Staying hydrated on a GLP-1

Why hydration matters more on a GLP-1

Hydration is important for everyone, but it becomes particularly important on GLP-1 medications for several reasons:

Reduced food intake = less water from food. A significant portion of daily fluid normally comes from food — fruits, vegetables, soups, yoghurt. When appetite is reduced, so is this hidden hydration source.

Nausea and vomiting cause fluid loss. If you are experiencing these side effects, you are losing fluids that need to be replaced.

Constipation is worsened by dehydration. GLP-1 medications commonly slow gut motility. Adequate fluid is essential to keep things moving.

Dehydration itself causes nausea and fatigue — which can be mistaken for (or worsen) medication side effects.

How much to drink

A general starting point for most adults is 1.5–2 litres of fluids per day (approximately 6–8 glasses). Your needs may be higher if you exercise, live in a warm climate, or are experiencing vomiting or diarrhoea.

A simple check: your urine should be pale yellow. Dark yellow or amber urine is a sign you need more fluids.

What counts as hydration?

• Water — the best option
• Herbal teas — a good alternative to plain water
• Diluted fruit juice — fine in small amounts (avoid high-sugar versions)
• Broth / soup — excellent for hydration when appetite is low
• Milk — counts towards fluid intake and adds protein
• Sparkling water — hydrating, but carbonation can worsen bloating for some

Does not count (or works against hydration):

• Alcohol — a diuretic that causes net fluid loss
• Large amounts of caffeine — moderate coffee and tea are fine, but excessive amounts can contribute to fluid loss

Practical strategies

Start the day with water. Drink a glass of water before your first meal — it sets a good tone for the day and helps with morning nausea.

Carry a water bottle. Having water visible and accessible is the simplest habit change that makes a measurable difference.

Sip throughout the day rather than drinking large amounts at once. Large volumes of liquid at once can worsen bloating and nausea. Small, regular sips are easier to manage.

Drink between meals, not with them. Large amounts of liquid during meals can worsen bloating and fullness. Try to hydrate between eating.

Set reminders if you forget. A phone alarm at regular intervals is a simple tool if you tend to go hours without drinking.

Flavour your water if plain water is unappealing. A slice of lemon, cucumber, or mint can make it more palatable without adding significant sugar.

Signs of dehydration

• Dark urine
• Headache (often one of the first signs)
• Fatigue
• Dizziness, especially when standing
• Dry mouth
• Constipation worsening

If you are experiencing vomiting and cannot keep fluids down, contact your prescriber. Oral rehydration solutions (available at pharmacies) can help restore electrolytes if you have been vomiting.

General information note

This guide provides general lifestyle information only — not medical advice. Individual fluid requirements vary based on body size, activity level, climate, and health status. Consult your healthcare provider if you have concerns about hydration or if you cannot keep fluids down.