Registered dietitian Elisa Zied explores and debunks many such myths in a chat with The Early Show co-anchor Julie Chen Monday.
Zied, who's also a spokesperson for the American Dietetic Association, says No. 1 on the list is that we should drink eight glasses of water a day to stay healthy and hydrated.
"What we really need to be concerned about," Zied says, "is not so much our water intake in particular, but our total fluid intake. We get fluid from water; we get it from other beverages, coffee and tea, juice, milk, all kinds of beverages. We also get water in a lot of the foods we eat, especially fruits and vegetables.
"Plain water should make up half the total beverages you're consuming. Women need about 11 1/2 cups of fluid a day. Men need about 15 1/2 cups. That includes fluids from fruits and vegetable, soups, vegetable soups, cooked grains. All these foods contain a lot of water. …So, if you're drinking some lowfat milk, a little bit of fruit juice, coffee and tea, you can really meet your fluid needs.
"I would say at least five or six cups of water (a day) is a good rule of thumb. Then get the rest of your water from fluids and fruits and vegetables."
Asked if it's wise to just drink when you're thirsty, Zied responded, "For a lot of us, it's okay to use thirst as a guide for our level of hydration. But for many of us, as we get older, our thirst mechanism is a little bit blunted. So, it's very important to monitor your urine. It's not appealing to do that, but you really want to look for a light color. And if you exercise a lot, you might want to weigh yourself before and after and, if you lose weight, that means you need a little bit more water."
What about the notion that drinking caffeinated drinks actually dehydrates you, and so is counterproductive?
"Actually," answered Zied, "It's not really that true, according to a lot of studies. If you're a habitual coffee drinker, if you drink a lot of tea or sodas, or anything caffeinated, your body adapts and it doesn't lose as much water as it might if you suddenly drink caffeine when you're not used to it. So, if you're a habitual drinker, the coffee and tea that you drink and the sodas can contribute to your fluid needs every day."
Certain diets advocate having a big glass of water before you eat a meal, saying that will mean you're not as hungry. Does that work, or is that just another myth?
"Well," Zied observed, "if you're having water at the start of a meal and it's replacing something that's more caloric, another caloric beverage, that can help you decrease your calorie intake, which can promote weight loss. But the most important thing is to eat a lot of high-water foods, again, foods like fruits and vegetables, broth-based soups, salads. Things like these, studies have shown, have a lot of water and a lot of fiber and nutrients, with few calories. So if you load up on these foods, you can decrease your calorie intake, which can promote long-term weight loss."