Why do we human beings have cravings? And, usually, cravings for things that are not the greatest. I mean, when’s the last time you had a craving for some broccoli? But chocolate? For sure.
Some cravings are the result of particular deficiencies. For instance, some people have pica — a craving to eat dirt or other non-nutritive substances — and such people are usually lacking iron in their diet. This is probably one reason that pica is more common in pregnant women than in the same women before or after pregnancy or in men.
But there are more common cravings. Potato chips. Cake. Fried food. Why?
There are various theories. Certainly marketing plays a part in the craving for chips and such, but there is probably more to it than that. One theory is that during human evolution, there were frequent periods of famine and, during the good times, people had to eat what they could so they would have reserves to call on when the famine came: If you were skinny before the famine you were dead afterward.
It is also true that salt is a vital nutrient. If you don’t get enough salt, you will die relatively quickly; salt used to be so valuable that it is the basis of the word salary. In the modern developed world, salt is very cheap and getting too little is very rarely a problem — we get too much salt, not too little — but evolution has not had time to catch up to the modern world and still tells us “go get some of that good salt”.
There is an excellent cookbook: Salt, fat, acid, heat: Mastering the elements of good cooking (I reviewed it here: https://medium.com/@peterflom/a-review-of-two-excellent-cookbooks-c47fb82a851) in which the author, Samin Nosrat, makes the case that good food is always based on salt, fat and acid and usually on heat as well; the art is balancing these properly. Some of this is due to chemistry: Salt has properties that no other molecule has. But the reason these things make food taste good to us is that our taste buds evolved to make it so.
And cravings do get worse based on conditions. For instance, if you read old English cookbooks you will see recipes for things that don’t look appetizing at all. Suet pudding, for example, is a dessert based on beef or lamb fat. You’re probably thinking “ick”. But why was it in the cookbook? Well, like salt, fat is also needed. If you get no fat at all, you will die quickly. Like salt, though, this is rarely a problem in the developed world, but it was a problem in England for a long time, where meat was a luxury, oil was uncommon, and the meat that was available was often dried — which removes a lot of the fat. So, people developed a craving for suet pudding — they needed the fat.
The third item in Nosrat’s list, acid, doesn’t seem to have the same cravings attached to it. But acid is not a vital nutrient. You can go without it and live a normal lifespan. Acid does make food taste good though.
And heating makes food taste better and also makes more of the calories in the food available to us; when food was scarce and famine common, that was a very good thing.