Don't worry - there's no need to down two litres of water at once. The best way to keep hydrated is to keep topping up throughout the day. A lot of your water intake comes from fresh fruit, vegetables, juices, and even tea. If you're a coffee fan, remember it's a diuretic and follow each cup with a glass of water to minimise dehydration. Make sure you take your water bottle with you to the gym, and if you go out drinking, try to switch between alcohol and water throughout the night. If you forget (nobody's perfect), at least have a large glass of water before bed.
You’ve probably heard that you need two litres of water each day. This is a rough guideline, based on the average man. Hydration needs vary from person to person, depending on height, weight, life style, diet and climate. The average person loses roughly one litre of water per day through breathing and one litre through urinating. If you exercise, you’ll sweat more than usual – you can work out how much more you’ll need to drink by using a sweat-rate calculator.
Water is crucial to helping your body maintain basic functions, from breathing to brain function. To break it down, your body is between 53% and 65% water (the people with 53% water tend to have more body fat.) Your brain is 70% water and your lungs are even more fluid, at 90%. Without water, you’ll start to notice things like bad breath, dry skin, tiredness, fogginess and sugar cravings, and chronic dehydration can even result in kidney stones and bowel disorders. Signs of dehydration include a dry mouth, headaches, dizziness and low blood pressure.