In his BBC Radio Four series, Just One Thing, Dr Michael Mosley gives tips on simple actions that can immediately begin to improve our health: just one thing can improve your mental and physical health and, in one episode, he said that one thing is drinking water with every meal.
Opening the programme, he said: “It’s lunch time and I am about to do just one thing that can boost my concentration, boost my energy levels and keep my skin healthy. I’m drinking a glass of water.”
There are many confusing messages about how much we should be drinking, he said, commenting that sticking to tea, coffee and soft drinks may not be a great idea.
So how much should we be drinking? Dr Mosley said: “Well for most of us all we need to do is have a glass of water with every meal. It’s that simple. Keeping hydrated can improve attention and problem solving, it can improve your mood, help you keep calm and alert, improve your skin, and even help you lose weight.”
Keeping properly hydrated can make a big difference to our brains, our physical performance and our overall health. The human body 60% water but the brain is made up of 90% water. We need water to digest food and help our kidneys to flush out waste. It is important to replace the water we lose. Even mild dehydration can cause 1-2% loss of our body’s water and this can impair cognitive function, pointed out Dr Mosley. He added: “Studies have shown that drinking water can improve short term memory and working memory and drinking water can significantly reduce regular headaches. If you are playing football, it could improve your performance. And last but not least, it could help with weight loss.” He cited a scientific study which showed that a group dinking half a litre of water before each meal ended up consuming fewer calories and lost the most weight compared with another control group.
For those who find the idea of drinking a lot of water rather daunting he was reassuring: “If you love water, go ahead,” he said, “but there really is no need to go mad. For most of us just adding an extra glass [of water] with every meal is probably enough. A lot of us aren’t even doing that. Relying on tea, coffee and other caffeinated drinks is okay but although the first few cups will hydrate you, research suggests there is a tipping point where these drinks start to become a diuretic and you actually lose more water than you gain.”
He turned to an expert, Dr Stuart Galloway, Professor in Exercise Physiology from the University of Stirling, to clarify any confusion about the important role of water asking him, “What is water doing to your body and brain?” Dr Galloway said: “We need water to undertake a number of processes and because we are constantly losing water throughout the day through breathing, sweating, urine loss, we need to replace that with water from drinks and from our foods. If we don’t’ replace the fluid we can have impaired mental performance, impaired physical performance and feelings of fatigue, for example.” He cited what he described as an interesting study in older adults where mortality was found to be greater if they were admitted to hospital in a dehydrated state. “The consequences of having inadequate water intake can be very severe to mild or moderate.”
Dr Galloway said the European fluid intake guideline is for around 2 litres a day of fluid (not necessarily water) for a man and 1.6 litres for a woman. He offered some good advice: “Your urine colour along with the number of times you go to urinate is a good guide. Often people fall a bit short of the recommended intake because they fall short of drinking just plain water so a glass of water with your meal is a good way of ensuring you meet your daily fluid intake targets.”
So if the number of times you go to the loo is a good guide, what is the advice? Both Dr Galloway and Dr Mosley said that if you are going for a ‘wee’ 5-7 times a day you are probably drinking the right amount of fluid. If you are only going 3-4 times a day, you’re probably not drinking enough; and if you’re going 7-8 times a day you’re probably drinking too much.
Dr Galloway said that milk is also excellent for rehydration but agreed that milk contains a significant amount of calories. He said “So you don’t want to do that [drink milk] if you want to lose weight but it can be a good idea post-exercise.”
He added that with regard to caffeinated beverages such as coffee and tea you can include these in a balanced diet. “You can have [coffee] as part of your hydration goal. It is a bit unclear as to when it starts to have a diuretic effect but it seems to be about 400-500 mgs of caffeine which is equivalent to about 4-5 reasonably strong coffees.”
It has been suggested by some pundits that the best way to measure whether you need to drink is whether you are thirsty. Dr Mosley asked if that was an adequate guide. The short answer was ‘no’.
Dr Galloway explained that: “In humans when you feel thirsty you are already down about 1-2% loss of your total body mass as water and that is quite important because as little as 2% loss can affect some of your abilities such as physical endurance abilities and mental abilities, but it can also affect your mood state – whether you feel fatigued for example.”
It’s all a question of making drinking water part of your daily routine, they concluded.
Dr Mosley said: “Making sure I drink a glass of water with every meal has topped me up and I think I can focus a bit better. Just one thing you can do to cut down on headaches, boost your sports performance, and help you think more clearly. This is just one thing you could incorporate into your daily routine which really could benefit your body and life. Cheers.”
Drinking water with every meal is just one thing you can do to improve health
Top tips from the experts
- Make sure you urinate 5-7 times a day
- Drink before you are thirsty
- Don’t let your fluid levels drop as even a 2% loss can impair mental and physical performance
- Caffeinated drinks are okay in limited quantities but then have a diuretic, not a re-hydrating, effect. Milk is good unless you are trying to lose weight in which case water is best.