Staying well hydrated has positive effects on virtually every system in your body. It keeps your heart pumping and your joints well lubricated, and regulates body temperature.
Drinking enough water can stave off problems like kidney stones and constipation. Adequate hydration may also improve cognition and your mood. But calculating the amount of water you need daily is more complicated than you might think. “The idea that everyone needs 8 cups of water a day is a helpful starting point, but hydration is not one-size-fits-all because everyone’s body, lifestyle, and health goals are different,” says Grace Derocha, RD, CDCES, a spokesperson for the Academy of Nutrition and Dietetics.
Here’s what to know about how various factors affect the amount of water you need.
How Much Water Should I Drink?
These are the general recommendations for adults:
- About 3.7 litres per day for men (about 16 cups)
- About 2.7 litres per day for women (about 11 cups)
These totals include water consumed in other beverages such as tea, coffee, sparkling water, kombucha and coconut water.
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:
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.
The intensity and duration of exercise affect how much you sweat and your subsequent fluid needs. The temperature also affects how much you sweat, as does your body weight and composition. Further, you don’t have to visibly sweat to become dehydrated, which can happen while swimming in a pool or lake, or skiing on a winter’s 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, thus need different amounts of fluid.
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 experience a reduced sense of thirst and may need to be more mindful about drinking regularly – even if they don’t feel thirsty.
Research has found that chronic dehydration is a common problem in adults.
“Dehydration can exacerbate or make other health conditions worse,” says Kalisha Bonds Johnson, PhD, RN, 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 also result in urinary tract infections, which can lead to delirium and exacerbate symptoms of dementia until corrected.”
Body Weight and Birth Sex
Hydration needs are influenced by the surface area of the body, metabolic rate, and body 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 people born female, those born male generally need more fluid to support their increased body mass, lower average body fat, and increased calorie burn each day. Men also 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 litres) per day total – with about 3 cups of that specifically to support milk production.
Diet Quality
The foods you eat affect your hydration and the amount of fluid you need to drink.
If you eat ample fruit and veges each day, you don’t need to drink as much water.
Some fruit and vegetables have higher water content than others. Watermelon and spinach, for example, are especially hydrating, as they are almost 100 percent water by weight. Soup is another fluid-rich food that can help you meet your target water intake.
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 make you dehydrated.
Don’t Flood Your System All at Once
Drinking water gradually throughout the day is important. However, drinking excessive amounts of water at once may increase the risk of an extremely rare condition called hyponatremia, or water intoxication, which occurs when the electrolytes in the body become depleted. This is more likely to affect endurance athletes or people with kidney disease.
“Sodium is essential for maintaining normal fluid balance, nerve function, and muscle activity,” says Derocha. “When there’s too much water and not enough sodium, water starts to move into cells, causing them to swell.”
Symptoms of hyponatremia may include nausea and vomiting, headache, confusion or disorientation, muscle cramps or weakness, fatigue, seizures, coma, or even death in severe cases.
Derocha says that in general, people should listen to their bodies to help guide how much water they need.
“Instead of rigid rules, I encourage people to listen to their body’s cues. Thirst, urine colour (aim for light yellow), energy levels, and even mood can all be helpful indicators of hydration status,” she says.
The Takeaway
Staying well hydrated is critical for keeping your body healthy and can also have positive effects on cognition and mood. While there are general guidelines for how much water people should drink, hydration needs can vary widely depending on your sex, weight, and fitness habits. Water intake can also be increased by eating foods with a high water content. Though it’s very rare, it is possible to consume too much water, which can be dangerous. In general, listen to your body when figuring out how much water to drink. Be aware of how your age or other conditions might affect your water intake needs.
SOURCE: Everyday Health
