Dieters who drink more water have greater weight loss, according to a new review of several prior studies.
Researchers at the Berlin School of Public Health, Charité University Medical Center Berlin in Germany, led the new review of the water studies. Eleven studies fit their criteria. Three of them showed that increased water intake among dieters was tied to greater weight loss.
One study found that dieters who drank 16 ounces (500 ml) of water before each meal lost five more pounds over 12 weeks compared to dieters who followed the same low calorie plan but didn't consume water before meals. The water drinkers also ate 75 fewer calories at each meal. That may not sound like much, but a deficit of 225 calories a day adds up over time.
Yet another study found that women who increased their water consumption while they dieted lost more weight than those who kept it below one liter a day.
It's not clear how water might help people shed pounds. One possibility is that water could inhibit feelings of hunger which may help people reduce their food intake.
Another possibility is something called "water-induced thermogenesis." The idea is that drinking water itself increases energy expenditure of your body. It has an energy consuming effect, yet this is not well studied.
How much water? Current recommendations stipulate men should drink 3 litres (13 cups) of water each day and women need 2.2 litres (9 cups). Women who are pregnant need an additional 1 cup (250 ml) of water each day; breastfeeding moms require an extra 4 cups (1 litre).
Children, aged 1 to 3 years, need 1 litre (4 cups) daily and 4 to 8 years olds require 1.3 litres (5.5 cups). Teenagers need to drink more - about 1.8 litres (7 cups) for girls and 2.6 litres (10.5 cups) for boys.
Physical exercise and hot weather drive up the body's need for water so you need to drink even more.
It's not only plain water that hydrates you. Everything you drink - excluding alcoholic beverages - counts towards your daily water requirements. Once you factor in coffee or tea, milk on cereal, a breakfast smoothie and so on, you're probably doing better than you think. (Alcohol is a diuretic meaning it causes your body to lose water. Caffeine has a very mild diuretic effect, which diminishes with daily consumption.)
While studies suggest that drinking water before meals enhances weight loss, studies don't always show that people who drink more water are slimmer. However there are other benefits.
One study found that women who drink water, rather than sugary drinks, had a slightly lower chance of developing diabetes. And women who don't drink plenty of water have greater odds of getting kidney stones.
Source: The American Journal of Clinical Nutrition, online June 26, 2013.
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