I am often asked by friends, family and patients how much water they should be drinking. We’ve all heard how important it is to drink water. You may have heard you need eight glasses of water a day to be healthy, or that drinking more water can help you lose weight. And what about caffeine – does that count? Is water sufficient to replenish fluid losses during exercise? There’s a lot of information floating around regarding water and fluid intake. Today we’ll look at some of these questions and concerns.
Do I need to drink eight glasses of water a day?
Ask anyone how much water you should drink, and this is most likely the response you’ll get. However, there has never been a study or medical investigation to substantiate this claim. The Institute of Medicine, (they conduct scientific research and provide recommendations for health issues) has concluded from its studies that healthy individuals need only to respond to their thirst mechanism in order to meet hydration requirements. They estimate this to be about 91 ounces (more than 11 glasses) for women and 125 ounces (more than 15 glasses) daily for men.
I know what you’re thinking. That’s even MORE than 8 glasses a day! Don’t worry. This estimate includes ALL fluids, including those from non-water liquids (like coffee, juice or soda) as well as water content from food. A balanced diet of 2,500-3,000 calories provides about 34 ounces of water (more than four glasses) which counts towards your total. The bottom line is to drink if you’re thirsty and you’re probably fine.
Do caffeinated beverages count?
Caffeine is commonly thought have a diuretic effect, meaning it causes fluid loss through urination. There is often confusion as to whether caffeinated beverages are hydrating or dehydrating. What studies have shown is individuals who do not drink caffeine regularly can have a small diuretic effect from infrequent large amounts of caffeine. This would be someone who rarely drinks caffeine drinking four cups of coffee. People who regularly drink caffeine build a tolerance to this effect and even large amounts of caffeine do not have a significant diuretic effect. In fact, caffeine in modest serving sizes, such as that from one soda, coffee or tea beverage, have very little if any effect on hydration.
Does drinking water help me lose weight?
You may have been told when you feel hungry, drink a glass of water because you may instead just be thirsty. While this isn’t exactly true (thirst and hunger are regulated by different hormones), drinking water before eating can help you feel fuller, and subsequently you eat less. There has not been much research regarding water and weight loss, however a few studies have shown people who drink water before meals eat fewer calories. Substituting caloric beverages (sweet tea or soda) for water can also add up to additional pounds lost.
Should I drink water or Gatorade when I’m exercising?
For most light or moderate intensity exercises, water is all that’s needed. Hyponatremia, a potentially serious condition in which sodium concentration in body fluid is too low, can be caused by a combination of excessive sodium loss through sweating and replenishment with water, which contains no sodium. This condition is very rare during moderate exercise and is usually observed with endurance activities such as marathons and ultra-distance activities. If you plan on exercising in excess of two hours, an electrolyte beverage may be a good idea. But for most people engaging in light to moderate exercise, even cardio, water is perfectly fine.
Keep in mind you would need to walk or run about 1-1.5 miles to burn of the energy from a 20-ounce sports drink, so if weight loss is a goal then it’s best to stay away from the sports drinks.
Tips for increasing your water intake
Get an easily portable and reliable water bottle. This is my best advice for increasing fluid intake. You can avoid paying for bottled water and fill it throughout the day. Get one with a fun pattern or your favorite sports team. My favorite water bottle is the free one I received from The Women’s Hospital after delivering my child. It has a large straw so I always drink more when I use it. I often joke with my husband that if I lose this bottle I’ll have to have another baby so I can get a new one!
Add a dash of lemon juice or fresh berries to your water to give it a dash of flavor. In the spring and summer I add fresh mint from our back yard as well.
Check out your urine color. In most well hydrated individuals urine should be a light yellow or straw color. If it’s unusually dark, grab a glass of water. Drinking every time you go to the bathroom will ensure you’re replenishing what comes out.
Order water at restaurants. This saves you $2 and doesn’t alter your palate the way flavored drinks or beverages may, allowing you to better enjoy your food.
Start your day hydrated. Drink a full glass of water with your morning medications or right after you brush your teeth. Set the tone for your day by beginning it hydrated.
This article is meant to provide general health information about water and hydration. If you have a health condition requiring fluid control, talk to your health care provider.
Institute of Medicine report on dietary reference intake: water, potassium, sodium, chloride and sulfate
American College of Sports Medicine Roundtable on Hydration and Physical Activity: Consensus Statements. Douglas J Casa, PhD, ATC, FACSM, Priscilla M Clarkson, PhD, FACSM, and William O. Roberts, MD, FACSM
Maughan RJ, Griffin J. Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet. 2003 Dec;16(6):411-20
Muckelbauer R, Sarganas G, Fruneis A, Muller-Nordhorn J. Association between water consumption and body weight outcomes: a systematic review. Am J Clin Nutr. 2013; ajcn-055061