Water is important for regulating body temperature, cushioning your joints, strengthening your muscles, providing moisture for your skin and other tissues, and for carrying nutrients to your cells. The human body is more than 50 percent water, although the exact percentage varies, based on a number of factors, including gender, age and body composition.
Average Water Weight in Women's Bodies
Women tend to have a lower percentage of water weight than men, with an average of 52 to 55 percent, compared to an average of 60 percent for men. Different parts of your body have different percentages of water. For example, your lungs are about 83 percent water; your kidneys and muscles are about 79 percent water; and your heart and brain are about 73 percent water. Surprisingly, 31 percent of your bones also consist of water.
The Effect of Age
As people get older, they tend to have a lower percentage of body water. For example, a baby has about 75 percent body water, which drops to about 65 percent by 1 year of age. While adult women have about 55 percent body water, elderly people typically have only about 50 percent body water. This is partially because as people age, they lose muscle mass. Every 10 years after age 30, adults lose from 3 to 8 percent of their muscle, according to a study published in Current Opinions in Clinical Nutrition and Metabolic Care in 2012. Getting regular exercise -- especially strength training -- and eating about 25 to 30 grams of protein per meal can help limit muscle loss and reductions in body water as you age.
The Effects of Body Composition
Muscle contains more water than fat, so the higher your percentage of body fat, the lower your percentage of water weight. This is why women tend to have a lower percentage of body water than men, because women typically have a higher percentage of body fat than men. An overweight person may have only 45 percent of water in his body, and a very obese person with about 57 percent body fat would have a body water percentage of as little as 37 percent.
Maintaining Proper Water Balance
Your body is pretty good at balancing the volume of water you take in versus the volume you lose via your skin, breath, urine and sweat. You still need to do your part, by drinking sufficient amounts of water during the day. For most people, this amounts to between 8 and 12 cups of water each day. If the weather is very hot or if you exercise a lot, you may need even more. Foods such as soups, as well as fruits and vegetables, also contribute to your water intake, so try to include at least 5 servings per day.
If you don't drink enough water, your body will retain more water than usual, causing bloating and water weight gain. This is to help minimize the risk of dehydration. Once you drink enough water to make up for any deficiencies, your body will release the extra stored water. Consuming a high percentage of carbohydrates, getting a lot of sodium in your diet and not getting enough exercise can also cause your body to retain extra water. These fluctuations in weight can be as much as 5 pounds from day to day.