In recent years, water bottles have grown substantially, driven by health influencers advocating for increased water intake for benefits such as glowing skin, enhanced brain function, and improved athletic performance. But is it essential to drink excessive amounts of water daily? And can you actually drink too much? Tamara Hugh Butler, a physiologist with over 20 years of hydration research under her belt and the medical research director for California’s Western States Endurance Run—one of the toughest ultramarathons—aims to debunk prevalent hydration myths.

1. Myth: Everyone should drink at least 6 to 8 glasses of water daily.

The required water intake varies considerably among individuals and fluctuates day by day. Common advice suggests everyone needs to drink around two liters or eight glasses daily. However, there’s no universal rule. A person weighing 45 kg who remains seated all day doesn’t need the same amount as a 100 kg rugby player outdoors in the sun.

Your hydration needs should align with your daily fluid loss. Although we’re not aware of how much water we lose, it is our body’s signal for thirst. The brain constantly monitors blood composition, sensing when hydration is required, prompting thirst to prevent dehydration. Ignoring thirst will only amplify the urge to drink.

A common misconception is that thirst indicates severe dehydration; in reality, it simply signals that more water is needed. Personally, I only hydrate when thirsty, which aligns with the principle for 98% of people.

2. Myth: Plain water is superior to coffee for hydration.

As someone who doesn’t enjoy plain water, I often opt for coffee, watery soups, fruits, vegetables, and smoothies for hydration. I only drink plain water when outdoors and in need. You can attain adequate hydration from various beverages and water-rich foods.

Contrary to belief, coffee isn’t a significant diuretic; the need to urinate after drinking coffee results from the liquid itself, not the caffeine. On the other hand, alcohol does act as a diuretic, leading to increased urination after consumption.

3. Myth: Drinking water when not thirsty offers extra health benefits.

Consuming more water than necessary doesn’t contribute additional health benefits except possibly curbing appetite for weight management. Your body tightly regulates hydration levels, meaning excess intake only leads to more frequent urination. There is minimal scientific evidence supporting claims that excessive water intake enhances skin health, alleviates constipation, or boosts immunity.

However, while harmless in moderation, overhydration can be risky. My own research emerged following incidents of runners who passed away from excessive water consumption during marathons. Overdrinking can dilute sodium levels in the blood, resulting in hyponatremia, which may cause brain swelling and, in extreme cases, death.

Research indicates that consuming 3 to 4 liters of water within an hour can lead to symptoms of hyponatremia, including headaches, nausea, and bloating.

4. Myth: Sports drinks are essential for rehydration during exercise.

Many believe sports drinks are necessary for hydration during physical activity due to the electrolytes like sodium and potassium they contain, which replace those lost through sweat. However, studies reveal that these extra electrolytes are typically only needed for prolonged, intense exercises, such as running for 17 hours in extreme heat. Even with regular workouts lasting a couple of hours, the electrolyte loss can generally be compensated by regular meals afterward. While sports drinks can be beneficial for carbohydrate replenishment during intense exercise, most individuals do not require them.

As reported by Alice Klein