You should drink at least 8 glasses of water per day.
There's no evidence to back that up. The Institute of Medicine recommends that men get about 125 ounces of water daily and that women get 91 ounces, but that includes water from all foods and beverages. Most people get enough hydration unless they're exposed to heat stress or they're very active for a long time.
About how much water comes from food?
The average person gets about 20% of their water for the day from food. An apple is 65% water. Bananas are 70% water. Broccoli is about 90% water.
Even foods that you might not think of as moist -- a slice of white bread (40% water), ground beef (53%), American cheese (28%) -- help.
While exercising, most people should break for water every 20 minutes.
On average, you should take a rehydration break at least every 20 minutes. Most people would stay adequately hydrated by drinking about 7 to 10 ounces of fluid every 10 to 20 minutes during exercise. But your exact need depends on things like how hard you're working, whether you are indoors or outdoors, and your age, gender, and weight.
It's also helpful to drink two cups of fluids (about 17 to 20 ounces) about two to three hours before a workout.
Which drink is the most dehydrating?
Alcoholic beverages have the most dehydrating effect. Coffee and other caffeinated drinks do make you urinate more, but overall, they're hydrating because of their water content. Juices, sodas, and other sweet drinks also are hydrating. Water is usually a better choice for hydration because it doesn't have extra calories.
How much water does the average adult lose every day naturally?
You lose about 10 or more cups of water every day just living: breathing, sweating, urinating, etc. Eating and drinking usually make up for it.
You may be dehydrated if your urine looks like apple juice.
An easy way to monitor your hydration level is to check the color of your urine. The darker your urine, the less hydrated you are. Drink enough fluids to keep your urine a lighter color. If your urine is clear or pale, chances are you are well hydrated.
Other practical ways to monitor your hydration status include keeping an eye on your body weight (you lose weight as you lose water) and perspiration (the more you perspire, the more water you're losing).
Drinking water can help you lose weight.
Drinking water could help with weight loss. Studies show that by drinking water, people tended to eat and drink fewer calories, probably because the water filled them up. As a result, they lost weight.
Both studies were short-term, however, and it's unknown if the results would have held up over a longer time.
You should avoid drinks and snacks with sodium when you're trying to rehydrate.
Sodium is something your body needs when you're trying to rehydrate, either during or after exercise. That's why sports drinks are often rich in sodium -- one of the "electrolytes" your body loses during exercise. Drinks and snacks with sodium also can trigger thirst and help you retain fluids. But too much salt can raise your blood pressure and worsen heart conditions in some people.
Is it possible to drink too much water?
It is possible to drink too much water. Healthy kidneys in an adult can process anywhere from 20 to 1,000 milliliters of fluid per hour. It's not easy to overload them, but it can happen. Getting too much water, especially in a short time, is dangerous. Symptoms of too much water include weight gain, bloating, nausea, and vomiting. Sudden cases of water intoxication can cause low blood sodium, which can result in headaches, confusion, seizures, and coma.
Images provided by:
American Academy of Family Physicians: "Hydration: Why It’s So Important."
American College of Sports Medicine: "Exercise and Fluid Replacement."
American Council on Fitness: "Fit Facts, Healthy Hydration."
The Academy of Nutrition and Dietetics: "Hydrate Right," "How Much Water Do I Need Each Day?" "Is Getting Enough Water a Concern in the Winter?"
American Medical Society for Sports Medicine: "Heat Illness."
American Society of Clinical Oncology: "The Importance of Hydration."
CDC: "Water: Meeting Your Daily Fluid Needs."
Clemson University Cooperative Extension: "Fluid Needs."
Harvard Medical School: "The Hazards of Too Much Water."
Institute of Medicine: "Dietary Reference Intakes : Electrolytes and Water," "Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate."
International Food Information Council Foundation: "Hydration: Does it Always Have to be Water?"
National Athletic Trainers' Association: "Inter-Association Task Force on Exertional Heat Illnesses Consensus Statement."
The Nemours Foundation: "Dehydration."
Practical Gastroenterology: "Water Intoxication: Considerations for Patients, Athletes and Physicians."
U.S. Department of Agriculture: "Nutritive Value of Foods," "Nutrition and Your Health: Dietary Guidelines for Americans."
U.S. Public Health Service Commissioned Corps: "Exercising in Hot Weather."
Dennis, E. Obesity , February 2010.
Stookey, J. Obesity , November 2008.
Vreeman, R. British Medical Journal , Dec. 22, 2007.
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