Most people know alcohol is dehydrating. Fewer people understand why — or what specifically is being lost alongside the water. The answer matters a lot for how you feel the next day.
Why Alcohol Causes Dehydration
Alcohol suppresses antidiuretic hormone (ADH), also called vasopressin. ADH's normal job is to signal the kidneys to retain water. When ADH is suppressed, the kidneys stop reabsorbing water and begin excreting it — along with the electrolytes dissolved in it.
For every gram of alcohol consumed, the kidneys excrete approximately 10ml of additional urine beyond normal baseline. Over a night of drinking, this adds up to significant fluid loss — and with it, significant electrolyte loss.
What's Actually Being Lost
Sodium. The primary electrolyte in extracellular fluid, sodium governs fluid balance throughout the body. Sodium depletion contributes to headache, nausea, and the general feeling of physical depletion.
Potassium. Critical for muscle function, nerve signalling, and maintaining cellular fluid balance. Low potassium (hypokalemia) causes muscle weakness, cramping, and fatigue.
Magnesium. Involved in over 300 enzymatic reactions in the body, including ATP synthesis (energy production), protein synthesis, and nervous system function. Magnesium is also important for sleep quality — its depletion contributes to the poor, unrestorative sleep common after drinking.
Why Standard Hydration Isn't Enough
Drinking water helps, but water alone doesn't replace electrolytes. In fact, drinking large amounts of plain water after significant electrolyte loss can further dilute the electrolyte concentration in your blood — potentially worsening symptoms.
Effective rehydration requires replacing the electrolytes alongside the fluid. Sports drinks do this to an extent, but most are formulated for sweat-based loss during exercise — high in sodium, lower in potassium and magnesium. The electrolyte profile of alcohol-induced loss is different.
The Reeva Approach
Reeva includes potassium (as tripotassium citrate) and magnesium (as magnesium gluconate) — both in forms with good bioavailability — alongside sodium from the formula's base. The goal is to pre-load electrolyte reserves before the diuretic effect of alcohol begins, rather than trying to replace them after the fact when absorption may be compromised.
Electrolyte management is one of the less glamorous aspects of the Reeva formula. It's also one of the most important.