Many eat for taste, which is fine up to a point. The main foods are fresh fruits and vegetables, whole grains, whole cereals, fermented foods such as kimchi and sauerkraut and kefir. On a long and strenuous tour on a loaded bicycle you need healthful nutrition. Do your gut microbiome a favor and nourish it. Some foods strengthen it. Others slowly deplete it and cause health problems.
Some of the stuff some cyclists display as food is scary. Long distance hikers eat stuff that is cringe worthy, lots of highly refined carbohydrates, non-food junk that can be chewed and ingested with a sugar rush and cheap synthetic vitamins and minerals. It is made to cause addiction to oral gratification. It will slowly wreck your digestive system.
I watched a group of young women on you tube. They cycled across the US on the transamerica route. Time and time again they got stuck in dinky little towns with a small store. The garbage they had to use for energy was terrible, but their choices were limited to what was available. One or more of them commented on not feeling quite right after a while. I did not have to wonder why--ice cream, cheetos, potato chips, candy bars and other slop. I watched another cyclist who went to convenience stores in small towns. The edibles she got were what I would try to avoid eating in any way I could. When you are young and at your peak, your gut biome may withstand the onslaught of processed junk foods for a time, but as sure as the sun rises in the east, they will inflict a deleterious injury to your health over the long run.
If you will be a long distance between towns that actually sell food, be sure to carry with you something nourishing you can eat until you get to the next store that sells real nourishing food. If you carry just enough good food to get to the next town, and then you are limited to unhealthful ingestion, you will see what I mean. Medical journals say 80% of colon cancer can be prevented by diet and exercise. Why get all that exercise and negate it with adulterated foods? Heart disease, cancer, hypertension, high blood pressure, gout, diabetes and a list of other diseases are caused by poor diet and lack of exercise, confirmed by medical science. Some town up ahead has a store according to a map, but does it tell you what you will have to put in your body if you rely on that store for nutrition? Always carry enough real food to get you to the next real-food store.