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How to Stay Hydrated in Hot Weather

Trust your sense of thirst to guide you in how much water you need to drink to stay hydrated in hot weather. Other liquids also count.

Hot weather means perspiration, because that is how the body cools itself. Evaporation of sweat from the skin results in heat loss-a good thing when the thermometer is over 90. But do you need advice on how to stay hydrated in hot weather? You just might, as there are a few myths that can be confusing.

Staying Hydrated in Hot Weather:

Q. My doctor told me to drink eight glasses of water each day now that the weather is hot. Is that really necessary?

I prefer coffee, tea or beer. Does that count?

A. All the fluid you drink counts, and so does the moisture in the food you eat. So if you have a bowl of soup or cereal, or enjoy a juicy fruit snack such as watermelon or a peach, all that liquid “counts” towards your hydration needs.

What Is Magical About Eight 8-Ounce Glasses?

There is a popular belief that drinking eight 8-ounce glasses of water daily is essential for good health, but that number is an estimate, not an amount that is set in stone. Your doctor is right that you probably need more water in hot weather to replace water lost in sweat. But precisely how much liquid you need to stay hydrated in hot weather probably depends on your size, activity level and how much you perspire.

There are certainly good reasons to focus more on water than on beer (which contains alcohol) or coffee and tea (which contain caffeine), though you don’t need to swear off any of them completely. People sometimes claim that the caffeine in coffee or tea causes more fluid loss than you gain by drinking them. That does not seem to be true.

So how much fluid should you be drinking? Your thirst is usually a good guide.

Athletes and Hyponatremia:

Athletes who exercise long and hard (marathon runners, for instance, or football players in practice at the end of the summer) often concentrate on getting enough water so they can stay hydrated in hot weather. That is crucial, of course. Dehydration is a real danger that can lead to cramps, heat exhaustion or even heatstroke or shock. Dry mouth, fatigue, thirst and decreased urine output could all be signals that the body is not getting enough liquid.

Drinking liquids when thirsty appears to be a sensible approach even for ultra-marathon competitors (International Journal of Sport Nutrition & Exercise Metabolism, online Apr. 20, 2016).

Drinking too much in an effort to prevent dehydration is also a danger because body sodium levels can drop too low. Here again, thirst is often the best guide, though for extreme athletes added electrolytes may be helpful. Deliberately increasing sodium intake doesn’t always protect ultra-marathon runners from hyponatremia or dehydration, however (Sports Medicine – Open, online Dec. 22, 2015).

Little Kids & Older Adults:

Thirst is not always as reliable in young children or in older people. Parents will need to pay attention to their children’s urine output and color. Dark urine usually indicates that it is concentrated and suggests that the person needs to be getting more liquid. That can also be used as a guide for older adults, who may need to pay more attention to fluid intake so they can stay hydrated in hot weather.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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