With much of the UK under a red warning for extreme heat and temperatures potentially reaching 40°C, staying hydrated is critical. However, many people struggle to differentiate between ordinary thirst and dehydration, which can be a dangerous oversight.
Hidden Signs of Dehydration
James Morehen, sports nutritionist and hydration expert at electrolyte brand Vidrate, explains that dehydration symptoms are often subtle. “Dehydration signs aren’t always obvious; they can show up as a headache or difficulty concentrating,” he says. “This can be mistaken for tiredness or screen fatigue, but if you experience either during hot weather, it can be an early sign your body needs more fluids.”
Cravings for salty or sugary foods may also indicate dehydration. Morehen notes: “When fluid levels drop, it can lead to fatigue, which the body may interpret as hunger.” Another overlooked sign is persistent bad breath: “When you’re not drinking enough fluids, your body produces less saliva, which plays a key role in washing away bacteria in the mouth. As bacteria build up, it can lead to an unpleasant odour.”
Thirst vs Dehydration: What’s the Difference?
Thirst is actually a late indicator of dehydration. By the time you feel thirsty, your body is already dehydrated. Morehen advises regular sips of water throughout the day to prevent this. “Drinking a full glass of water when you wake up and before you go to bed is one of the best things you can do during hot weather. Your morning glass helps to rehydrate after a night of sweating, and a glass before bed can help regulate body temperature – just leave a gap of 30 to 45 minutes before sleep to avoid a disrupted night.”
How Much Water Should You Drink?
The general recommendation is six to eight glasses of water per day, but during a heatwave, this can increase to around three litres, especially if you are active or spending time outdoors. A simple way to check hydration levels is by monitoring urine colour: aim for a pale-yellow colour. Darker urine suggests you need to drink more water.
