Water Before Meals Calculator
Drinking water before meals can blunt appetite — see how much a pre-meal glass adds up to across your day.
How it works
Pre-meal water = meals × ml per meal · Cups = total ÷ 240 · Share = total ÷ daily goal × 100
In controlled trials, drinking roughly 500 ml of water about 30 minutes before meals led dieters to eat less and lose modestly more weight, likely through stomach distension and a brief dip in hunger signals. The effect is small and works best alongside a calorie-controlled diet, not on its own. This tool tallies the daily volume so you can fold it into your overall fluid target rather than double-counting.
Worked example
A 500 ml glass before each of 3 meals is 1,500 ml — about 6.3 cups, or 60% of a 2,500 ml daily fluid goal. The rest can come from other drinks and food.
Frequently asked questions
How long before a meal should I drink?
The satiety studies used about 30 minutes ahead. Drinking a large volume during the meal itself can feel bloating for some people and may not curb intake as reliably.
Is 500 ml the right amount?
That was the tested dose in adults, but scale to comfort. A smaller glass still hydrates; the appetite effect is strongest with a genuinely filling volume.
Can I drink too much water?
Very rarely, but overdrinking in a short span can dilute blood sodium. Spread fluids through the day and let thirst and urine colour guide you rather than forcing large volumes.
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Educational estimate only, not medical or dietary advice. Calorie and weight-change figures are population averages; individual results vary. Consult a doctor or registered dietitian before starting a weight-loss, fasting or exercise plan.