Water in Balance
If someone asked you how much water you drink in a day, what’s your answer? Do you have an understanding of your individual fluid needs? As a dietitian, this is a common question I receive from clients and a big part of what I do in helping individuals improve their relationship with food. In this blog, I’ll explain some history on water, how much water is enough, signs of over and under hydrating, sources of hydration other than water, and how as a dietitian I provide personalized recommendations.
The history of bottled water
To provide some context to water and recommended needs, I wanted to start with a brief history. The trend of carrying water dates back to early wells and clay pots for transporting clean water home. In the early 1600s, the first commercial distribution of bottled water was implemented by the Holly Well bottling plant. In the 1700s and through the early 20th century, spring water was sold largely in the UK and America for recommended health benefits and improving certain illnesses. It was sold as therapeutic, more refreshing, and cleaner, less polluted than city centers’ tap water.
In the 1980s the creation of plastic allowed for cheaper bottling, coupled with the EPA in 1986 warning consumers of lead contamination in tap water. This further pushed the movement of water bottles, plastic, glass, and reusable, along with the fact that celebrities and upcoming films popularized them..
Leading into the 2000s, water bottles grew in popularity, for environmental and supposed health reasons. Companies like Brita sold their products with the claim that filtered water and spring water were healthier compared to tap water. Today, it’s common to see individuals carrying around water bottle brands that become trendy through social media, also influenced by medical providers, fitness personnel, and coaches pushing individuals to drink more water and bottles being an ideal way to remind one to drink all day. This water bottle trend can be helpful, but the message of more water, at times, may come from false claims such as water will cure x disease, drink more water to curb hunger, 64oz of water per day is required to be healthy, or caffeine does not count towards this 64oz.
How much water do I really need?
The 64 oz value or 8 x 8 glasses per day is a common, standard recommendation for water intake. However, when I get the question of “Is 64oz of water enough for me?”, I start by breaking down individual fluid needs, today’s Adequate Intake (AI) recommendations for water, and, most importantly, that not just water counts towards daily fluids.
In review of the research and organizational recommendations, an earlier AI for water, set by the National Academy of Medicine, was approximately nine 8oz glasses of fluids for women and 13 glasses for men (~1900mL or 1.9L/day and ~3100mL or 3.1L/day). This AI is for all fluids, not just the daily intake of water. The Academy of Nutrition and Dietetics per the same academy writes today’s AI for water is 11.5 glasses for women (~2700mL or 2.7L/day) and 15.5 glasses for men (~3700mL or 3.7L/day). Studies contributing to these recommendations appear to be observational rather than the clinical trial gold standard: today’s healthy adult individuals have been questioned on their daily consumption of all fluids, an average intake was found, and the AI for water for America’s general population was born. Another caveat to these recommendations is that there is inconclusive evidence that drinking this much fluids will reduce the risk of chronic diseases. For reference, here’s a helpful statement published by the Institute of Medicine, of the National Academies, in their book “Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate” (2005 edition):
“Water is the largest single constituent of the human body and is essential for cellular homeostasis and life. Total water intake includes drinking water, water in beverages, and water that is part of food. Although a low intake of total water has been associated with some chronic diseases, this evidence is insufficient to establish water intake recommendations as a means to reduce the risk of chronic diseases. Instead, an Adequate Intake (AI) for total water is set to prevent deleterious, primarily acute, effects of dehydration, which include metabolic and functional abnormalities.”
In short, 64oz is similar to the AI recommendations, and may be appropriate depending on your individual needs, but it should not be the standard for everyone, and surely not for just water.
As dietitians, a common algorithm to individualize fluid needs is to drink 1mL of fluids per calorie consumed. This better accounts for activity level, age, gender, stress states, height and weight. This is my preferred method, still with some variability, but stands for all fluids (again not just water).
Other recommendations I’ve seen and used for my clients involve replacing fluids during and post endurance exercise. Here are some examples, adopted from today’s research:
Use the sweat test for assessing total fluids lost over a 1 hour run at race pace. The practice is to weigh yourself pre and post run, dried off and in the same clothing each weigh in, and to consume 8oz of water for every pound lost. Also, fluids consumed on that run should be considered and added to the total ounces to rehydrate.
The ACSM Position Stand and The Advisory Statement by Noakes and the International Marathon Medical Directors Association recommend a baseline range of 400-800mL/h (13.4 - 26.7 fl oz./ hour or 1.6-3.3 glasses of water). The statement also suggests that this range is very individualized and weight, age, exercise intensity, duration of the endurance activity, and environmental temperature can alter this range. Simultaneously, it’s recommended to customize a sodium plan to reduce the risk of overhydration and hyponatremia, especially for high sweat rates and exercise for >2 hours.
What counts as meeting my daily fluid needs?
Fluids can be consumed through the following:
Water– filtered, tap, flat and carbonated, flavored, warm or cold
Sugar sweetened beverages
Electrolyte-rich fluids, ie sports drinks
Caffeinated beverages- tea, coffee, soda
Alcohol– this has its own recommendations per day for males and females, per the DGA
Foods high in water content– 20% of total fluids can be met through food
How do I know if I’m drinking enough or too much?
From all the resources reviewed for this post, one clear message is to seek a professional for individual hydration recommendations. However, there are some tell-tale signs to help understand if you're properly hydrated. First is urine: pale yellow indicates adequate hydration, where a darker, amber tinted yellow indicates lack of fluids. With this test do beware of the supplements and medications you are taking. Certain B vitamins like B12, Vitamin C, some prescribed and over the counter medications may affect urine color. Second is physical signs/symptoms. Headaches, muscle weakness, gastrointestinal discomfort, dizziness and lightheadedness, dry skin, cold intolerance, dry mouth, and fatigue are a few signs you’re needing to drink more fluids. Later symptoms of confusion and delirium can also occur if left untreated. Signs of overhydration are similar to dehydration.
Curious on how much water is right for you? Start by reaching out to one of us at Enhance Nutrition today. We are nutrition professionals who can help you meet your hydration needs as part of your overall health goals.
Resources used to develop this post:
National Academies of Sciences, Engineering, and Medicine; 2005; Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate; Washington, DC: The National Academies Press; DOI: 10.17226/10925.
Kenneth Vitale and Andrew Getzin; Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations; Published online 7 June, 2019; DOI: 10.3390/nu11061289