Dieters have long been searching for a magic bullet which will help them lose weight. They've tried everything from prescription drugs to tropical plant extracts. A recent study suggests that their answer may have been flowing out of their taps all along: plain, ordinary water.
Dieters who drank two eight-ounce glasses of water before meals lost 40% more weight than those who didn't drink water before their meals.
Folklore and everyday experience suggest that drinking water can help people lose weight. But there has been surprisingly little scientific evidence supporting this. Until now.
In a study headed by Brenda Davy, an assistant professor at Virginia Tech, dieters who drank two eight-ounce glasses of water before meals lost 40% more weight than those who didn't drink water before their meals.
Davy suggests that the reason water works is likely because it fills up the stomach without adding any calories. The fuller people feel, the less they eat.
Drinking water can also help people lose weight when water replaces calorie-rich beverages such as soda. A 12-ounce can of soda contains about 10 teaspoons of sugar and 150 or more calories. Water has zero calories. People who have been drinking a quart of soda a day will cut at least 400 calories a day from their diet when they switch to water.
The study included 45 adults, aged 55-75. Half of the subjects drank 16 ounces of water before meals, the other half did not. All subjects ate a low calorie diet during the 12-week course of the study.
At the study's end, the water drinkers had lost an average of 15.5 pounds, while the non-water drinkers averaged an 11-pound loss.
There is no universally-accepted figure for how much water people should drink daily. The Institute of Medicine, which advises the Federal Government on science, suggests that people let thirst be their guide. The IOM does give general recommendations for daily intake of fluid (all liquids, including water): about 9 cups a day for women (2.25 quarts) and 13 cups for men (3.25 quarts).
It is possible to drink too much water, which can lead to a serious condition known as water intoxication. But the condition is highly uncommon, especially when compared to the number of people who could use a little help in shedding a pound or two.
The study results were presented at the 240th National Meeting of the American Chemical Society. The meeting was held in Boston from August 22-August 26, 2010.
Brenda Davy has a PhD in nutrition and is an assistant professor in the department of Human Nutrition, Foods and Exercise at Virginia Tech.