Author: Maria Fischer • Fact checked by: Tara D. Thies • March 25, 2021
Ultimate Guide on the Best Ways to Rehydrate
Hydration is at the core of a proper fitness and nutrition regimen. The human body is made up of approximately 60 percent water, so it’s no shock that hydration is crucial for essential functions — including ones that impact fitness level and athletic performance.
When the body is hydrated, it is in a state called euhydration. According to the National Athletic Trainers' Association position statement, euhydration is the state of optimal total body water content as regulated by the brain. In an euhydrated state, intracellular and extracellular fluid volumes are maintained with minimal physiological adjustment, and the body's systems function most efficiently.
On the other end of the spectrum is dehydration, which is defined by the National Athletic Trainers’ Association as the process of losing body water. Dehydration is influenced by exercise intensity, environmental conditions such as temperature and humidity and availability of fluids during exercise. When the body is dehydrated, it is unable to carry out its normal functions. It’s imperative that you rehydrate before you slip into a state of dehydration, but how do you even know when you’re in a state of dehydration? Then once you’ve recognized you’re dehydrated, what’s the best way to rehydrate and return to a state of euhydration?
Below, we’ll explore hydration basics and give you tips and tricks for rehydration.
Hydration basics: How to tell if you’re properly hydrated
The key to rehydrating is knowing when you’re hydrated and when you’re (likely) dehydrated.
Most medical professionals divide dehydration into three different stages: mild dehydration, moderate dehydration and severe dehydration. Mild dehydration can often be reversed without seeking medical treatment — you just need to rehydrate by intaking fluids that contain electrolytes lost during activity.
(Moderate to severe dehydration, however, requires medical attention.)
So how can you tell if you’re on the verge of mild dehydration? It’s important to note that there is no one method considered “the best” in terms of assessing an individual’s hydration status; in fact, many methods can be invasive in nature and aren’t recommended for daily use.
However, there are a few methods that can be used to measure hydration level:
Urine color: According to a 2016 study titled published in the European Journal of Nutrition, analyzing urine color is a practical way for individuals to evaluate and adjust hydration behaviors. The general rule of thumb is the darker the urine color, the greater degree of dehydration.
Sensation of thirst: Assessing one’s sensation of thirst can also be a good indicator of dehydration. Like analyzing urine color, it’s a practical way for individuals to evaluate their hydration — no invasive measures involved. Thirst develops once dehydration has already set in, roughly 1-2% of body mass loss.
Urine Specific Gravity (USG) measurement: USG is a measurement of urine concentration as compared to pure water. A USG test is done by a healthcare provider and can help determine how well your kidneys are diluting your urine. According to the Korey Stringer Institute at the University of Connecticut, USG of less than 1.020 indicates euhydration. A 2018 study published in the peer-reviewed journal BMJ Open Sports & Exercise Medicine notes that a USG of more than 1.020 is defined as dehydration.
Blood measures: Measuring plasma osmolality, plasma volume, hematocrit concentrations and hemoglobin can determine a person’s level of hydration and dehydration; however, this is one of the methods considered invasive and it is not recommend this method for individuals who are simply curious about their hydration level on a day-to-day basis.
Of the options above, assessing urine color and sensation of thirst are the two easiest ways to determine whether you’re hydrated or dehydrated.
You can also look out for additional symptoms of dehydration, which may include:
Very dry skin or dry mouth
Feeling dizzy or fainting
Rapid heartbeat or breathing
Lack of energy
Confusion or irritability
Hydration maintenance and minimizing dehydration
After assessing urine color, sensation of thirst and other symptoms of dehydration, you’ve determined that you need to rehydrate — so what next?
You can rehydrate your body by consuming fluids that contain the electrolytes lost during activity. Electrolytes are minerals that are vital for many body functions. These minerals regulate the fluid levels in your blood plasma and your body, balance your pH levels (the measure of acidity and alkalinity), help enable muscle contractions, transmit nerve signals, help blood to clot and help the body build new tissue.
Despite their numerous roles in the body, these minerals are often linked with hydration. Sweat contains electrolytes — particularly, a significant amount of sodium and small amounts of potassium, calcium and magnesium. When you sweat from working out or other forms of activity, your body loses these electrolytes. On average, you lose around 1 gram of sodium with every liter of sweat.
To ensure your body avoids dehydration and stays in a state of euhydration, you need to replenish the electrolytes lost through sweat. But how do you determine how much fluid to drink to rehydrate? The most popularized recommendation is to drink eight glasses of water per day. At roughly eight ounces per glass, this rule is sometimes called the “8x8” rule for hydration. While it’s a good place to start, the actual amount of water you need varies based on your habits, as well as your biology and climate. For men and women who engage in athletic activity, have certain medical conditions or live in hot climates, eight glasses per day might not be enough water and more fluids may be needed to hydrate.
