With large swaths of the country sizzling due to oppressive heat, many Americans are feeling parched. But just how much water will keep them properly hydrated and healthy?
It depends, said Laura Acosta, a registered dietitian nutritionist and instructional associate professor with the University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS) food science and human nutrition department.
Recommended daily water intake varies by age, sex, activity level and body size, she said. General public health guidelines recommend about 11 cups per day for women and about 15 cups per day for men. A more customized estimate based on body size can be reached by dividing one’s body weight in pounds by 15. Children, who become dehydrated more easily than adults, need more water per pound. A 10-pound child, for example, needs between 2 cups and 3 cups of fluids a day, and a 90-pound child needs between 8 cups and 9 cups.
Although these guidelines exceed the well-known, “eight-cups-a-day” maxim, Acosta said it’s important to remember they include water consumed through both drinking and eating. Many fruits and vegetables, including oranges, watermelon, cucumbers, lettuce and tomatoes, naturally contain significant amounts of water. Broths and soups – particularly clear ones – are also water-rich foods.
“So, you’re not necessarily chugging 11 to 15 cups of water a day,” she said.
Hydrating through beverages doesn’t have to be boring, either. While drinks containing caffeine, alcohol and added sugar can have dehydrating effects and should generally be avoided, sparkling water is just as hydrating as still water. Infusing water with fruit and herbs or using sugar-free flavoring drops can also make it more appealing.
Acosta suggests increasing motivation by using a bottle labeled with time markers that indicate consumption goals. Setting reminders or associating daily activities with drinking can also be helpful.
“Consider something you do on a regular basis, like brushing your teeth or eating a meal. Perhaps that’s the time to take a sip,” she said.
She cautions, however, that water is not always the most effective hydration choice.
Someone engaged in vigorous activity loses electrolytes — essential minerals like sodium and potassium — through sweating, and water alone cannot restore them, Acosta said. Instead, grab a sports drink or combine water with a salty snack, like pretzels or nuts.
“You don’t necessarily need a commercial sports beverage,” she said. “While these can be helpful for athletes needing just the right balance of water, electrolytes and carbohydrates to fuel performance, most people can rehydrate quite effectively with just water and a salty snack if they’ve lost some water from sweating.”
One of the simplest methods to gauge whether any hydration-boosting technique is working is tied to the bathroom.
An adequately hydrated person will feel the urge to urinate every three to four hours, and their urine should be a light-yellow color, Acosta said.
“And be sure to pay attention to how thirsty you are,” she said. “If you start to feel thirsty, there’s a good chance you’re already somewhat dehydrated.”