Electrolytes are more popular than ever, and for good reason!
Most of us have heard the same advice: you need to drink more water. But if you’ve ever made a conscious effort to increase your intake and still felt tired, foggy or surprisingly thirsty, there’s a physiological explanation.
Hydration isn’t just about how much water you consume; it’s about how effectively your body can move, absorb and retain that water at a cellular level.
This process depends on electrolytes. Specifically: sodium, potassium and magnesium — minerals that determine where water travels in the body, how long it stays and whether your cells can utilise it efficiently.
When these minerals fall out of balance, your hydration does too. And this can happen long before you begin to feel thirsty.
The Science: Hydration Begins Inside the Cell
Around 60% of the human body is water, split between two biological compartments:
- Intracellular Fluid (ICF): Water inside your cells
- Extracellular Fluid (ECF): Water outside your cells, including plasma
Cell membranes regulate water movement between these compartments through osmosis, which is controlled by electrolytes. This balancing act is essential for:
- Energy production
- Cognitive performance
- Muscle function and relaxation
- Temperature regulation
- Circulation and nutrient transport
When electrolytes drop (whether from sweat, stress, caffeine, alcohol, heat or low-mineral diets) water distribution becomes inefficient. Cells can’t hydrate properly, even if you’re drinking plenty of water.
Early signs of this cellular dehydration include:
- Fatigue
- Reduced concentration
- Headaches
- Muscle tightness
- Brain fog
- Skin looking flat or dull
These symptoms appear before traditional dehydration signs, because the imbalance begins at the cellular level.
What Electrolytes Actually Do
Electrolytes maintain electrical gradients that allow water, glucose and other nutrients to move across membranes. Without these gradients, your overall hydration can be impaired.
Sodium: The Primary Fluid Regulator
Sodium (arguably the most well-known electrolyte) regulates fluid in the extracellular space and supports blood volume, as well as enhances fluid retention (Del Coso et al., 2016).
Insufficient sodium can reduce water absorption efficiency and increase urinary losses. In extreme cases, excessive water consumption without sodium replacement can dilute blood sodium levels (Von Duvillard et al., 2004).
Potassium: The Intracellular Hydrator
Potassium regulates water inside cells, powers the sodium–potassium pump and supports nerve conduction. It can also supports muscle contraction and relaxation (Maughan et al., 1997).
Potassium losses through sweat must be replaced to maintain intracellular hydration.
Magnesium: The Cellular Facilitator
Magneisum is involved in over 300 enzymatic reactions in the body (Al Alawi et al., 2018). It supports ATP (energy) production and helps maintain ion channel stability.
Magnesium also indirectly supports the movement of water into cells and fluid equilibrium. Low magnesium compromises cellular function and can contribute to poor hydration efficiency.
Together, these electrolytes determine whether the water you drink is effectively used by your cells, or rapidly excreted.
Why Water Alone Isn’t Enough
Water hydrates the body only when the correct minerals are available to regulate its movement. Without electrolytes:
- Water absorption becomes less efficient
- Urination increases
- Blood sodium can become diluted
- Cells struggle to retain water
- Fatigue and cognitive decline appear despite high intake
This is why many people drink large volumes of water yet still feel dehydrated.
Electrolytes make hydration effective by enabling water to move where it needs to go and stay there.
Understanding Dehydration (Before You Feel Thirsty)
Dehydration can happen very quickly. Research shows that just a 1–2% reduction in body water (roughly 1 to 1.5 litres) can impair:
- Cognitive function
- Reaction time
- Mood and irritability
- Thermoregulation
- Blood pressure stability
- Physical performance
The thirst mechanism typically activates only once this threshold is reached, meaning dehydration begins well before you feel thirsty.
It's important to note that an individual's hydration needs will increase with everyday factors such as:
- Heat and climate
- Caffeine consumption
- Alcohol
- Stress hormones
- Air conditioning
- General movement and sweat
- Travel
- Fasting or low-carb eating patterns
Water & Electrolytes vs Water Alone
Research consistently shows improved hydration when water is paired with electrolytes. Enjoy the below for further reading:
1. Sodium Improves Fluid Retention
Sodium supports plasma volume and helps maintain hydration more effectively than water alone (Del Coso et al., 2016).
2. Magnesium Supports Cellular Balance
Magnesium helps regulate ion channels and supports efficient water movement into cells (Al Alawi et al., 2018).
3. Potassium Restores Intracellular Hydration
Potassium is essential for re-establishing cellular fluid balance after losses (Maughan et al., 1997).
4. Electrolytes Reduce Risk of Dilutional Dehydration
Water alone can lower blood sodium; electrolytes maintain safe osmotic balance (Von Duvillard et al., 2004).
Electrolytes aren’t optional. In our modern, busy lives, they are physiologically required for effective hydration!
References:
Del Coso J et al. Effects of oral salt supplementation on physical performance. Scand J Med Sci Sports. 2016;26(2):156-164.
Al Alawi AM et al. Magnesium and Human Health. Int J Endocrinol. 2018;2018:9041694.
Maughan RJ et al. Recovery from prolonged exercise: restoration of water and electrolyte balance. J Sports Sci. 1997;15(3):297-305.
Von Duvillard SP et al. Fluids and hydration in prolonged endurance performance. Nutrition. 2004;20(7-8):651-656.