"Think of water as a nutrient your body needs that is present in liquids, plain water, and foods. All of these are essential daily to replace the large amounts of water lost each day," says Joan Koelemay, RD, dietitian for the Beverage Institute, an industry group.
Kaiser Permanente nephrologist Steven Guest, MD, agrees: "Fluid losses occur continuously, from skin evaporation, breathing, urine, and stool, and these losses must be replaced daily for good health," he says.
When your water intake does not equal your output, you can become dehydrated. Fluid losses are accentuated in warmer climates, during strenuous exercise, in high altitudes, and in older adults, whose sense of thirst may not be as sharp.
1. Drinking Water Helps Maintain the Balance of Body Fluids. Your body is composed of about 60% water. The functions of these bodily fluids include digestion, absorption, circulation, creation of saliva, transportation of nutrients, and maintenance of body temperature
2. Water Can Help Control Calories. For years, dieters have been drinking lots of water as a weight loss strategy. While water doesn't have any magical effect on weight loss, substituting it for higher calorie beverages can certainly help.
3. Water Helps Energize Muscles. Cells that don't maintain their balance of fluids and electrolytes shrivel, which can result in muscle fatigue. "When muscle cells don't have adequate fluids, they don't work as well and performance can suffer.
5. Water Helps Your Kidneys. Body fluids transport waste products in and out of cells. The main toxin in the body is blood urea nitrogen, a water-soluble waste that is able to pass through the kidneys to be excreted in the urine, explains Guest. "Your kidneys do an amazing job of cleansing and ridding your body of toxins as long as your intake of fluids is adequate.
6. Water Helps Maintain Normal Bowel Function. Adequate hydration keeps things flowing along your gastrointestinal tract and prevents constipation. When you don't get enough fluid, the colon pulls water from stools to maintain hydration -- and the result is constipation.