Low Water Intake Worsens Focus, Mood & Energy

Posted by

The Institute Of Medicine (IOM) suggests that male’s consume around 3.7 L of fluid daily and women consume 2.7 L of fluid daily.

Fluid, of course, can be ingested in various forms including water (the most likely candidate) as well as tea, coffee, other beverages as well as modest contributions from the foods we consume regularly – particularly fruits and vegetables.

As you might imagine, these recommendations could vary greatly based on individual factors but at the very least provide a useful reference point.

Which leads me to the the subject of today’s article, the relationship between water intake and various daily mental functioning considerations like mood, focus and energy levels.

Let’s dive right in (pun intended).

Water & Mental Functioning – Insights

“When dehydration reduces body mass by more than 2%, it has been consistently reported that mood is influenced, fatigue is greater, and alertness is lower.”

Nutrition Reviews 2015


“High-order cognitive processing (involving attention and executive function) and motor coordination appear more susceptible to impairment following dehydration”

Medicine And Science In Sports And Exercise 2018


“Accumulating evidence supports the notion that hydration state affects cognitive ability and mood. Severe dehydration has been shown to cause cognitive deficits such as short-term memory and visual perceptual abilities as well as mood disturbance, whereas water consumption can improve cognitive performance, particularly visual attention and mood.”

British Journal Of Nutrition 2014


There is also methodologically  limited but intriguing evidence to suggest that, when compared to those who drink the least water, individuals with higher intakes have lower mortality and depression risks.

But let’s dig deeper into some insightful experimental studies.

Study #1 – PLoS One 2014

In this very fascinating experimental study researchers took a group of people who usually drank not much water ( <1 L) and a group of people who consumed closer to adequate levels (2-4L) and essentially swapped their intake levels for three days.

They found that when low water consumers drank more, they felt more alert, more awake and less sleepy.

They also found that when high water consumers drank less, they felt more tired, less calm and overall experienced more negative emotions.

Study #2 – Int J Environ Res Public Health. 2020

In this study, once again a fascinating one, researchers found that young adults who consumed 500 ml vs 200 ml vs 0-100 ml of water upon waking exhibited differences in their fatigue, mood and working memory with the greatest overall benefits experienced at 500 ml, some benefit experienced at 200 ml, and the overall worst outcomes experienced in those consuming 100ml or less.

Although research in this area can be challenging for a host of reasons, not least of which is all of the potential confounding variables, there is clear evidence to suggest that water intake likely has a meaningful role to play in enhancing mental functionality, mood and general emotions.

The benefit, as we might expect, is probably most notable in those who are either low water consumers at baseline or find themselves dehydrated (which can happen for a variety of reasons) and not probably addressing their water loss.

Drink up!

Andy De Santis RD MPH