Hydration and Temperature: Are the Rumors True?
Hydration is extremely important. As we move into the summer months with warmer weather, our body will be craving water to replenish itself. Our body is made up of over 50% water and as you age that percentage can get less and less. All that water has a long list of duties! It does things from “insulating your organs and lubricating your joints to forming the very building blocks of cells. And of course, the water that escapes you in sweat and urine helps to cool you off and rid your body of waste” (Hamer, 2019). People consume water in different ways. I know some who say warm water is their preferred way to hydrate, where others prefer ice cold water especially on hot days. There are some old wives tales that say cold water assists in weight loss because the body has to work hard to warm the water up, so everyone should drink cold water. Other rumors say that hot water assists the body’s absorption abilities, so for efficient hydration one should drink only hot water. Is there really a difference? Is there any truth to these rumors?
A study by the University of Connecticut (UCONN) examined beverage temperature’s influence on hydration. The rationale behind this study was based on exercise performance benefits and preference: “Maintaining an appropriate level of hydration is optimal for maximizing exercise performance. Further, maintaining an appropriate level of hydration during exercise in the heat will not only assist in maximizing exercise performance, but will also increase the body’s ability to dissipate heat and enhance cardiovascular function” (Adams, 2013). Many of the major takeaways from their study involved individual palatability. Palatability is the pleasure reward provided by foods or fluids that are agreeable to the "palate", which often varies relative to the homeostatic satisfaction of nutritional, water, or energy needs (Friedman, 1976). Their first finding was that beverage temperature showed an increase in palatability and fluid ingestion. Their lit-review found a “50% increase in consumption when colder beverages were used during exercise and resulted in a smaller change in body mass (a hydration state equaling ~1.3% body mass loss) than warmer fluids” (Adams, 2013). Why is this? Well, when exercising the body is trying to reduce the core temperature. It usually does this via sweating; however, cooling via water consumption is not a bad idea as well. The study mentioned that “it is theorized that ingestion of cold fluid or an ice slurry mixture acts as a heat-sink which yields a larger heat-storing capacity in the body and has the potential to reduce core temperature during exercise. It has also been postulated that with ingestion of cool fluid, sensory systems in the body are activated and in turn affect central drive thus improving performance, especially in the heat” (Adams, 2013).
I bet now you're wondering, what if you’re not exercising? Is there any benefit on the resting body from drinking cold vs. warm water? Many of the rumors I mentioned above are in fact based in holistic medical practices like Ayurveda and Chinese medicine. The idea that different water temperatures influence weight comes from the way these traditional medicines think about digestion. It is understood that “cold water actually slows down the entire digestive system by constricting blood flow to the stomach and intestines and slowing enzyme secretion, which in turns causes lymphatic stagnation and a slower metabolism” and hydration where “room temperature and warm water…have the opposite effect, helping increase circulation to your digestive system and stimulating your ‘agni’, or digestive fire” assisting in hydration mechanisms (Bunch, 2021). The reason why these facts are not widely known is because there are some contradictory sources, one of which come from Columbia University’s Ask Alice. The source states information similar to the UCONN study, mentioning how colder water assists in body cooling and “people generally enjoy drinking cold beverages more than warm ones, so studies indicate that they’ll likely drink more water, known as drinking ad libitum (or drinking for pleasure), if they have a cold supply” (Ask Alice). It also states that “people who work, are physically active, or live in hot areas may want to consider drinking cold water because colder fluids leave the stomach more quickly than warmer ones, which allows for faster rehydration” (Ask Alice).
Overall, the most important factor is preference. Whatever makes you motivated to drink more water should be the temperature of water you drink. The more palatability and preference you have to drink your preferred temperature water, the more quantity you will drink and hydrated you will be!
References:
Bunch, Erin. “Plant-Based Skin-Care Ingredients This Derm Swears By | Well+Good.” Well+Good, https://www.facebook.com/iamwellandgood, 14 May 2021, https://www.wellandgood.com/plant-based-skin-care-sky-organics/.
Friedman MI, Stricker EM. The physiological psychology of hunger: a physiological perspective. Psychol Rev. 1976 Nov;83(6):409-31. PMID: 1005583.
Hamer, Ashley. “How Much of Your Body Is Water? That All Depends | Latest Science News and Articles | Discovery.” Discovery, Discovery, 1 Aug. 2019, https://www.discovery.com/science/How-Much-of-Your-Body-Is-Water.
Is Drinking Cold Water Harmful? | Go Ask Alice! https://goaskalice.columbia.edu/answered-questions/drinking-cold-water-harmful. Accessed 23 May 2021.
M. Adams, William. “The Beverage Temperature and Influence on Hydration .” Korey Stringer Institute - University of Connecticut, June 2013.
