Water is perhaps the most understated of all nutrients. Carbohydrates, proteins and fats, unlike water, are always associated with calories, weight or taste. They have a way of making their presence felt. But all of these, as well as vitamins and minerals, depend entirely on water, a tasteless, zero-calorie fluid, to function. A person can do without food for days and even weeks, but one cannot survive for long without water.
With as much as 60% of an adult’s body weight being water, it goes without saying that water is more than just a way to quench thirst. From lubricating and cushioning joints such as knees, wrists and shoulders, to moistening the inside of the eyes and lungs, transporting nutrients to muscles, bones and the brain, getting rid of wastes and toxins, maintaining body temperature and blood volume, water works at every step in the business of living.
Adequate consumption of water is clearly a priority if you want to remain healthy. Remember, sub-optimal water consumption causes dehydration, which can be crippling. Dehydration impairs metabolic processes, is responsible for lower energy levels, leads to excess body fat, poor muscle tone, digestive problems and the poor functioning of many organs, including the brain, joint and muscle soreness and, ironically, even water retention.
How much of our water intake comes from other foods? Not much. Though many of you may be consuming fluids and fruits with high water content—milk and fruits such as watermelon have 90% water content; bananas, potatoes and cheese have 75% water content—all said and done, fluid needs are best met by drinking water rather than from other foods. Coffees, teas and sodas are poor substitutes for water, and alcohol and caffeine act as diuretics. Extracting water from a fruit juice, tea or milk becomes an added task for the body and delays the access to water.
An individual’s water needs are difficult to establish because they vary according to age, environment, humidity and activity. On the one hand, the six cups of fluid in an hour that a marathon runner can lose can drive him to seek water urgently to moisten his parched throat. On the other hand, a senior citizen can get easily dehydrated pottering over everyday work because his brain isn’t sensitive any more to the thirst response.
Generally speaking, 100ml, or half a glass, is required for every 100 calories that you expend. In other words, you need around one glass for every 200 calories expended. For a woman, your basal metabolic rate, or BMR (which determines the minimum number of calories you need to live), should be 23 multiplied by the weight in kg; for a man it would be 24 multiplied by the weight in kg. Add 500-1,000 calories for activity—500 calories are better for the less active and 1,000 for those with higher activity levels—and you have your daily minimum calorie requirement.
Fill it up: Guys, get your 13 glasses of H2O each day.
For instance, for a man who is moderately active and weighs 78kg, the BMR is 78 x 24, which is 1,872, or approximately 1,800 calories as a minimum, plus 800 calories for moderate activity. This totals to 2,600 calories. Divide by 200 and you would get 13 glasses or approx. 2.5 litres that you should consume per day.
How do you ensure adequate water intake?
• Calculate how much water you need according to your weight and activity. Generally speaking, 13 glasses a day is good for men and nine glasses for women.
• Drink water at regular intervals through the day. If you need to drink 10 glasses then have two when you wake up, three during exercise and the rest half an hour before all meals. If having chilled nimbu paani (lemonade) helps you drink more water, by all means go ahead, but don’t add excess sugar or salt.
• Remember, if you are well hydrated the frequency of urination will be at regular intervals—every 2 hours or so. Longer periods of abstinence mean that you need to increase your water intake. You must excrete 500ml, or 2 cups, of water as urine daily to rid your body of toxic waste.
• If you are an athlete or work out hard and sweat a lot, you have special needs for water. The main reason for drinking water is to replace sweating. You need to sweat to cool the body on hot and humid days to maintain the body temperature. You need to drink water at regular intervals.
• If you are a senior citizen, you need to make drinking water at regular intervals a habit. Don’t rely only on the thirst signal.
• Drinking plenty of water also helps prevent bladder cancer by diluting urine and reducing holding time.
Madhuri Ruia is a nutritionist and Pilates expert. She runs InteGym in Mumbai, which advocates workouts with healthy diets.
Write to Madhuri at firstname.lastname@example.org