing your eating pattern for life'. And it's not easy
Pasta has a reputation as 'healthy'. It's not, it's a refined carbohydrate. It's no more a health food than white bread. Replace it with vegetables and you'll be far better off.
Slice, season well, fry in olive oil until both sides are dark brown.