13 Hydration FAQs, Answered by an Expert

Summer is here and for many people, that means spending more time outside in the sun. Whether you’re hitting the trail, hanging at a backyard gathering, or soaking up the sun at the beach, one of the most important things to remember—in the summer and all seasons—is to stay hydrated.

The internet is filled with a myriad of different hydration “hacks” and tricks, making it tough to find the best ones with the most science behind them. To help set the record straight, we asked an expert some of the most frequently asked questions about hydration. Marisa Sweeney is an MS-RDN (Registered Dietitian Nutritionist), the former President of the NJ Academy of Nutrition and Dietetics, founder of the NJVeg Fest, and owner of BeWell Integrative Health Services. Consider this hydration 101. 

Is it really necessary to consume 8 full glasses of water per day?

Marisa Sweeney, MS-RDN: Just like nutritional needs are unique to each individual, hydration needs are too. Many variables influence how much water someone needs daily that can change every day depending on the level of physical activity, perspiration, medical conditions, etc. [Considering that] one pint is 16 fluid ounces, 8 of those [would equal approximately] 128 ounces. For perspective, that would amount to a full gallon of water per day!

Is there a more reliable way to determine our personal hydration needs?

MS: According to some of the more research and evidence-based equations for determining hydration needs, this may exceed what the majority of people need. A great empirically supported equation to use to determine hydration needs is 1mL for every calorie you eat. Granted, I do not believe it is necessary to count every calorie you eat every day to precisely determine that amount of water needed, but it is a good general equation.

For example, if you eat about 1500 calories a day on average, then [you would] drink about 1.5L (~50 ounces) of water as a baseline minimum. If it is more like 2000 calories on the average, have 2L (~68 ounces) of water as a baseline minimum. Of course, if you are still thirsty after reaching these water intake goals, then drink more.

What’s a reliable way of determining your hydration status?

MS: Assessing the color of your urine is a good indicator of hydration status. If it is a dark yellow color, this is an indication of being dehydrated and could mean you need to drink more water. A light yellow color is generally what you want.

If you have any kind of medical condition that influences water needs, it is recommended to consult with your doctor or a registered dietitian to determine the appropriate amount of daily water intake for you before relying on any generalized equations.

Does the temperature of your drinking water matter?

MS: Staying adequately hydrated regardless of the temperature of the water is most important above anything else. This being said, the temperature of your water has mild biochemical effects to consider. Drinking cooler/cold water in hot conditions, especially when sweating, is helpful to keep your body temperature within a desirable range.

Some research has shown that drinking room temperature or warmer water at particular times has its benefits as well. This includes drinking warm water to improve sleep cycles, get a metabolic boost in the morning, and even improve gastrointestinal symptoms.

Do coffee and tea work against hydration, or can they count towards overall individual fluid intake goals?

MS: There is only a mild diuretic effect that happens when you drink coffee or tea, especially when it is caffeinated. Since there is not a net loss of hydration when drinking coffee or tea, as a general rule, you can count coffee and tea towards your fluid intake for the day. However, nothing hydrates better than water!

Do sports drinks or coconut water hydrate you better than water?

MS: Sports drinks and electrolyte supplements do not “hydrate better” than water does. However, having electrolytes added to your water or drinking coconut water that naturally has an electrolyte content, can be beneficial when you are sweating to maintain an electrolyte balance.

Every time you perspire, you sweat out sodium, potassium, and other electrolytes that can cause imbalances, especially if you are sweating excessively. These imbalances can make people feel dizzy or run down, and if severe enough, can cause medical emergencies. This is where electrolyte replacement supplements and drinks can be beneficial, but [they don’t] hydrate better than water.

Are there any fruits or vegetables that can help keep you hydrated?

MS: You can most certainly boost hydration by consuming fruit and vegetables that naturally have higher water content. Some examples of this are cucumbers, watermelon, oranges, peaches, bell peppers, broccoli, and celery.

Are there any beverages or foods that can negatively impact your body’s ability to hydrate?

MS: Salty and sugary foods, alcohol, and diuretic foods/drinks [like lemons, ginger, garlic, and bananas] can cause a loss of hydration. High-protein foods require increased water intake for digestion.

Can drinking water infused with lemon, cayenne, cucumber, etc. help boost energy and metabolism?

MS: No studies show a direct link between drinking lemon or cucumber water and losing weight or boosting metabolism. However, limited research reports that eating fresh chili pepper can raise metabolic rates for up to 30 minutes after consuming it, and promotes increased feelings of fullness and fewer cravings.

Is there any truth to the claim that when you feel hungry, you may actually just be thirsty?

MS: There is a shared part of your brain responsible for interpreting hunger and thirst, so these sensations can often get confused. A simple but great strategy to differentiate hunger from thirst is to make sure you are well hydrated before deciding to eat. For example, before you go for a snack drink a full 8 ounces of water first and then wait 10 minutes, if you are still hungry at that point, then have a snack. Otherwise, you likely might have just been thirsty and misinterpreted the feeling.

Does the pace of hydration matter? Can you drink a full glass of water every few hours, or is sipping as needed better?

MS: Many medical organizations recommend drinking a full glass of water about 30 minutes before eating a meal as it can aid in digestion. Sipping on water throughout the day to increase/maintain your hydration status is optimal, rather than going extended periods without hydration.

Is it necessary to drink a full glass of water every morning to start your day, and again at night before bed?

MS: It is most certainly beneficial to start and end your day drinking water. We lose fluid while we sleep. Even just breathing while we sleep causes us to lose hydration. However, there is a balance to consider with drinking water before going to bed. You do not want to drink so much water that your sleep is interrupted by having to go to the bathroom frequently. Try drinking 8 ounces of water before going to bed and another 8+ ounces when you wake up, and assess if it is interrupting your sleep cycles before you drink more.

While we are on the topic of sleep, is there any connection between hydration and sleep quality?

MS: The Sleep Foundation reported on evidence that a lack of sleep may contribute to dehydration. In a study of nearly 20,000 adults in both the United States and China, people who slept only six hours per night were found to have significantly higher rates of dehydration than people who slept eight hours. It is important to note that association doesn’t always mean causation, but research shows a link between sleep and hydration.

This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment and before changing your diet or healthcare regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.