How Much Weight Can You Lose by Drinking 8 Cups of Water a Day?

Although it's calorie-free and we already have a great deal of it in our systems, water may have the power to act as a phenomenal weight-loss aid. You've heard the adage that drinking 8 cups a day promotes better health, but it can also help you lose weight, especially if you knock back a couple of glasses right before meals.

A thin woman is drinking bottled water. (Image: Brand X Pictures/Stockbyte/Getty Images)

Benefits

According to MayoClinic.com, drinking 8 cups or more of water per day provides benefits that go beyond weight loss. It prevents dehydration, flushes toxins out of your organs, keeps your tissues moist and healthy, and delivers nutrients to the cells that need them most.

Expert Insight

In 2010 research from Virginia Tech nutrition professor Brenda Davy, subjects who drank two glasses of water before eating each major meal lost nearly 30 percent more weight than participants who did not drink the water and followed the same low-calorie diet. On average, the water drinkers ate 75 to 90 fewer calories at each meal and lost close to 16 lbs. over the 12-week study period.

How It Works

Davy isn't positive about why drinking water before meals and throughout the day can help you lose weight, but she has a few theories. One is that water acts as a natural appetite suppressant. It fills your stomach to some degree, curbing overall hunger and leading to a lower net calorie consumption. Another theory is that water fills you up in the same way that other drinks do, such as soda or juice, but it helps contribute to weight loss because it's free of calories. CNN Health physician nutrition specialist Dr. Melina Jampolis also suggests that drinking more water can help you slim down because it can be hard for the body to differentiate between hunger and thirst, and having water may satisfy cravings that initially seemed to indicate hunger.

Weight Loss

There's no way to tell how much weight you can lose by drinking 8 cups of water per day, because the amount depends on how many calories you eat as well as how much physical activity you do. As the National Institutes of Health points out, the only proven way to lose weight is to burn more calories than you consume. Although drinking 64 oz. of water daily may help you lower your total calorie consumption, it's not a guaranteed method. However, if you do end up reducing calories because of drinking more water, you are likely to post results similar to those in Davy's study, which indicate that you may lose just over 1 lb. per week.