Can Water Help You Lose Weight?

It's hot. And maybe you're sitting there wondering exactly how much water you should drink every day to stay healthy. Unfortunately, the answer isn't clear—it's also not eight glasses a day, no matter how often you've been told that. So how much is it? We've done the research, and the answer is complicated. Basically, just keep drinking.

Coming up with a one-size-fits-all water recommendation is difficult because our need for water varies based on age, size, activity level, and even the temperature.

The problem is so complex that the recommendation of the National Academies' Health and Medicine Division is basically no recommendation at all; the experts there state that most healthy people will be able to absorb an adequate amount of water from the foods and beverages they consume.

Jodi Stookey, PhD, a nutrition epidemiologist and hydration researcher with the Children's Hospital Oakland Research institute, disagrees: "Basically nothing happens in the body without water. Every thought, movement, and feeling is the result of water moving from one place in the body to another. If affects how you think, feel, absorb, digest, and metabolize. It should be clear that if water is limited, the world of our body is not going to be optimal." Stookey points to recent research that indicates increasing water consumption can have significant health benefits—among them, weight loss.

Stookey conducted a study that found drinking at least four glasses of water a day increased weight loss. "We think water can actually help promote weight loss in many ways," she says. "By substituting water for sugary beverages or juice, you've removed calories and carbohydrates. Then, if you have enough water, you can start seeing more efficient insulin pathways and an acceleration of fat burning."

In the absence of certainty about how much water we should be drinking, Stookey recommends reaching for water rather than concentrated juices, sugar-sweetened beverages, or even diet drinks. As this season of summer excess winds down, keep the H2O flowing.