Q: I’ve heard you should drink eight glasses of water a day. This seems like a lot. Is it really necessary?
A: No. Water is essential, but there’s no need to mega-water our bodies.
The body has a built-in way of controlling hydration and telling us how much we should drink. It’s called thirst.
An extensive review, published recently in the American Journal of Physiology, could not find medical evidence to support a need for those eight glasses a day. Drinking large amounts of water will not curb your hunger, “flush” away toxins or make your skin look moist and dewy. (Your skin will look dry if you become medically dehydrated, but no one is telling you to stop fluid intake. You will become thirsty long before you become dehydrated.)
In fact, there are good reasons not to force yourself to drink too much water. Over-hydration can lead to wetting accidents as your overfilled bladder contracts before you reach the bathroom.
And if you imbibe faster than your kidneys can process, you risk dilution of electrolytes and water intoxication, causing confusion and coma.
If you exercise strenuously, you should drink enough to make up for the sweating and energy expenditure that will follow. Feel free to drink a glass or two before you become thirsty, but don’t overload. If you are in the hot sun or extreme heat, you should also increase your fluid intake.
But under normal circumstances, you needn’t walk around with a designer bottle of water, gulping down more than you need to quench your thirst.
Dr. Reichman’s Bottom Line: Drink when you are thirsty. The dictum to drink eight glasses a day just doesn’t hold water.
Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," published by William Morrow, a division of .
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.