Our physical body needs food and water in order to survive, and in the absence of these things, starvation, followed soon by death will be the end result. In general, most people have a pretty good idea, that their automobiles will only run on the appropriate fuel for that car, which is why, you don't see people filling up their gas tanks with water, or other stupid stuff, which will ruin their car; as well as in general, people understand that proper care and maintenance are fundamental keys for sustaining not only life in general, but material things that we utilize each and every day. This then leads to the question; if we are intelligent enough to recognize that things of some worth to us have specific requirements to maintain them in good condition, than we probably too want to treat our body as if it really matters vitally to us by making good decisions.
For instance, most people understand that excessive smoking and excessive drinking, will take their toll on our bodies to which we will suffer from cancer, or cirrhosis of the liver, or other associated physical ills, not to mention that it will likely impair our judgments and damage family relations. So too does excessive caloric intake which will over a period of time, increase our body fat, our girth, and our weight, to such an extent that the extra weight that we carry upon our physiques will take a toll on our bodies to the point that we may be prone to suffer from diabetes, high blood pressure, and heart disease, as well as often having lower self esteem.
The thing is that the foods that we consume each and every day most definitely have an outcome on not only our physical health, but our mental well being, psychological feelings, and overall demeanor. This means, that all things being equal, we should want to consume the foods that are more beneficial for us, and to try to stay away from the foods that are detrimental to us, as quite obviously, not all foods are the same in substance or effect for our physical body. The finding and the knowing of which foods that are more desirable to partake of, isn't necessarily very easy, as we are inundated everyday with all sorts of commercials, ads, and propaganda, that appeal to the emotional parts of our being, to which beneath the surface, the product may or may not be profitable for us.
Additionally, news reports, media, books, and friends, provide us with all sorts of contradictory information, that even if we are quite diligent about eating the "right" foods that the definition of "right" appears to be in flex all of the time. If we think that we can short circuit this process by simply only eating foods that taste good to us, we often will find that people will gravitate, most unfortunately to things that are sweet as opposed to neutral or bitter tasting foods, and sweet foods, in particular processed sweet foods, because of their sugar content have been shown to be almost conclusively not good for our bodies.
The thing is our body is our own, and ultimately it's up to us to make good food choices, and to then implement those choices into our diet. After all, food is fuel, and we should want to run our body on the fuel that is most beneficial for us or clearly understand the tradeoffs if we don’t.