Drinking More Cold Water Burns a Few More Calories

You May Burn a Few More Calories, But You Can Drink Too Much

Woman drinking water from water bottle
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Does drinking more water really help dieting? A small study says drinking more cold water may help you burn a few more calories each day. How many? You burn about 50 calories per quart (or liter) of cold water, or about 25 calories per typical water bottle full of cold water. The effect mostly comes from the body needing to heat up the water in your digestive tract. It's a small effect, about the equivalent of five plain M&M candies.

How much water you should drink each day regardless of dieting is a common question. Apart from the water you get in food, medical references say women should drink about nine cups of beverages each day (73 ounces) and men should drink 12.5 cups (100 ounces) of beverages. With exercise, you should replenish the water you lose through sweat. See how much water to drink for walking and exercise.

Why Should You Drink More Water When Dieting?

Many diet plans advise you to more drink water when you want to lose weight. Drinking more water doesn't simply "flush fat" as is sometimes claimed, but there are reasons to do so.

  • Drinking a big glass of water whenever you feel hungry and before a meal or snack fills the stomach briefly and makes you feel fuller and perhaps stop eating sooner.
  • Breaking down body fat and muscle during weight loss produces wastes that must be eliminated through the kidneys. Drinking enough water is important to keep the kidneys functioning to remove these wastes.

    Drinking Cold Water Briefly Increases Metabolism

    Drinking 500 mL of water (a half-liter or about a pint) increased the study participants' metabolism briefly, for about a half hour. In that time they burned an extra 25 calories. That's about a quarter of a piece of sliced bread, or five M&Ms. The researchers theorized that most of the effect comes from warming the water in the stomach. In the male participants the calories came mostly from stored fat, in the women it came from stored carbohydrates. The paper was published in the Journal of Clinical Endocrinology and Metabolism, December, 2003. It was conducted by researchers in Berlin. This is one more reason why drinking cold water is a good idea when exercising.

    Should You Drink Eight Glasses of Water a Day?

    The study provides some support for the general recommendation to drink eight glasses of water a day while dieting. For most people that would add a liter or two (a couple of sports bottles full) to their regular water intake. The extra calorie burn would be about 100 calories a day if drinking 2 liters (2 quarts or 4 water bottles full) more than usual.

    Dangers of Drinking Too Much Water

    Don't start drinking an extra gallon of water a day.

    That can kill you, especially if you are fasting or eating very little. Water taken in must be in balance with body salt - electrolytes. The body needs to maintain salt balance or risk hyponatremia with heart attack and even death.

    Drinking too much water dilutes the salt in your blood and tissues and can kill you. Healthy athletes have died from drinking too much plain water and not replacing salt. Dieters should not plunge into drinking gallons of water a day in hopes of burning a few more calories. Drink an extra few glasses, yes. But a gallon is too much.

    Drinking and Walking

    Exercise such as walking causes your heart rate and breathing rate to rise and you lose body water through increased respiration and sweat.

    Walkers should drink a large glass of water an hour before walking, then drink about a cup of water every mile. When you finish walking, drink a glass of water. Guidelines for the marathon and half-marathon now say to "drink when thirsty" rather than pushing water, in order to prevent hyponatremia - drinking too much with replacing electrolytes. See how much water to take along or have access to on your walk.

    Sources:

    Michael Boschmann, Jochen Steiniger, Uta Hille, Jens Tank, Frauke Adams, Arya M. Sharma, Susanne Klaus, Friedrich C. Luft and Jens Jordan. "Water-Induced Thermogenesis" Journal of Endocrinology and Metabolism. December 2003, 88 (12): 6015.

    National Academies of Sciences, Engineering and Medicine, Health and Medicine Division. "Dietary Reference Intakes Tables and Application." http://www.nationalacademies.org/hmd/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx.

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