Arguments rage over the eight glasses a day rule, with disputes over how much is needed to clear the kidneys of toxins and whether or not water helps curb the appetite. It depends on how high the ambient temperature is and how much you are exerting yourself. It’s also a myth that other liquids don’t count. It doesn’t have to be water. Even food contains more liquid than you might expect. Pizza is 40-49% water, for instance. The percentage of water we derive from food in the diet depends on where you live. In the US it’s 22%. In Greece, where people eat more fruit and vegetables it is much higher.
So the problem is a general lack of evidence that drinking more water makes any difference to your skin. We can’t say it definitely doesn’t work, but there’s no evidence that it does. Which leaves the question of how much water you should drink. Since it depends on the weather and what you are doing, then there is a very good internal guideline we all have that can help. And that’s thirst.
You can hear more Medical Myths on Health Check on the BBC World Service.
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