A friend lost about 30 pounds by (she says) just drinking a lot of water. Can you really lose weight that way?
Not quite. You lose weight by consuming fewer calories than you expend. But several studies indicate that drinking water just might help people consume fewer calories and even possibly increase their energy expenditure, so it can be an important tool in weight control.
One study, published in the November 2008 issue of the journal Obesity, indicated that drinking water was linked with greater weight loss, regardless of other factors. The study examined data from 173 overweight women ages 25 to 50 who participated in a Stanford dietary study. Researchers looked at their diet, physical activity, body weight, and other factors when the study began and at 2, 6, and 12 months. At each point, they asked participants to report their intake of drinking water; diet (0 calorie) beverages; fruit juice, milk or unsweetened beverages; and other beverages; as well as their food intake and physical activity. The women who drank more than 1 liter of water a day lost nearly 5 more pounds over 12 months, regardless of other factors including diet or physical activity. Interestingly, consumption of other calorie-free beverages didn't offer a similar benefit.
Another study, published in the December 2005 issue of the journal Obesity Research, examined data from 4,755 people who took part in the National Health and Nutrition Examination Survey from 1999 to 2001. Researchers found that people who reported drinking water (average of 1.5 liters, or nearly 6.5 cups, a day) consumed 194 fewer calories per day compared with those who reported not drinking water. People who drank water also tended to follow a generally more healthy eating pattern, consuming more fruits, vegetables, and low- and medium-fat dairy products.
Still, questions remain on how water consumption might affect calorie intake. For example, a study in the January 2007 issue of Obesity found that non-obese older adults (ages 60 to 80) tended to eat fewer calories at a meal if they drank 1.5-2 cups of water a half-hour beforehand; however, younger adults (ages 21 through 35) didn't experience the same effect. And, weight-loss researchers at Penn State University have not found a link between water consumption and weight loss, although they have found that foods with a high water content, such as soup, fruits and vegetables, help people feel fuller on fewer calories.
Although rare, it is possible to drink too much water, so don't go overboard. But the old standard of eight cups of water a day won't hurt, and you might be surprised at the results around your waistline.
Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1044, or firstname.lastname@example.org.
Editor: This column was reviewed by Julie Shertzer, registered dietitian and program specialist for Ohio State University Extension in the Department of Human Nutrition, in the College of Education and Human Ecology.