The most healthy way to nourish your body is to give it food that is as close to its natural form as possible. This does not imply that you must eat anything raw that should be cooked but it does mean that you should try to minimise the amount of processing that happens to that food between the time that it is reaped or killed and when it enters your mouth.
Keep in mind that the manufacturers are in the business of feeding the masses for their own benefit, not yours. They exist primarily to make a profit. If there are ways for them to make that profit by using inferior produce or by using a cheaper alternative that will taste as good, they may well do so. Even when reading the list of ingredients and nutrition information you cannot be sure exactly what is in that can of soup or frozen meal because low levels of additives don't have to be reported. You can be sure of what is in your meal if you prepare it yourself.
The food manufacturers add all manner of additives to their products and not all of them are good for your health. Some are added to maximise taste, for example salt and sugar. Personally, I find most prepackaged American foods much too salty for my palate. I think that they have progressively added more salt to their recipes over the decades to keep ahead of the American palate becoming accustomed to it, so their product always seems flavourful to taste buds that have already been sensitised by too much salt. Read the information labels on your cans to see the high salt content of some of these products. Salt absorbs water from its surroundings, so too much salt makes your body hold excess water. It also increases bad cholesterol levels in your blood. Not good for your health.
Various manufacturers have heeded the call from health authorities to reduce salt content but some of them have replaced it with more sugar, to enhance the flavour. The are compensating for lost saltiness by increasing sweetness. That is also bad for your health, the extra sugar translates into more calories, which make more fat if you don't burn them off. Also, read in an earlier post Watch What You Mix what the effects are of combining excessive sugars with proteins in your meals.
Bread choice is somewhere that you can improve the amount of processing in what you eat. Many of the choices are little more than air and highly processed white flour. They are not even tasty or pleasant to eat and they are awful toasted. The packaging tells that it is enriched with various vitamins and minerals. Frankly, it has to be enriched because so much natural goodness has been removed in the processing that it has little nourishment left in it. This stuff also has preservatives to stop it from going stale. You can forget a few slices in a packet in the back of your bread bin and it will still be soft 2 weeks later. You will have better digestion if you choose wholewheat and multi-fibre breads ahead of white air bread. It is also more filling, so you will feel that you have eaten something more substantial.
Salads made from fresh ingredients are always nice in hot weather. They are filling, have lots of fibre and the colourful ingredients are full of antioxidants. The fibre will improve your digestion and the antioxidants will help to ward of cancer by getting rid of free radicals in your system. The same applies to lightly steamed vegetables.
Food cooked at home from fresh is far more healthy than buying prepared frozen dinners from the supermarket. Many chain restaurants are just as guilty of over-salting their food as the manufacturers of canned of frozen dinners. You can continue eating this way out of convenience but think about what it is doing to your health.