Hydration: How to Assess Your Hydration Status

Despite several water intake recommendations, a better way to monitor hydration levels may be through markers such as urine color (1).

Although dilution methods to determine total body water via plasma osmolality measurement are the most accurate, valid, and sensitive ways, they are not practical for most situations (2,3), but total body mass and urine color when used in conjunction is a good way to assess hydration status (2,3).

Significant changes in urine color occur within 24 h of modifying fluid intake volume (16) suggesting that individuals can use urine color monitoring as a simple way of evaluating the adequacy of their fluid intake (17).

First-morning urine should look like pale yellow (1), indicating the normal and expected presence of some waste products from metabolism overnight. This color corresponds to a state of euhydration (4,5) (it shouldn´t look like water, or anything dark), 5 clear urinations per day with two after training is a good rule of thumb.

Thirst is initially perceived when a body weight deficit of 1–2 % exists (6,7), fluid consumption should be adequate to avert the perception of thirst. Thirst signals any imbalances of the osmolality of fluids and tissues (the electrolyte concentration), and the total amount of water in our body (volume).


Dehydration is characterized by weight loss, confusion, dry skin that is hot to the touch, and possibly an elevated core body temperature. In a hot climate, dehydration can be dangerous and result in thermal injury. Other causes of dehydration can be excess diarrhea, vomiting due to GI dysfunction, kidney disease, and diuretic medications

Thirst may be a poor measure of hydration because of the lag between the physiological dehydration and the thirst signal. Special populations require more attention, elderly are less sensitive to the thirst mechanism due to the deterioration of osmoreceptor sensitivity (2,8-12); and children are inexperienced in interpreting the thirst response (13,14). 

Older adults are also at higher risk for reduced kidney filtration function, which results in less efficient water conservation (when dehydrated), further exacerbating difficulties in recognizing a dehydrated state (15).

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17. Erica T. Perrier Evan C. Johnson, Amy L. McKenzie, Lindsay A. Ellis, and Lawrence E. Armstrong. Urine colour change as an indicator of change in daily water intake: a quantitative analysis. Eur J Nutr. 2016; 55: 1943–1949.