Hydration is the most over-promised and under-explained habit in fitness. "Drink more water and watch the fat melt" is nonsense — water doesn't burn fat. But staying properly hydrated genuinely makes losing fat easier, and most people walk around mildly dehydrated without knowing it. Here's the honest version.

Water doesn't burn fat — but it removes obstacles

You won't lose a kilo of fat by drinking an extra glass. What hydration does is clear the obstacles between you and your result:

  • It blunts appetite. Thirst is frequently misread as hunger. A glass of water before a meal genuinely reduces how much you eat — this one is backed by controlled studies, not bro-science.
  • It improves training. Even 2% dehydration measurably drops strength, endurance, and focus. A dehydrated session is a worse session, and worse sessions add up.
  • It supports everything mechanical. Digestion, joint comfort, temperature regulation, energy — all run better hydrated.

Forget the flat "2 litres"

The famous "eight glasses a day" has no real scientific basis — it's a number that stuck. Your actual needs depend on your size, how much you move, and your climate. A 95 kg man training in summer needs far more than a 55 kg woman at a desk in winter.

A practical, evidence-aligned target is 30–40 ml per kilogram of body weight per day. For an 80 kg person that's roughly 2.4–3.2 litres — and more on heavy training days or hot Amsterdam summers. Our water intake calculator does this maths for you in seconds.

You don't drink it all — you eat some of it

Around 20% of your fluid comes from food, especially fruit, vegetables, soups, and yoghurt. So you don't need to chug the full litre figure in plain water. Coffee and tea count too — the old "caffeine dehydrates you" claim is overstated for habitual drinkers; the fluid in a coffee far outweighs its mild diuretic effect.

Don't forget electrolytes — especially when dieting

Water alone isn't the whole hydration story. Electrolytes — sodium, potassium, and magnesium — are what allow your body to actually use the water you drink and keep fluid balanced inside and outside your cells. This matters more than usual when you're losing fat, because a lower-calorie, whole-food diet often comes with less sodium, and you flush more out as you drop water weight.

The symptoms people blame on "low carbs" or "the diet" — headaches, fatigue, light-headedness, cramps, brain fog — are frequently just low electrolytes. A pinch of salt in your water, salting your food normally, and eating potassium-rich foods (potatoes, bananas, leafy greens) usually fixes it. Drinking gallons of plain water while cutting salt can paradoxically make you feel worse, not better.

Can you drink too much? Yes

More is not infinitely better. Drinking extreme volumes in a short window — litres in an hour — can dilute blood sodium to dangerous levels (a rare condition called hyponatraemia). You won't get there with sensible daily sipping, but it's a reason to ignore "force down 5 litres" advice. Spread your intake across the day rather than front-loading or panic-chugging.

The simple system that actually works

Don't track every glass. Build triggers instead:

  1. A large glass on waking, before coffee.
  2. A bottle on your desk you refill on a schedule.
  3. A glass before each meal (this is where the appetite benefit lives).
  4. Extra around training.

The honest check is your urine: pale straw means you're fine; dark yellow means drink more. It's that simple.

Hydration won't transform your body on its own — but combined with the right calories, enough protein, and progressive training, it's one of the easiest wins available. Work out your daily target →