The teams are headed to the Super Bowl, this time taking place in the famously hot and dry climate of Arizona. For any athlete, whether they’re playing on home turf in chillier temps or doing Pilates in arid weather, one of the most important things to keep on top of is hydration. But how much is enough? We posed this question to Craig Broeder, Ph.D., Founder and CEO of Exercising Nutritionally, LLC. Exercising Nutritionally provides research quality testing in body composition, sports performance testing, nutrition counseling, health assessments, and educational programs for preventive health.
Our thanks to Dr. Broeder for being this week’s guest blog writer!
Hydration – How Much Is Enough?
I am not sure when I was first told I should drink eight 8-ounce glasses of water a day. I think it was in one of my high school health classes, dating that guideline back 45 years for me. Have you ever wondered how that recommendation came about? Or, why we are told 64 ounces of water a day, rather than tea, coffee, juice or some type of sports drink? If I told you that as a person trained in biochemical nutrition and physiology that I seldom drink plain water ever and my own personal hydration status measurements are always normal, what would you now think about the recommendation to drink 64 ounces of plain water daily?
First and foremost, it is absolutely essential our bodies are well hydrated. Under normal conditions, 65- 75% of a human body is comprised of water. The body’s water content varies depending on your hydration strategy in context to
- activity level
- physical characteristics
Here’s an interesting fact about the human body: the leaner a person’s body is, the higher the total body water content (i.e., 70-75%), provided that person is properly rehydrating themselves. In stark contrast, an obese adult can have less than 45% total body water content. Without adequate body water, you cannot sweat properly in order to moderate heat. That is one reason why it is more difficult for over-weight men and women to comfortably exercise without getting extremely hot and uncomfortable.
How much fluid should we consume per day? First, drinking eight 8-ounce glasses of water a day is a recommendation that is not based on modern day scientific evidence. Heinz Valtin, MD published an article in the American Journal of Physiology (2002) after searching the scientific literature and found no scientific evidence to support this common recommendation. The most current recommendations come from the Institute of Medicine (IOM; ), which is a sub-division of the National Academy of Sciences. This group’s fluid intake recommendation is 91 ounces for women and 125 ounces for men. But, it is very important to understand that these recommendations includes all fluids (i.e., coffee, tea, juice, sports drinks etc) and foods which often contain high amounts of water (i.e., watermelon or cucumbers).
Diet drinks and Caffeine
The kidneys have the job of filtering unwanted chemicals from your body. Drinking too many diet drinks each day will force your kidneys to excrete unwanted chemicals or artificial sweeteners. As a result of the body cleansing process, additional water must also be excreted in the process making it more challenging for a person to keep their body well hydrated. Thus, to reduce the kidney’s need to work over-time filtering, consume drinks that do not contain artificial sweeteners, dyes, and other chemicals!
You commonly hear advice to avoid caffeinated drinks because they are diuretic in nature. Downing only caffeinated drinks all day long is clearly not a good health strategy, but one or two caffeinated beverages in the morning or early afternoon will likely not have any major effect on your hydration status. In sedentary individuals, drinking too much caffeine can have a diuretic effect for 2-3 hrs post consuming the drink. However, if someone takes a caffeinated beverage (A single cup of coffee) right before exercise, the literature shows that it can actually improve endurance by helping burn fat better during exercise without significantly reducing hydration status.
Game Plan: Keys To Good Hydration
For most people, hydration guidelines are not very complicated. Start you day with a glass of water. 20-30 minutes before each meal consume another glass of water. In fact, research shows that people who drink 6-8 ounces of water just prior to a meal tend consume less calories, thus, helping you to maintain your body weight by not over-eating.
If you are exercising to lose weight and get fit, when you exercise more than an hour, instead of drinking a full strength energy/electrolyte Gatorade like drink, dilute the drink in half to two-thirds. This strategy helps to provide the needed water you’re losing during exercise while not over-feeding your body with liquid calories. Depending on your health status (i.e., normal blood pressure versus some level of hypertension), carefully monitor your caffeinated beverage intake so you get the positive benefits of these drinks (i.e., increased mental alertness or positive effects on exercise endurance) while minimizing the negative effects of excessive caffeine intake (i.e., increased blood pressure responses).
There is a huge debate across scientists about using our natural thirst sense to re-hydrate ourselves. For example, I began to get thirsty about 20 minutes ago, but have not yet taken a drink. Because I am in a sedentary state sitting at my computer, I am getting a little under-hydrated; yet this short delay is not detrimental to my over-all hydration status or harmful to my health. However, were I to ignore my thirst while exerting a hard treadmill workout, or running outside in summer heat would not only severely dehydrate my body, but also put my life in a very dangerous situation.
In fact, during exercise never wait until you are thirsty to drink water, or water/electrolyte solutions. Start your exercise with 4-6 ounces of fluid. Recommendations are:
- Water for workouts lasting under an hour
- Gatorade-like drink for workouts lasting longer than 90 minutes continuously at a moderately high intensity pace
- Then, continue to take an additional 4-6 ounces of your desired fluid beverage every 20-30 minutes
Nutrition and For the Long Term
Diet wise, if you are big-time meat and potato eater while seldom eating vegetables or fruits on daily basis, it is very important that you include some form of low-sodium fluid with your meals, i.e., water, decaffeinated green tea, or diluted natural fruit juices. This helps to offset the low fluid and higher salt content of a carnivore type diet.
If you are trying to lose weight, following the water drinking strategies discussed above with one additional guideline: When you feel the desire to drink a calorie containing beverage like a natural fruit juice or say sweet tea, absolutely try to always dilute that beverage. The larger the drink you get for yourself, the more diluted you need to make that drink. For example, a 32-ounce Coke bought at a fast-food restaurant contains approximately 400 kcal total. In order to burn off that many calories through exercise it would take 90 minutes of walking on a treadmill at 0% grade equal to 4-5 miles just to break even on the extra calories!
Additionally, (body) water content varies greatly with age. For example, water content in a healthy, normal weight, new born infant is approximately 73% of the infant’s total body weight. When that same infant becomes a senior citizen moving into their 60s and 70s, the body’s total water content can be much lower. Interestingly, how much water a person’s body contains has a lot to do with how active they stay.
Active adults that hydrate well, eat a well-balanced diet usually are not only leaner, but also are better able to maintain lean muscle mass. In other words, an active physically fit person has a stronger healthier body.
Why is this important to our body’s hydration status? Maintaining our lean body mass is important because our body’s muscles are 75% water while are body fat water content is around 10% only. Thus, staying active is not only good for our general well-being and health, it is good for us because it helps us maintain well-hydrated muscle and organ tissues throughout our entire body.
Stay hydrated, and see you in the studio!