Drink eight glasses of water a day. Coffee will make you dehydrated. Drinking extra water can help you lose weight. You’ve likely encountered these claims about water and hydration. Here’s what experts say about them:

Hydration Myths Debunked

Myth #1: You Need Eight Glasses a Day

Many believe drinking eight 8-ounce glasses of water daily is necessary. However, research fails to support this. While water is vital for body functions, like waste removal and temperature regulation, the suitable amount depends on various factors such as body size, activity level, temperature, and sweat loss.

Tamara Hew-Butler, an associate professor at Wayne State University, advises trusting your body’s signals. “If you get thirsty, drink water. If you’re not thirsty, you don’t need to drink,” she says.

While this general rule applies to most, older adults may have reduced sensitivity to thirst and might need to monitor intake more carefully. Additionally, those with medical conditions like kidney disease may benefit from extra water.

Myth #2: Caffeine Causes Dehydration

Another myth claims that caffeine is a diuretic that dehydrates you. Studies, including a 2014 clinical trial, suggest caffeinated drinks hydrate similarly to non-caffeinated ones when consumed in moderation.

Mindy Millard-Stafford from Georgia Tech explains that all fluids, including caffeinated beverages and foods, contribute to hydration.

Myth #3: Sports Drinks Are Essential

Some believe sports drinks are necessary to replace electrolytes lost during exercise. While they can replenish sodium, potassium, and chloride, food and other drinks can also suffice.

Humans have evolved to crave salt and minerals just as thirst prompts water intake. According to Yuki Oka at Caltech, our brain signals hunger for salt when needed.

Myth #4: Drinking Water Aids Weight Loss

Studies on water and weight loss yield mixed results. Some research indicates drinking water before meals may help some people eat less, but evidence is inconsistent.

Researchers note that replacing sugary beverages with water can assist in weight loss. A study showed a 2 to 2.5% weight reduction among participants who substituted sugary drinks with water.

Myth #5: Dark Urine Indicates Dehydration

While dark urine often suggests dehydration, it’s not entirely accurate. In a study by Hew-Butler, athletes with dark urine did not show dehydration when tested by blood.

Instead of solely relying on urine color, monitoring blood sodium concentration provides a clearer picture. For those not vigilant about thirst signals, keeping urine a light straw-yellow color may be a useful hydration gauge.

Finding the right balance in hydration is key: not too much, not too little.