Hydration & Thirst

By: Melissa Chavez, RD LDN

The official first day of summer this year is Wednesday, June 21, but in many places it already feels like summer. With temperatures rising your hydration needs rise as well, especially when exercising outdoors. This makes it extra important to drink water. Water makes up approximately 60% of our bodies and helps us keep a normal body temperature. Fluid needs vary from person to person but the National Academy of Medicine recommends 13 cups for men and 9 cups for women. This can be from water and/or other beverages. Also, note fluid needs are higher with hot climates, physical activity, and when one is sick.

You may think you have your thirst to help ensure your fluid needs are met. However, thirst is often not perceived until a person has lost about 1-2% of body mass. In the study, “The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration”, it was found that that relying solely on thirst as a means of staying hydrated during exercise, especially in the heat, may not be enough and may lead to dehydration. The study provided a bolus of fluid to individuals after approximately a 3% body mass loss had occurred following exercise and recovery time in the heat. It was found that the perception of thirst quickly declined to levels seen in euhydrated individuals for up to 60 minutes following exercise. Interestingly, this was despite a level of dehydration exceeding 2% body mass loss. The study concluded the decreased thirst perception with less fluid consumed than lost may prevent one’s ability to rehydrate rapidly following prolonged exercise. The study went on to state these findings support the recommendation of individuals knowing their individual fluid needs and that recommendations should be based on individual fluid losses.

If we cannot rely solely on thirst what else can we do to assess our hydration levels? Monitoring your urine can be helpful. Transparent urine may indicate over-hydration and that you can cut back on the water some.. Light yellow, lemonade-like to light beer color indicates good hydration. However, darker than that starts to show dehydration. Amber indicates mild dehydration. Colors ranging from brown to dark orange can show severe dehydration. Note, there are also some medical conditions, foods, and medications that can affect color. It can still be helpful to know your baseline.

Tips to maintain hydration:

• Keep a reusable water bottle with you

• Limit alcohol intake

• Drink a lot of water before you work out

• Eat fruits and vegetables such as watermelon, strawberries, tomatoes, cucumbers, and lettuce

Maintaining hydration involves knowing your body and not only relying on thirst as an indicator.

References

Adams, W. M., Vandermark, L. W., Belval, L. N., & Casa, D. J. (2019). The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration. Nutrients, 11(11), 2689. https://doi.org/10.3390/nu11112689

Shoemaker, S. (2023, February 10). 12 simple ways to drink more water. Healthline. https://www.healthline.com/nutrition/how-to-drink-more-water

Colgrove, K. (2022, July 15). Tips for staying hydrated during the Summer. UNL Food. https://food.unl.edu/article/tips-staying-hydrated-during-summer