Do you need electrolytes? Will tea cool you down? Is it safe to drink beer? How to stay hydrated in a heatwave
The hotter it gets, the faster our bodies lose water. Obviously, we need to replace it – but is anything better than plain H₂O? And
The hotter it gets, the faster our bodies lose water. Obviously, we need to replace it – but is anything better than plain H₂O? And does timing matter? Here’s what the science says Hydration is important. In temperatures like those we’re increasingly seeing in much of the world, sweating can be the only way for our bodies to cool down, and our thirst isn’t always the best indicator of how much water we’ve lost or need. The consequences of not being sufficiently hydrated as temperatures creep towards the 40s can be severe, and can kick in much faster than most people realise.
The good news is that remembering to drink plenty of water at regular intervals throughout the day will be enough for most people to avoid the worst. But if you’d like to understand why dehydration is so dangerous, whether you really need extra electrolytes, or if a cup of tea really can cool you down, read on. To start with, it’s helpful to understand that our bodies are producing heat – and therefore losing water – all the time. “All the cells in our body are constantly using fuel for energy for various different processes, whether that’s movement or just staying alive,” says Dr Lewis James, a lecturer in sport, exercise and health sciences at Loughborough University.
“About 75 to 80% of the energy that we use appears as heat.” If we didn’t have any way of dissipating this heat, then even lying on the couch would see your body temperature rise about 1.3C in a single hour (already enough to make you noticeably feverish) – but of course, we do. Normally, we lose a decent amount of heat through a combination of convection and radiation: the blood vessels in our skin dilate, allowing the blood to be cooled by the outside air. The problem is that when the external temperature goes up, this process becomes less effective and eventually stops working altogether.
At this point, our main way of losing heat is through sweating: our bodies produce tiny droplets of warm water mixed with trace minerals, which (usually) evaporate on contact with the air, drawing heat away from the skin in the process. And as we rely more on sweating, it’s increasingly important to replace the fluids our bodies are losing. Continue reading...
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