Do water intake recommendations change with weight?

DEAR DR. GOTT: The only answer to my question that I find in written materials or on Internet sites is always the same: eight glasses of water per day. That across-the-board answer doesn’t seem to take weight into account. A friend of mine weighs 280 pounds, and I weigh 140. Having twice the flesh that I do, shouldn’t he be consuming, on average, about twice the water that I should? Is there some general equation for average daily water consumption that is weight-dependent?

DEAR READER: People are too hung up on drinking a specific amount of water each day. The rule used to be eight 8-ounce glasses every day. Now there is some debate about that. My recommendation is typically to drink as much or as little as your thirst dictates; however, that is not specific enough for some people who want, it seems, a blueprint for healthy living down to the number of glasses of water to drink or the number of times a day they need to defecate. It’s just plain silly. Everyone is different, so what each person requires to be healthy is different. What is normal for me is not normal for you.

With that in mind, and to the best of my knowledge, there is no weight-to-water equation. Drink if you’re thirsty; don’t if you’re not. If that isn’t good enough, try drinking enough water so that, when you urinate, it is a pale yellow color. This will ensure that you are taking in enough water to aid the kidneys in flushing toxins and waste from the body and maintaining a normal electrolyte balance. (Certain vitamins or medications can influence the color of the urine.)

Keep in mind that it is possible to drink too much water. This will cause a potentially life-threatening condition known as water intoxication. It occurs when a person drinks an excessive amount of water in a short span of time (usually over a few hours), resulting in an electrolyte imbalance that causes the water in the blood to migrate to cells. These cells then swell. If this occurs in the brain, there is no place for the cells to stretch and can result in brain damage, seizures, coma, respiratory distress and even death.

Are eight glasses of water necessary?

DEAR DR. GOTT: Please explain where the idea of drinking “eight glasses of water a day” comes from. I have found no logical explanation.

DEAR READER: Water makes up almost 60 percent of a person’s body weight and is vital for our well-being. It flushes toxins from the system, carries nutrients to all cells, and keeps us properly hydrated. So how much is too much?

There is no scientific basis for the amount of fluids a person should ingest. Eight glasses of water daily is simply an easy rule of thumb. The recommendation for all fluid intake is 9 cups for women and 13 cups for men. This includes coffee, tea, milk, breakfast juices, soup broth and so forth. [Read more...]