If you’re someone looking for post-workout rehydration tips in particular, try calculating your sweat rate. You can use the following equation to find your sweat rate: (pre-exercise bodyweight – post exercise bodyweight) + fluid intake – urine volume divided by exercise time in hours. This calculation can tell you how much fluid you typically lose during activity.
Another method for calculating sweat rate involves weighing yourself, then exercising for a full hour without drinking water or any fluids. You should begin by hydrating before starting a one-hour workout. You’ll want to check your urine for a light color, as starting a workout dehydrated will affect normal sweat rate. Weigh yourself and document your body weight before the workout. Exercise for one hour, making sure the type and intensity of exercise mirrors the conditions in which you normally workout. Do not drink water or any fluids during the one-hour workout. If water is consumed, weigh the water before and after the workout to determine the difference so you can get an accurate sweat rate. After the workout, weigh yourself again and calculate the body weight difference between pre- and post-exercise. Again, if water is consumed during exercise, subtract the water weight from the post-exercise weight. For every pound lost, a person should replace it with 2 cups of fluid.
That said, rehydration and proper water intake isn’t only important around the time of your workout. You should aim to stay hydrated throughout the day, regardless of when (or how often) you work out. To easily maintain proper hydration throughout the day, it helps to keep water with you at all times. You can also make sure your diet is filled with hydrating fruits and veggies, such as watermelon and cucumber. (Fun fact: watermelon is made of 92% water — hence, the name watermelon.)
For more tips and tricks, visit Gainful’s guide to staying hydrated — and hydrating fast.
Best drinks to rehydrate your body
There are a number of fluids you can consume to rehydrate your body: Water, sports drinks, coconut water, fresh fruit juice, Pedialyte — the list is seemingly endless.
Which is the best for rehydration? Fluid-energy-electrolyte replacement beverages — aka sports drinks, such as Gatorade — have electrolytes, while water does not. Sports drinks also have carbohydrates, which improve the rate of intestinal uptake of sodium, which in turn favors the retention of water. The added electrolytes and carbohydrates makes sports drinks a popular drink choice after an intense workout.
There’s a catch, however: Although sports drinks’ carbohydrates and electrolytes can help during exercise sessions lasting sixty minutes or more, most experts agree that plain water is the best fluid to drink when activity or exercise sessions are less than one hour. According to researchers, there is no added benefit of drinking sports drinks over water during exercise sessions that are low intensity, in a moderate climate or less than sixty minutes. When workouts are shorter, the body does not lose the amount of electrolytes that a sports drink would help mitigate, nor does it need the added sugar that is found in sports drinks.
Coconut waters and fruit juices also serve their purposes for rehydration. Coconut water and fruit juice contain about 95 percent and 85 percent water respectively, which makes these fluids especially hydrating. They also contain vitamins within the natural fruits they’re made from. While they often contain less sugar than most sports drinks, they still do have a higher sugar content compared to water.
Pedialyte is also popular for rehydration, especially among those who have more moderate levels of dehydration. Pedialyte has a special level of sodium that can restore fluid levels more effectively than soda, juices or sports drinks. These other drinks are much too low in sodium and way too high in sugar content. Severe dehydration requires a different level of sodium, which Pedialyte is designed for based on World Health Organization (WHO) guidelines. Because Pedialyte also contains electrolytes, it is often considered more effective than water for treating dehydration. The precise combination of electrolytes and sugars in Pedialyte helps to restore fluid levels and nutrients that are lost through excessive sweating, urination, vomiting or diarrhea.
Confused on which drink is best for you and your rehydration needs? Consider looking into a personalized hydration formula.
Rehydrate with a personalized hydration formula
For those seeking an effective amount of electrolytes based on workout frequency, intensity and sweat levels, Gainful offers a high-performance formula of four electrolytes and cane sugar that’s made just for your body. Gainful’s hydration formula is able to hydrate faster than water alone. The formula comes in two refreshing flavors, Lemon-Lime or Strawberry Lemonade, and it’s shipped to you in 21 convenient single-serve packs. All you have to do is just add to 8-16 oz of water and shake it all together in a water bottle.
If you need an extra boost of energy, there’s also a caffeinated option that contains 150mg of caffeine and 250mg of L-Theanine for a jitter-free energy boost. All of Gainful’s hydration packs are non-GMO and 100% plant-based, with no artificial flavors, colors or sweeteners.
For athletes, a personalized hydration drink will help minimize fluid loss to less than 2% total, which is the threshold for performance decline. Take Gainful’s quiz to find your own personalized hydration formula. (You’ll also find your perfect protein powder blend in the process.)
Bonus for subscribers: You also have access to the experts at Gainful. Every Gainful subscription includes unlimited access to a Registered Dietitian, who can answer any questions you may have about hydration.
Gainful understands proper hydration is an important aspect of any health and wellness plan. No matter where you’re at on your wellness journey, we’re here to help you prioritize hydration — and rehydration — and provide all the information you need to reach your fitness goals.
Gainful is your rehydration solution.
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