Introduction

We’re in summer, a time of year when it’s especially important to monitor hydration in our bodies.

Did you know that our bodies are made up of around 60–70% water?

Of course, this percentage varies with age — when we’re younger, our water content is higher, and as we age, it gradually decreases.

An adult typically loses between 2,600ml and 3,100ml of water per day through urine (1,500ml), faeces (200ml), breathing (600ml), and perspiration (600ml). These losses are partially compensated through solid food intake (1,000ml) and the water produced during oxidative metabolism; the rest must be replaced by the fluids we drink.

Determining the exact amount of water a person should consume is tricky, as it depends on individual needs. However, it is estimated that 1,500ml to 2,000ml of fluids per day is ideal, and this may increase to 3 litres if requirements are higher.

By “fluids”, I primarily mean water, followed by juices, soft drinks and herbal teas — excluding milk, which is considered a food. One must be cautious with excessive consumption of sugary drinks and juices, as they contribute too much sugar and are not recommended for people who are overweight.

As for athletes, their fluid needs are much greater, especially those who train outdoors in high temperatures. In these cases, isotonic drinks can be useful, as they contain the same salt concentration as our bodies. This means they hydrate while also replacing lost electrolytes. But again, we’re talking about athletes — drinking isotonic drinks with meals is not recommended. Water should always be the first choice.

When should you drink water to stay properly hydrated in summer?

Thirst is a signal sent by the brain to tell us we need fluids.

By the time we feel thirsty, our body has already lost about 1% of its fluids, which means we’re already mildly dehydrated. That’s why it’s essential to be proactive and drink water before we actually feel thirsty.

Signs of dehydration include:

• Fatigue
• Dry mouth
• Weakness
• Even dizziness

It’s important to be especially mindful with the elderly, who often don’t feel thirsty, and with babies, who can’t ask for water and have higher fluid requirements. Children and pregnant women also need more fluids.

Something quite typical in summer is the increased consumption of alcoholic drinks. Alcohol dehydrates the body because it inhibits the action of vasopressin (ADH), an antidiuretic hormone that regulates water reabsorption through urine concentration.

As a result, we urinate more and not only lose water but also essential minerals and electrolytes. Even our brain is affected, which is why we get those familiar headaches the day after drinking alcohol.

Personally, water is my drink of choice, but I know that many people find drinking water boring or unappealing. One tip for them is to flavour it with a little stevia and/or erythritol and lemon juice to make it more enjoyable.

So don’t forget to stay well hydrated this summer, don’t wait until you’re thirsty, and protect yourself from the heat. You’ll feel much better — and your body will thank you.