Fluid: How much and what counts? When it comes to fluid, there are many conflicting messages, as with other nutritional messages. How much should I drink? Do tea and coffee count? What about alcohol?
How much? – If you look on the NHS Choices website for the official UK guidance, you will see the advice to drink around 8-10 cups a day. This is based on cups or glasses which are 200ml each. This equates to 1600-2000ml per day of drinks in total. In clinical settings, we use a calculation based on body weight. This gives a total fluid requirement, which includes fluid obtained both from drinks and from foods (e.g, milk on cereal, fluid content of yoghurt). It stands to reason that a heavier person will require more fluid to hydrate their additional mass. To calculate this, simply multiply your weight (in kg) by 35 (or by 30 if you are over 65 years old). If you weigh 70kg, then your fluid requirement is 2450mls, so drinking around 2000ml (2 litres) as drinks sounds about right. However if you weigh 100kg (approx 16 stone), your total requirements will be 3500mls, meaning you will need to drink closer to 3 litres each day. Most people will obtain around 500mls fluid from foods (think fruit, vegetables, yoghurt, soups…). Your requirements will be higher during warm/hot weather, if you’re doing exercise/training and if you have a fever. It’s difficult to put a figure on this as it varies per individual. Remember that once you feel thirsty, you’re probably already dehydrated, so it’s best to get into the habit of drinking fluids regularly throughout the day.
What counts? – contrary to what the media says, it’s not just water that counts! Tea and coffee count, along with fizzy drinks, milky drinks, fruit juices, squash, ice lollies and mocktails. Obviously some if these drinks may be high in sugar and are not the best for your health… But they still count as fluids. Water is healthiest choice because it has no calories and is great for your teeth. Unfortunately alcohol doesn’t count… but you can still count your mixer! As mentioned already, the fluid content on foods can be taken into account if using your total fluid requirement based on your weight. As a general rule of thumb, you can count 50% of their weight for foods like fruit, soups, yoghurts, instant whip and rice pudding. E.g. You can count a 150g pot of yoghurt as 75mls fluid.
Enjoy the summer and drink responsibly!