‘Drink Eight Glasses of Water a Day!’ You have probably read about this and heard this long and often enough to believe that it is the gospel truth for keeping your body adequately hydrated. However, drinking eight glasses of water a day is nothing more than a popularly propagated health myth.
Indeed, keeping your body duly hydrated contributes to your overall health and well-being, as every cell in your body needs fluids for proper functioning. Even slight dehydration can interfere with the body’s ability to function well and manifest itself in form symptoms such as light-headedness, irritability, and headaches.
It is, perhaps, this fear of dehydration that has led self-proclaimed health experts and overzealous fitness trainers to put a number on the daily water requirement of the human body. Be that as it may, it is not possible to generalize the water requirement of the entire human race. The 8-glasses-a-day is but a generalized figure that may or may not meet, or even exceed your body’s requisite water intake.
The genesis of this Myth
Health experts and doctors find themselves at a loss as to where the ‘eight glasses of water a day’ theory originated. A 2002 study titled, ‘Drink at least eight glasses of water a day. Really? Is there scientific evidence for “8×8”?’ tried to get to the bottom of this myth and traced its roots to a single paragraph in a 1945 report by the Food and Nutrition Board of the National Research Council in the US that states that adults should consume nearly 2.5 liters of water every day, which roughly equates to eight glasses of water.
However, the same report also noted that a large part of this water requirement is met by water content in the foods we consume and supplemented by beverages such as tea, coffee, milk, and even soft drinks. Somehow, the 2.5 liters figure stood out and gave way to the eight glasses of water a day theory.
If one looks at the World Health Organisation’s recommendation for water intake, it becomes amply clear that the amount of water needed by the body varies according to different physiological and demographic factors such as age, sex, location, climate, activity levels, and more.
For the sake of aggregation, the average total water intake has been pegged at 2.7 liters for women and 3.7 liters for men, ‘total’ is the keyword here.
This means that you do not need to drink 2.7 liters or 3.7 liters of water straight from the faucet. Our food intake meets about 20 percent of this value. Beverages such as fruit juices, soft drinks, milk, tea, and coffee also contribute toward a portion of the remaining 80 percent of the body’s water requirement.
In addition to this, the body’s water requirement may vary depending on individual lifestyle factors:
- People who exercise or play sports tend to lose more body fluids through sweat, and therefore, need more water to replenish the body cells.
- People living in hot and humid areas require additional fluid intake to avoid dehydration. The same is true for those residing in high altitude regions.
- Certain medical conditions, or temporary illnesses such as vomiting, diarrhea, and fever, also call for increased fluid intake, besides oral rehydration supplements.
- Expecting or lactating mothers need to consume more fluids than other women.
- Similarly, your body’s need for water also varies daily depending on your food intake. For example, if you eat watermelons, spinach, or cucumbers, all of which have heavy water content, on a particular day, the amount of water you need to drink on that day automatically goes down.
Your body gives you signs that you need to drink water long before dehydration sets in. The most practical rule of thumb is to keep a bottle of water handy and drink whenever you feel thirsty.