The instinct to reach for ice-cold water during a heatwave is not only ineffective but may actually impede the body’s ability to cool itself, according to a growing body of physiological research. Valery Litvinov, a senior researcher at Perm National Research Polytechnic University, told TASS that cold drinks activate thermoreceptors in the mouth and throat, which the brain interprets as a threat of overcooling. This triggers vasoconstriction in the skin, reducing heat dissipation and paradoxically raising the risk of overheating. Hot drinks, by contrast, stimulate sweating—the body’s most efficient natural cooling mechanism—making unsweetened tea or coffee a more effective choice in extreme temperatures.

Separately, digestive specialists have detailed how icy beverages affect the gastrointestinal tract. Silvia Gómez Senent, a neurogastroenterologist in Spain, described the “cold water paradox”: while water is essential for digestion, very cold water can cause local vasoconstriction in the stomach, temporarily slowing gastric emptying and leading to bloating, heaviness, or mild spasms in sensitive individuals. The effect is not dangerous for healthy people, she noted, but is more pronounced after large meals or during intense heat, when the body is already managing multiple stressors. Ice cream, with its combination of extreme cold, fat, and sugar, can compound the sensation of sluggishness.

Other common habits amplify post-meal discomfort. Argentine health advice, citing MedlinePlus, identifies eating too quickly and chewing insufficiently as the most frequent digestive error. Rapid consumption forces the stomach to work harder on poorly broken-down food, while swallowed air contributes to distension and gas. In Nigeria, where high-glycaemic staples such as pounded yam, white rice, and plantain dominate lunch plates, postprandial somnolence—the “food coma”—is widely reported. Surveys suggest over half of adults regularly experience it. The mechanism involves a sharp insulin-driven drop in blood glucose after a heavy, starchy meal, compounded by the diversion of blood flow to the gut. A short walk after eating, rather than lying down, significantly improves blood-sugar regulation and alertness.

Hydration choices further complicate the picture. Indonesian health warnings, drawn from clinical sources, caution that caffeine and alcohol act as diuretics, accelerating fluid loss precisely when the body needs to conserve it. Alcohol also impairs the hypothalamus’s ability to regulate temperature, increasing the risk of heat exhaustion. Viewed together, the findings from multiple regions converge on a counterintuitive heat strategy: favour warm or room-temperature drinks, eat slowly and in modest portions, and avoid diuretics. With red alerts still in effect across parts of southern Europe, the advice offers an evidence-based shift for millions seeking relief, and public health agencies are expected to incorporate the updated understanding into their heat-preparedness guidance.