Water, water, everywhere

Water is one of our most precious commodities and it’s essential to life. But how do you know if you’re drinking the right amount?

Our bodies contain a lot of water. Women are around 50 to 55 per cent water, while men are around 60 per cent. The difference is because women generally have a higher ratio of fat to muscle than men, and lean muscle holds more water than fat does. Age also influences a body’s water volume – babies, for example, are 75 to 80 per cent water. And water percentages vary across the body, with human bones being 31 per cent water and the brain coming in with the highest volume, at 85 per cent. Most bodily functions depend on it. Water lubricates your joints and regulates your temperature, while making digestion and waste elimination possible. Humans can survive without food for several weeks, but without fluids, most people would go downhill fast after three days. It’s no surprise, then, that the internet is awash with advice and tips for drinking the right amount. And there are suggestions that good hydration will help with everything from focus to weight loss. But what does the science say?

Each to their own

You may intuitively know that staying well-hydrated makes you feel healthier and happier. That’s backed up scientifically by a study published in 2023, during which more than 15,000 adults were monitored over 25 years, with the level of salt in their blood being measured at regular intervals. Its take-home message? Optimal hydration, which reduces your sodium concentration, means you’re more likely to stay healthy and less likely to develop chronic conditions, including heart and lung disease. The study concluded that adults who stay properly hydrated also appear to live longer compared to those who don’t get sufficient fluids.

So, what about the other side of the coin, when you aren’t properly hydrated? The early signs of dehydration, says Nichola Ludlam-Raine, a registered dietitian and author of How Not to Eat Ultra-Processed Foods, can include ‘tiredness, headaches, poor concentration, dizziness and constipation’. At a more severe level, dehydration can affect ‘kidney function, blood pressure and heart health’, she adds.