Factors That Affect Fluid Needs
The general recommendations for water intake are a good starting point, but your individual needs can vary based on other factors, such as age and activity level. Here are some of the factors that influence how much water you need.
Activity Level
When you sweat during exercise or on a hot summer day, you need to replace the fluids you’ve lost by drinking more water.
Exercise intensity and duration affect how much you sweat and your subsequent fluid needs. Temperature also affects how much you sweat, as does your body weight and composition. Keep in mind, you don’t have to visibly sweat to become dehydrated. This can happen while swimming in a pool or lake, or while skiing on a winter day.
Calculating exact hydration losses from physical activity is complicated because people sweat at different rates. People of the same gender and weight, and with similar diets, will sweat different amounts in the exact same conditions, and thus need different amounts of fluid.
One way to monitor your hydration level is by noting the color of your urine. Lighter urine is a sign of healthy hydration, while darker urine can indicate that you’re not getting enough water.
Age
Children and teens need proportionally more water than adults, relative to their body size, especially during growth spurts and active play, says Derocha.
Older adults may feel less thirsty and may need to be more mindful about drinking regularly. Research has found that chronic dehydration is a common problem in adults. In older adults, the chronic dehydration rate in the United States ranges from 17 to 28 percent.
“Dehydration can exacerbate or make other health conditions worse,” says Kalisha Bonds Johnson, PhD, an assistant professor at Emory University’s Nell Hodgson Woodruff School of Nursing in Atlanta. “Dehydration or inadequate hydration can lead to confusion, poor blood pressure regulation, and poor kidney health. The effects of dehydration on the kidneys can result in a urinary tract infection, which can lead to delirium and also exacerbate symptoms of dementia until corrected.”
Body Weight and Sex
Hydration needs are influenced by the body’s surface area, metabolic rate, and weight.
“Muscle tissue is about 75 percent water, while fat tissue is only about 10 percent water,” says Derocha. “As a result, as body weight increases, fluid needs increase.”
Compared with women, men generally need more fluid to support their larger body mass, lower average body fat, and increased calorie burn each day. Men typically sweat more than women.
Pregnancy and Nursing
Pregnant women require additional fluids to maintain amniotic fluid levels, increase blood volume, and keep the baby growing steadily.
If you’re nursing a growing baby, you need to drink more fluids so that your body can make enough milk.
Derocha says that a nursing mother typically needs about 16 cups (3.8 liters) per day total — with about 3 cups of that specifically to support milk production.
Diet Quality
If your fruit and vegetable intake is low on a given day, a few extra glasses of water will compensate. Drinking extra water when drinking alcohol is also a good idea, as alcohol is a diuretic and can dehydrate you.
Read the full article here

