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💧 8 glasses of water a day – debunked

💧 8 glasses of water a day – debunked

The secrets of hydration, and recommendations for daily water intake.

HealthHack
January 28, 2024

Happy Sunday!

Today, we’re exploring a popular hydration myth, and seeing how much truth it really holds.

📊 HealthHack Poll of the Week 📊

Last week, we asked about your balance between sitting versus being active, and the most votes went to:

More sitting, but make time for movement.

This week, with our focus on hydration, we’d love to know:

How much water do you typically drink every day?

Cast your vote for your top choice, and drop a comment in the “Additional Feedback” box on the poll page to share more!

Debunking the 8-Glass Myth and Personalizing Your Water Intake 🚰

“Drink eight glasses of water a day.”

We’ve all heard this saying, but where does it come from, and how much truth does it hold?

Today’s deep dive unravels the science of hydration, challenges the 8-glass rule, and helps uncover how much water we really need.

The Origin and Oversimplification of the 8-Glass Rule

The famous “eight glasses a day” recommendation is rooted more in guideline than in scientific evidence.

It’s believed to originate from a 1945 Food and Nutrition Board suggestion that people should consume 2.5 liters of water a day, which fills about 8 glasses.

The problem with this suggestion?

First, it wasn’t based on research.

And second, this guideline suggested that most of this intake could come from food!

So, with that out of the way, let’s dig into how much water you really need to stay hydrated and healthy.

To start, here’s what today’s experts suggest when it comes to our hydration needs.

The National Academies of Sciences, Engineering, and Medicine provide clearer recommendations:

~3.7 liters (125 ounces) of total water per day for men
~2.7 liters (91 ounces) of total water per day for women

These amounts include water from beverages and food, with as much as 20% coming from your food!

Yet, even with those clearer recommendations in mind…

A consistent daily amount doesn't account for the nuance of individual hydration needs.

Everyone’s hydration needs are unique, and impacted by many factors.

In fact, your daily water needs can change quite substantially.

Some of the factors that influence your needs include:

Activity
- Higher levels of physical activity leads to increased water needs due to greater sweat loss

Climate
- Hot, humid, or dry climates, and high altitude, can increase your body's need for water, via increased perspiration and quicker dehydration

Health Status
- Pregnancy, kidney stones, urinary tract infections, and diabetes can all result in increased water needs
Diet
- Diets high in sodium and caffeine, or low in fruits and vegetables can also increase your hydration needs
Season
- You may also need more water during hotter times of the year

All that being said…

It’s not just about drinking the same amount every day of your life…

But more about naturally adjusting levels to what your body needs on a day to day, and season to season basis.

One important aspect of this is paying attention to your body’s hydration signals.

Some critical indicators that you’re starting to feel dehydrated include:

Dark-colored urine, urinating less frequently
Fatigue, or feeling weak
Irritability
Dizziness
Headaches
Muscle cramps in arms or legs
Dry mouth
Confusion, decreased cognitive function

While severe dehydration is rare, mild to moderate dehydration can affect mood, memory, and energy levels.

Now, in addition to protecting us from those symptoms…

Proper hydration has so many incredible benefits for us.

Adequate hydration is vital for numerous body functions…

It helps maintain blood volume and viscosity in the circulatory system, ensuring nutrients and oxygen circulate efficiently.

In the digestive system, water aids digestion and helps prevent constipation.

It’s also good for joint and skin health, maintaining elasticity, and helps clear toxins out of our body.

Additionally, drinking enough water promotes healthy aging — and even a longer life!

A recent NIH study conducted over 25 years revealed a link between higher serum sodium levels (associated with lower fluid intake) and an increased risk of chronic conditions and accelerated biological aging.

Now, while water is still the hydration king…

Staying hydrated doesn’t just have to come from water.

Foods like cucumbers, celery, lettuce, fruits, soups, and more can contribute significantly to your daily water intake.

And, despite common misconceptions, coffee and other caffeinated beverages can help hydrate you, too.

While caffeine does have a mild diuretic effect, it doesn’t offset hydration benefits.

So, how much water do we really need?

Going off the most recent recommended amounts, these numbers below are a safe bet to start with:

~3.7 liters (125 ounces) of total water per day for men
~2.7 liters (91 ounces) of total water per day for women

Just remember that our needs can change with different environments, choices, and seasons of life.

So — make sure to listen to your body, adjust your needs as necessary, and enjoy the gift of water for optimal health and performance.