The Facts On Hydration And Why They Matter

by Andrew SchaefferNov 12, 2016App, Nutrition0 comments

Hydration Recommendations Hydration is a keyword in fitness. You’ll hear that it can help you do everything from lose weight to perform better in your workout. What are the facts about hydration and dehydration and how can you get it right for your health and fitness, and for the world?

The 8 Cup Rule

You may have heard that you should drink 8 cups of water per day. This is a common guideline but it isn’t based on any research.¹ The main reason that this rule sticks, according to the Mayo Clinic, is that it is easy to remember.²

Part of the problem here is that hydration is very individual and hard to nail down. Short of actual dehydration, which can cause problems if severe enough, there is simply no useful frame of reference. For example, consider that fat cells and muscle cells contain significantly different amounts of water. Two individuals of the same height and weight but with different muscle to fat ratios will show different levels of body water. Is one of them dehydrated?

The 2% Rule

A common statistic is that dehydration which results in a 2% drop in body mass is enough to impair performance. This is one of the pieces of information that has lead to the idea that everyone should drink plenty of water.

Research on this topic goes back almost 100 years and many studies from the 1960’s and 70’s are still regularly cited. But a lot of this early research deals with dehydration and athletic performance in hot environments. In the heat, an exercising body has a dual demand on blood flow. Muscles require more blood to perform and the skin requires more blood for cooling. This extra physiological stress can be a problem and dehydration makes it worse. This research has not been satisfactorily verified on non-athletes in normal conditions, so it is a little questionable to apply it universally, which has caused some to challenge the validity of hydration recommendations.³

Clear Urine And Staying Hydrated

If hydration is difficult to determine and the effects of water loss unclear, what is one to do? One guideline recommends that you should have clear urine, but this doesn’t hold up. A healthy body is very good at maintaining its fluid balance, mostly through the thirst mechanism for intake and the kidneys for excretion. This ability of the body to efficiently and automatically regulate fluid balance suggests that clear urine, rather than being a sign of good hydration, is actually a sign of too much water intake. The body is simply flushing it out of the system.⁴

Does Drinking Water Help You Lose Weight?

This question is under-studied.⁵ When dealing with weight loss and weight gain, there are always multiple factors at play. For that reason, it can be difficult to ascertain the exact impact of any one intervention, especially over time.

That being said, it stands to reason that drinking water could have a postive effect on weight by either replacing caloric beverages or by altering eating habits. Sugary drinks in particular are recognized as a contributor to obesity⁶and may be implicated in other health problems like metabolic syndrome.⁷ For that reason, using water to crowd out other potentially unhealthy options is a good strategy. You should differentiate though between water itself causing weight loss and water leading to habit changes, which in turn cause weight loss.

What’s The Harm In Drinking Extra Water?

Probably nothing. Drinking too much water can have severe health consequences, including death, and should be respected, especially when drinking unusual amounts of water as one might when hydrating for a sporting event. However, under normal circumstances, the physiological risk is probably not of primary concern so if you want to get into hydrating more, few people would stand in your way.

Water And The Environment

There is a rather substantial environmental downside to overzealous hydration guidelines. Bottled water has been a growth industry for several decades⁸ with U.S. consumption now somewhere between 40 and 50 billion water bottles per year.⁹ All of that plastic waste has to go somewhere and only around 30% of it is being recycled. In short, over hydrating with bottled water has real downsides for the earth.¹⁰ Carrying your own, refillable water bottle is a great way to combat this problem.

Further, fresh water is a finite resource.¹¹ We do need to be mindful of how we use it.

What Should I Do? – Conclusion

To sum up, some of the mythology that has grown around hydration should be clarified. The fear of dehydration should not motivate behavior and excessive water intake without reason shouldn’t be the norm. Heavy water loss from physical activity (sweating), extreme heat, illness, age, and some other factors are sound reasons to increase your intake of water. Normal, everyday living on the other hand does not appear to call for 8 cups a day, clear urine, or constant sipping; the evidence simply does not support it. Instead, relying on your body’s built in thirst mechanism makes a lot of sense.

Remember that water comes with environmental ramifications as well. Fresh water is a finite resource and plastic bottles add up to a lot of environmental pollution, so it is worth considering how we use it. You can help to keep trash out of the environment, preserve fresh water resources, and even to bring fresh water to those who don’t have it, all by making sensible choices about how you approach your hydration.

How Water Really Affects Health And The Environment

Additional References

The Essentials of Sport and Exercise Nutrition. Precision Nutrition, 2010

The Essentials of Strength Training and Conditioning. 3rd ed. Champaign, Il: National Strength and Conditioning Association, 2008