Writing in this punishing summer heat, I am driven to once again ponder that anecdote about the little boy who asked his grandmother: “Why do you drink hot coffee on a hot day?” There seems to be twin question: “Why eat hot soup on a hot summer day?” If we were in South Asia where the often hot spicy food can reputedly refresh a person on a sweltering day, the question acquires an even more mind-boggling dimension.
Along with the myths and personal preferences on hot and alcoholic drinks during the summer, there is also that question about what meals are best suited for summer. Light as in salads? Cold like gazpacho and cold coconut soup? Why? Does the brain send signals that only certain types of food can satisfy a person on hot days? To extend the question even farther, is eating a satisfying activity at all when it is so darn hot?
There is an interesting study about heat, taste and appetite. It was published as a book in 1993 entitled Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations. Quite dated but still interesting.
From Chapter 10, Effects of Heat on Appetite:
Common knowledge suggests that people eat less when it is hot, and that they eat ”lighter” and “cooler” foods. (This impression is reinforced by a casual survey of newspaper and magazine suggestions for summer meal planning.) As with most impressions derived from common knowledge, systematic evidence is needed to support these assertions. What does the scientific literature have to say about the effects of heat on food intake and food selection?
The subsequent discussion goes on to show that our perception of how heat affects appetite might be subjective if not misleading.
…one may ask whether appetite differs in summer and winter. Even within the seasons, of course, there may be considerable variability in temperature; does appetite suffer during a summer heat wave as compared to normal summer weather? Even more acute variations in temperature are available for examination, owing to the prevalence of air-conditioning. If, during a summer heat wave, one eats in an air-conditioned dining room, is appetite controlled by the outdoor or indoor temperature?…
…how hot one feels is not simply a matter of the environment; one’s own activity may generate heat, so that being active may be functionally equivalent to raising the environmental temperature. Indeed, eating itself has thermogenic effects, so that not only does heat affect appetite, but appetite may affect heat.
The meaning of appetite should also be clarified… Appetite refers to the subjective desire to eat, whereas hunger usually refers to a more objective deprivation state. These terms are not unrelated, but it is preferable to think of hunger as a true need that often produces a felt desire (appetite). Distinguishing between hunger and appetite becomes useful when considering the possibility that one may desire to eat something even in the absence of a need for it…
Very interesting. Next time I ponder about why drink hot coffee on a summer day, I’ll think of the answer after relating the question to all of the quotes above.