Basically, water is the most abundant and essential component or macronutrient in the human body. It comprises, on average, about 60 percent of total body weight for young adults and about 50 percent for the elderly. Various body components account for different percentages of the body’s water content; generally, water constitutes 65 to 75 percent of muscle weight and 50 percent of body fat weight. The proportion of body water is generally smaller in females, the elderly, and the obese because of the smaller portion of muscle mass in these populations.We must know that the human body cannot store water; therefore, fluid must be replaced and kept in balance daily. Body water turnover rate is estimated to be 4 percent of total body weight to maintain normal body functions, which include excretion of body waste and evaporation from the lungs and skin. Recommendations for adequate water intake by adults are generally based upon several factors: humidity, temperature, altitude, exercise status, and use of diuretic medications.
So here are some recommendations for water intake. For adults whose energy expenditure and environmental exposure are average, the Food and Nutrition Board recommends 1 ml of water per kilocalorie expenditure (or, at 237 ml per 8 fluid ounces, 4.2 glasses per 2,000 kilocalories) as a general guideline for total water consumption. Thus, they recommends a total fluid intake of 30 ml/kg body weight (or 0.06 glasses per pound of body weight) and with a minimum of 1,500 ml (6.3 glasses) per day. We use this criterion to assess the adequacy of water intake.














