Skip to main content
ASK AN EXPERT
Got a question about a health story in the news or a health topic? Here's your chance to get an answer. Send us your questions about general health topics, diet and fitness and mental health. If your question is chosen, it could be featured on CNN.com's health page with an answer from one of our health experts, or by a participant in the CNNhealth community.




* CNN encourages you to contribute a question. By submitting a question, you agree to the following terms found below.
You may not post any unlawful, threatening, libelous, defamatory, obscene, pornographic or other material that would violate the law. By submitting your question, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your questions(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statment.
Thank you for your question!

It will be reviewed and considered for posting on CNNHealth.com. Questions and comments are moderated by CNN and will not appear until after they have been reviewed and approved. Unfortunately, because of the voume of questions we receive, not all can be posted.

Submit another question or Go back to CNNHealth.com

Read answers from our experts: Living Well | Diet & Fitness | Mental Health | Conditions

Expert Q&A

Can drinking lots of water help you lose weight?

Asked by Tony, Shelton, Connecticut

Open quote
Close quote

Is it true if you drink lots of water, it will help you to lose weight? Is it bad for your body if you consume too much of it?

Expert Bio Picture

Diet and Fitness Expert Dr. Melina Jampolis Physician Nutrition Specialist

Expert answer

Hi, Tony. Research does suggest that drinking plenty of water may help you lose weight. An abstract by Dr. Brenda Davy, associate professor of human nutrition, foods and exercise at Virginia Tech, presented at last year's obesity conference in Phoenix, Arizona, showed that people who drank two glasses of water 20 to 30 minutes before every meal lost weight more quickly initially and lost significantly more weight than those who didn't.

In another study by Davy and her group, published last year in the Journal of the American Dietetic Association, she found that people who drank water before meals ate an average of 75 fewer calories at that meal. This may not seem like much, but if you ate 75 fewer calories at lunch and dinner for the next year, you could lose about 14½ pounds! In addition, being even 1 percent dehydrated can cause a significant drop in metabolism, which can also interfere with weight loss.

Finally, it is very difficult for the body to differentiate hunger from thirst. If you don't drink enough water throughout the day, you may mistake thirst for hunger and eat more than you really need, which can also impair weight loss. So staying well hydrated is important, particularly if you are trying to lose weight. And don't forget to eat lots of water-based foods like soups, vegetables and low-fat dairy, which are equally important for weight loss, as they lower the calorie density of meals. That can help you reduce calories without reducing portions.

To answer the second part of your question, yes, drinking massive amounts of water (gallons and gallons) can cause a dangerous condition known as hyponatremia (low sodium levels in the blood), which can cause confusion, irritability and seizures and may even lead to a coma.

This condition is very rare in healthy people but can sometimes be seen in the elderly or in endurance athletes who sweat significantly and drink water only to replace lost fluids. Most people should be far more concerned with not drinking enough water versus drinking too much.

More Q&A

  • CNN's Medical UnitCNN's medical unit brings you the best experts available to answer your questions about current events and health issues that matter most to you.
Will jogging hurt an obese person's joints?asked by: Asked by John Simmet; St. Paul, Minnesota
Is creatine a safe supplement?asked by: Asked by Ralph; New York
What foods cause flatulence?asked by: Asked by Peter; United States

CNN Comment Policy: CNN encourages you to add a comment to this discussion. You may not post any unlawful, threatening, defamatory, obscene, pornographic or other material that would violate the law. All comments should be relevant to the topic and remain respectful of other authors and commenters. You are solely responsible for your own comments, the consequences of posting those comments, and the consequences of any reliance by you on the comments of others. By submitting your comment, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your comment(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statement.

The information contained on this page does not and is not intended to convey medical advice. CNN is not responsible for any actions or inaction on your part based on the information that is presented here. Please consult a physician or medical professional for personal medical advice or treatment.