Does water help you lose weight?

Water can help indirectly. Drinking water before meals can reduce appetite, and we sometimes confuse thirst with hunger. In addition, water has no calories and replaces caloric drinks. However, water alone does not burn fat; the thermogenic effect of drinking cold water is minimal. It is a useful complement in a weight-control strategy, not a solution on its own.

Water Intake Calculator — Daily Water Needs 2026

Q: Do soft drinks and coffee count as water?

Coffee, tea and other infusions contain water and contribute to hydration, although caffeine has a mild diuretic effect. Sugary soft drinks are not a good source of hydration due to their high sugar content. Natural juices and the water in fruit and vegetables do count. Ideally, most of your intake should come from plain water.

Q: Can you drink too much water?

Yes. Water intoxication or hyponatremia occurs when water is consumed in excess, diluting electrolytes, and can be dangerous. However, it is uncommon under normal conditions. Healthy kidneys can process up to 0.8–1 litre per hour. Drinking more than 3–4 litres a day without a medical or athletic reason is usually not necessary.

Science of hydration

Why is proper hydration important?

Water is involved in almost every bodily process, from temperature regulation to cognitive function.

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The 35 ml/kg rule

The most widely used base recommendation is 35 ml of water per kilogram of body weight per day. For a person weighing 70 kg, that equals 2.45 L. This rule does not account for physical activity or climate, which is why we add additional multipliers.

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Physical activity and hydration

Each hour of moderate-intense exercise can mean a loss of 500–700 ml of water through sweat. The calculator applies multipliers ranging from 30 ml/kg (sedentary) to 42 ml/kg (very active) to reflect these differences.

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Signs of dehydration

The body gives warning signs before you feel intense thirst. Pay attention to: dark or intense yellow urine, unexplained fatigue, headache, difficulty concentrating and dry mouth. Pale yellow urine is a sign of good hydration.

Quick reference

Daily water by weight — Moderate activity

Calculated with 35 ml/kg (moderate activity, normal climate). Adjust with the calculator for personalised values.

Weight	Litres/day	Glasses (250ml)	Hot climate
50 kg	1,75 L	7 vasos	2,25 L
60 kg	2,10 L	8 vasos	2,60 L
70 kg	2,45 L	10 vasos	2,95 L
80 kg	2,80 L	11 vasos	3,30 L
90 kg	3,15 L	13 vasos	3,65 L
100 kg	3,50 L	14 vasos	4,00 L
110 kg	3,85 L	15 vasos	4,35 L

Frequently asked questions

Questions about hydration

How much water should I drink per day?

The general recommendation is 35 ml per kilogram of body weight per day. For a person weighing 70 kg with moderate activity, this equals about 2.45 litres (approximately 10 glasses of 250 ml). Needs vary according to physical activity, climate, diet and health status. Use the calculator above to get your personalised figure.

Do soft drinks and coffee count as water?

Coffee and tea contain water and contribute to hydration, although caffeine has a mild diuretic effect. Sugary soft drinks are not a good source of hydration due to their high sugar content. Natural juices and the water in fruits and vegetables do count. Ideally, most of your intake should come from pure water or unsweetened herbal teas.

Can you drink too much water?

Yes. Water intoxication or hyponatraemia occurs when water is consumed in excess and electrolytes are diluted, which can be dangerous. However, it is uncommon under normal conditions. Healthy kidneys can process up to 0.8–1 litre per hour. Drinking more than 3–4 litres per day without a specific sporting or medical reason is generally not necessary.

When should I increase my water intake?

You should increase water intake when: you do intense physical exercise (add 500–700 ml per hour of exercise), you live in a hot or humid climate (+500 ml per day), you have a fever, diarrhoea or vomiting, you are pregnant or breastfeeding, or you consume many processed and salty foods.

Does water help with weight loss?

Water can help indirectly. Drinking water before meals can reduce appetite, and sometimes we confuse thirst with hunger. Also, water has no calories and replaces caloric drinks. However, it does not burn fat on its own. It is a very useful complement in a comprehensive weight management strategy, not a standalone solution.

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