You can’t force the body to absorb more water than it needs

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

11 February 2018

There is a new craze in town: water! Nowadays, people are drinking so much of it that I am beginning to suspect it is the reason the Ndakaini reservoir is drying up. The eight-glasses daily rule has seen a new awakening. Some are now going on a “water-rich” diet in the hope of losing weight.

This got me wondering and I did some digging. I found that the eight-glasses-per-day rule started in 1945. Yes; 73 years ago! I don’t think there is a lot of medical ideas from 1945 that are still in use today, but this one has refused to go away.

In 1945, the American Food and Nutrition Board noted that a person needs about 2.5 litres of water per day. Unfortunately, the next sentence after “…2.5 litres per day” has been ignored during the past seven decades. It said: “Most of this is contained in prepared food”. In other words, you don’t have to force-feed yourself with water since you get a lot of it from the food you eat.

As an experiment, I bought some lunch from the supermarket recently and checked the weight of each item (thankfully, it is sold by the kilo). I took 215g of fried beef, 270g steamed rice and 190g of mixed vegetables. I admit: that’s quite a heavy mealy!

Now beef is about 75% water; rice about 85% and vegetable 95%. So, my lunch contained 161g of water from the beef, 230g from the rice and 180g from the veggies. In total, I took in 571g of water from that heavy lunch.

Luckily, water is a special substance: it has a density one gramme per millilitre. So, 571g is equal to 571ml; that is, slightly more than a half a litre.

Looking at those numbers, it is easy to understand why some animals (like gorillas, for example) can go through their entire life without ever drinking any water! They get what they need from the leafy vegetables that they eat.

Well, after my heavy lunch, I felt thirsty and downed it with a half-litre soda. These contain about 85% water (the rest being mostly sugar). That drink pumped another 425ml of water into my body. The total intake from just one meal was 571 + 425 = 996ml – just shy of one litre.

Now my day usually starts with two mugs of tea and some bread (about 600ml water) and I take another two mugs at sunset (another 600ml water) – I strongly suspect that one of my ancestors must have been a Luhya!

Add another, say, 500ml from the supper food and my daily intake will be 2,696ml or 2.7L – just what the doctor ordered!

All in all, we should heed what Mohammed Abduba Dida advised during the 2013 presidential debate: “Eat only when you are hungry and drink only when you are thirsty”. After all, you can’t force the body to absorb more water than it needs: when you take excessive water, you will urinate more often!