How mild dehydration hides
You don't need to feel parched to be under-hydrated. A fluid loss of as little as 1-2% of body weight can measurably affect concentration and mood before thirst even kicks in properly. Thirst is a lagging signal, not an early warning system.
What actually counts
Tea, coffee and food all contribute to daily fluid intake - the old idea that caffeinated drinks don't count has largely been walked back. That said, plain water remains the most efficient way to hit your targets without added sugar or excess caffeine.
A simpler target than eight glasses
The 'eight glasses a day' rule is a reasonable starting point but ignores body size, activity level and climate. A more useful check: your urine should be pale yellow, not clear (a sign of overhydration) and not dark (a sign you're behind).
- Start the day with a full glass before coffee
- Keep a bottle somewhere visible - visibility drives intake more than willpower
- Add electrolytes on high-sweat days, not just hot ones
- Treat a headache or afternoon slump as a hydration check before anything else
Where a multivitamin fits in
A multivitamin can fill genuine gaps, particularly for restrictive diets, but it can't substitute for basics like hydration and sleep - it works quietly in the background while dehydration works loudly and immediately. Fix the fundamentals first; layer supplements on top of a foundation that's already solid, not instead of one.
