An, R. The Official Journal of the British Dietetic Association, published online Feb. 22, 2016.;News release, University of Illinois at Urbana-Champaign.;CDC: "Finding a Balance."
If you’re already well hydrated and getting plenty of water, getting more water into your diet probably won’t make a lot of difference. But if you’re going through your days a little -- or a lot -- dehydrated, as many people are, getting enough water could help.
“In my experience, most people are not aware of how much they’re drinking and are not drinking enough -- many, as little as half of what they need,” says Amanda Carlson, RD, director of performance nutrition at Athletes’ Performance, which trains many world-class athletes.
How Water Boosts Metabolism
“Water’s involved in every type of cellular process in your body, and when you’re dehydrated, they all run less efficiently -- and that includes your metabolism. Think of it like your car: if you have enough oil and gas, it will run more efficiently. It’s the same with your body.”
“Your metabolism is basically a series of chemical reactions that take place in your body,” says Trent Nessler, PT, DPT, MPT, managing director of Baptist Sports Medicine in Nashville. “Staying hydrated keeps those chemical reactions moving smoothly.” Being even 1% dehydrated can cause a significant drop in metabolism.
Hungry or Thirsty? How Water Helps a Diet
It’s also very difficult for the body to tell the difference between hunger and thirst. So if you’re walking around feeling a gnawing sense of hunger, you might just be dehydrated. Try drinking a glass of water instead of grabbing a snack.
Research has also shown that drinking a glass of water right before a meal helps you to feel more full and eat less. “Many people do find that if they have water before a meal, it’s easier to eat more carefully,” says Renee Melton, MS, RD, LD, director of nutrition for Sensei, a developer of online and mobile weight loss and nutrition programs.
One study, for example, found that people who drank water before meals ate an average of 75 fewer calories at each meal. That doesn’t sound like a lot -- but multiply 75 calories by 365 days a year. Even if you only drink water before dinner every day, you’d consume 27,000 fewer calories over the course of the year. That’s almost an eight-pound weight loss.
The Digestive Health Benefits of Water
But getting enough water doesn’t just help you regulate how much you eat -- it helps you digest it properly, as well.
“Water allows your kidneys to function properly and filter everything they need to, and allows us to eliminate effectively and not be constipated,” Melton says. “People who don’t get enough fluids in their diet tend to be constipated.”
And that’s not all. The single biggest cause of painful kidney stones is chronic dehydration. When you don’t get enough water, calcium and other minerals build up in your urine and are harder for your body to filter out. They can form the crystals that make up kidney and urinary stones.
Doctors who specialize in pediatric kidney problems report seeing more kidney stones in children in recent years, and they believe it’s because of a combination of factors. Many kids aren’t drinking enough water. Also, many kids are overweight and eat a poor diet.
“I’ve been in this field for over 30 years, and I’d say that until about the last 10 to 15 years, you almost never saw stones in kids,” says Robert Weiss, MD, chief of pediatric nephrology at Maria Fareri Children’s Hospital of the Westchester Medical Center in New York. “Lately, the frequency is increasing dramatically.”
How Much Water Do You Need?
How can you know if you’re getting enough water to keep your metabolism cranking at peak efficiency and your digestive system functioning? The formula used to be “one size fits all” -- eight 8-ounce glasses of water a day. But that’s changed, experts say.
“It depends on your size and weight, and also on your activity level and where you live,” Nessler says. “In general, you should try to drink between half an ounce and an ounce of water for each pound you weigh, every day.” For example, if you weigh 150 pounds, that would be 75 to 150 ounces of water a day. If you’re living in a hot climate and exercising a lot, you’d be on the higher end of that range; if you’re in a cooler climate and mostly sedentary, you’d need less.
Another quick way to check: look in the bowl after you’ve gone to the bathroom. If your urine is clear or very light yellow and has little odor, you’re well hydrated. The darker and more aromatic your urine, the more dehydrated you are.
How can you build more water consumption into your day? Try these tips:
- Carry an insulated sports bottle with you and fill it up periodically.
- Keep a glass of water on your desk at work.
- Keep another glass next to your bed. Many of us wake up dehydrated first thing in the morning.
- Switch one glass of soda or cup of coffee for a glass of water.
- Drink small amounts of water throughout the day. Six glasses all at once isn’t good for you!