Ice cold juices and sodas, ice cream, halo-halo and maiz con hielo are popular all year round but most especially during the summer. Growing up, devouring them gave us the psychological effect that they actually cooled our body. Then, childhood fancies were replaced by education and we learned that sugar-laden sweets, even if ice cold, actually make our metabolism go faster and that results in increased body heat.
Ironic, isn’t it, how cold food can make us feel warmer. Just where did we ever get the (wrong) idea that ice cold drinks and ice cream cooled our body? And what if we drink sugarless cold drink like plain iced water — won’t that produced the desired cooling effect? Not necessarily, it seems.
Apparently, the wrong notion that cold food and drink do cool the body came from scientists who tested subjects who are fed with cold drinks or food and then inserting a rectal thermometer in them. The tip of the thermometer would find itself near the stomach where the still cold food or drink is and, ergo, the thermometer would register a reading lower than the normal body temperature. The wrong conclusion — cold food and drinks can really cool the body.
According to a new study, you have to sweat and the sweat must evaporate first to benefit from the cooling effect of anything you eat or drink. Sweating is releasing excess body heat. If that tall glass of iced tea or soda doesn’t make you sweat (and it most likely won’t), then, there is no cooling effect.
Unlike previous studies, Dr. Jay didn’t rely on just a rectal thermometer as a proxy for core temperature. Instead, he monitored metabolic rate and deployed eight thermometers on various parts of the body, plus a rectal thermometer and one inserted through the nose down the esophagus. Using an approach called “partitional calorimetry,” he was then able to obtain a much more accurate estimate of the total amount of heat entering and leaving the body.
The difference is subtle but crucial, because if you drink a big glass of ice water, you’ll have cold liquid sitting in your stomach – right above where you’ve shoved your rectal thermometer. As a result, the thermometer may register a lower temperature even though the rest of your body hasn’t really been cooled.
Sure enough, unlike previous studies, the new study found that drinking hot water triggered a sweat response that more than compensated for the heat of the drink. Cold drinks produced the opposite response, with a reduction in sweat cancelling out the cooling power of the drink. [The Globe & Mail]
So, there. A cold drink might produce some beneficial psychological effect but, really, there’s nothing better than a bath to cool the body.