About a fifth of the water you take in normally comes from food, so eating less on a GLP-1 means drinking a little more. Choose your sex and how much you exercise for a daily target in litres and glasses.
Choose female or male to see how much to drink a day.
Fluid, fiber and electrolytes work together, especially when side effects hit. Get the rest of the picture.
Or get new recipes & tips by email:
European guidance from EFSA puts total water at 2.0 litres a day for women and 2.5 for men, and assumes 80% of it comes from drinks: 1.6 and 2.0 litres. The US National Academies recommend more, 2.7 and 3.7 litres of total water, with drinks providing about 81% in US surveys: roughly 2.2 litres for women and 3.0 for men. The calculator shows the range between the two.
It then adds a small top-up, because food normally provides about a fifth of your water and GLP-1 medications cut how much people eat by 16 to 39%. For exercise, it uses the National Academies' example of moderately hard exercise in the heat, about 0.7 litres of sweat an hour, as the most you'd need to add. Both sets of guidance give one figure per sex rather than scaling with body weight; what changes your needs most is heat, exercise and illness.
A sensible target is about 1.7 to 2.3 litres of drinks a day for women and 2.1 to 3.2 litres for men. That's a little more than the usual guidance, because you get less water from food when you eat less. Drink more on exercise days, in hot weather and when you're ill.
Yes. Water, milk, tea and coffee all count, and the US National Academies found that caffeinated drinks contribute to hydration as much as other drinks.
You eat less, so you get less water from food. Feeling full can make you drink less too. And side effects like vomiting and diarrhea lose fluid; dehydration from them can harm your kidneys, so it's worth staying ahead of it.
Your pee is the easiest check: aim for a clear, pale yellow. Dark yellow pee is a sign to drink more.