Staying hydrated takes more than water

As the temperature heats up and we’re spending more time outside, it gets much easier to become dehydrated. The body is constantly losing water through the skin, from breathing, and, of course, urine.

As the temperature increases, sweat glands release more water onto the skin so water can evaporate and cool the body. Those refreshing trade winds speed up evaporation and mask the amount of fluid lost because you don’t even notice you are sweating — a process called insensible perspiration.

The proper amount of water in the body is essential for the most basic body functions.

Thousands of chemical reactions require water for everything from digestion to muscle contraction. Consequently, dehydration can cause a variety of health problems including headaches, constipation, fatigue, sore muscles and joints, dry skin, heart palpitations, loss of appetite, difficulty thinking clearly or concentrating, increased the risk of kidney stones and abdominal pain due to inflammation.

QUESTION: How do you know if you are adequately hydrated?

ANSWER: There is no standard blood test for dehydration. Generally, thirst is considered a reliable indicator of underhydration. However, for some people, especially older individuals, thirst may not be triggered until severe dehydration sets in.

In general, urine should be a light yellow color. Deep-colored urine can be an indication of inadequate hydration. One note of caution is that high intake of vitamin B2 (riboflavin) from a fortified food or dietary supplement makes the urine bright yellow. This has led some athletes to consume excess water, which also impaired performance and caused health problems.

The amount of water needed is dependent on things like body size, activity level, calorie needs, pregnancy, breastfeeding status, and of course, the climate. A general guide by the Institute of Medicine is to consume from a variety of beverages and foods about 2.7 liters (91 ounces) of water for females and 3.7 liters (125 ounces) for males.

Q: What helps the body hold on to water?

A: Water consumed without adequate protein, sodium and potassium is more quickly filtered into urine.

Consequently, salty snacks (in moderation) can slow urine loss. Also, sipping water slows down its absorption rate and likely slows urine production.

Alcohol and caffeine can increase the rate of urine loss. On hot days, consider lighter alcoholic beverages and consume water or other nonalcoholic beverages between each alcoholic drink.

Don’t wait until you are thirsty to drink and always include a variety of beverages along with straight water. If you wakeup at night, have some water by your bed and have at least a few sips after a bathroom trip.

Q: What are other potential causes of dehydration?

A: Any activity that increases respiration and sweat speeds up water loss. This includes conditions like fever, diarrhea, and taking certain medications.

Alan Titchenal and Joannie Dobbs are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa.