How much water to drink on a GLP-1: why hydration matters

If you are considering a GLP-1 medication for weight loss, you may know that dehydration is a possibility. So, how much water do you actually need to drink?

Unfortunately, there is no clinical guideline for how much water to drink on GLP-1 medications. Individual hydration needs vary depending on body type, activity level, and other factors.

Below, learn why hydration is important on GLP-1s and how to stay hydrated on a GLP-1 — including how much water to drink on Wegovy (semaglutide), Ozempic, (semaglutide), Zepbound (tirzepatide), or any other GLP-1.

There is no clinical guideline for how much water to drink on a GLP-1, but the general hydration recommendation for adults is:

• 2.7 liters (91 ounces) of water per day for women, from beverages and food

• 3.7 liters (126 ounces) of water per day for men, from beverages and food

A common rule of thumb is that about 20% of daily fluid intake comes from food. Based on that estimate, many adults need roughly 2.2–3.0 liters, or about 9–13 cups, of fluids from beverages each day.

That said, general recommendations are a good start, but daily water needs vary from person to person. Fluid needs may depend on overall health, age, body weight, activity level, and air temperature and humidity.​

Another helpful point: you do not need to stick to plain water to hit hydration goals on a GLP-1. Sparkling water, other unsweetened liquids, broths, and even water-rich foods count toward total daily water intake.

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Hydration is extra important on GLP-1s because some people drink less when they feel less hungry. Plus, side effects such as diarrhea and vomiting can quickly deplete body fluids.​

GLP-1s work by suppressing appetite and slowing digestion, meaning people feel full faster and stay full for longer. Some people may simply not feel thirsty and forget to hydrate. Others may feel too full to drink a full glass of water.

Food is also a meaningful source of daily fluids — fruits, vegetables, soups, and other water-rich foods can account for a notable share of total water intake. Because GLP-1s reduce overall food volume, people may unknowingly lose this secondary fluid source as well, on top of drinking less.

And then there are the side effects.​

• Nausea is one of the most common side effects of GLP-1 medications. It can turn drinking and eating into an uncomfortable experience.

• Diarrhea is also a common GLP-1 side effect, and it can cause rapid fluid loss.

• Vomiting causes fluid loss before the body has a chance to absorb what was consumed. Without replacing those fluids, dehydration can follow.

In short, GLP-1s can increase the risk of dehydration in several ways, so people taking these medications should make hydration a priority.

Staying hydrated on a GLP-1 is important to prevent dehydration, and may even  support healthy weight loss. Strategies such as sipping throughout the day and eating water-rich foods can help keep the body hydrated throughout treatment.

Schedule hydration breaks

GLP-1s can make people feel less hungry and or more full, so it can be easy to forget to drink fluids,so it is easy to simply forget to drink water. Scheduling hydration breaks ensures that you drink throughout the day, even without thirst cues.

Some ideas:

• Set alarms that remind you when it's time to drink.

• Use a measured water bottle so you can monitor your intake as the day goes on.

• Use a hydration app to send you water break reminders.

• Ask a friend or family member to hold you accountable for how many ounces you drink each day.

Manage nausea (and other side effects)

Nausea is common on GLP-1s, but there are ways to minimize or manage it so that drinking water does not make you feel like you are about to throw up.

Strategies for managing nausea include:

• Eating smaller, more frequent meals

• Avoiding fried, greasy, and sugary food

• Eating more bland foods, such as toast, crackers, baked chicken or fish, and potatoes or oatmeal

For most people, nausea is worse when starting treatment or increasing a dose and may improve over time. If nausea is persistent or severe enough to consistently prevent eating or drinking, it is worth mentioning to a healthcare provider, who may adjust the dose or suggest additional strategies.

People struggling to stay hydrated due to diarrhea or vomiting can also benefit from lifestyle changes. Strategies may include sipping water throughout the day, replacing electrolytes when needed, avoiding foods or drinks that trigger symptoms (dairy is a common culprit in people with lactose intolerance), and limiting caffeine and alcohol.

​In all cases, don’t hesitate to reach out to your healthcare provider if GLP-1 side effects are impeding your life, including staying hydrated.

Sip between meals

Stay hydrated by taking small sips of water throughout the day, between meals. That way, you can focus on nutrition rather than hydration at breakfast, lunch, and dinner.

People on GLP-1s feel full much more quickly than they did before starting the weight loss medication. For anyone feeling overly full or nauseated, getting enough food and fluids at meals can be tricky, so try separating the tasks of eating and drinking.

Try herbal tea

If you are struggling to stay hydrated due to medication-related nausea, try sipping herbal tea throughout the day. It may feel gentler than plain water for some people.

Research suggests tea can be just as hydrating as water. Herbal teas such as ginger, chamomile, and peppermint may help relieve nausea, though this has not been specifically proven for GLP-1-related nausea.

Play with temperatures and flavors

Plain cold water is not the only way to hydrate. If you are more likely to drink sparkling water, flavored water, tea, no-sugar-added juice, or sports drinks, stock up on those instead. Keep in mind that juice and sports drinks can still contain sugar and calories.

Some people with nausea find it easier to drink ice-cold beverages or suck on ice chips. Then again, one small study found that people rehydrate best when water is slightly cool, but the best temperature is usually the one that helps you drink enough.

Eat hydrating foods

Water-rich foods can help you stay hydrated at mealtimes or when the thought of drinking a full glass of water makes you feel sick.

Try taking small, mindful bites of these hydrating foods:

• Cantaloupe

• Watermelon

• Lettuce

• Cabbage

• Celery

• Spinach

• Yogurt

• Oranges

• Carrots

• Soups and broths

Watch out for these general signs of dehydration on a GLP-1 (or anytime, really):

• Feeling thirsty

• Decreased urine output

• Dry mouth or tongue

• Dark yellow urine

• General weakness or fatigue

• Dizziness

Contact your healthcare provider if you cannot keep fluids down, have severe or prolonged diarrhea, or feel faint or weak. If you cannot replace lost fluids, dehydration can quickly become severe. Seek urgent care if you faint, feel confused, have very little or no urination, or cannot replace lost fluids.

Get started

Wondering how much water to drink while losing weight on a GLP-1? Unfortunately, there is no one-size-fits-all answer. But that does not mean hydration should be an afterthought.

Hydration needs can shift as the dose changes or side effects come and go, so the "right" amount today may not be the right amount next month. Paying attention to how the body responds rather than chasing an exact number is often the most sustainable approach.

Here’s the recap on why and how to stay hydrated on GLP-1 medications:

• GLP-1s may increase the risk of dehydration. GLP-1s can lead you to drink less and can cause fluid loss from diarrhea and vomiting.

• Make hydration a priority if you’re on a GLP-1. Strategies include scheduling hydration breaks, sipping between meals, managing nausea, and getting creative with hydration by sipping herbal tea and broth or eating water-rich foods.

• Aim for 2.7–3.7 liters of total water from drinks and food per day regardless of GLP-1 use. That’s the general rule of thumb for adults, according to the National Library of Medicine.

• Know the signs of dehydration. These include decreased urine output, dark urine, dry mouth, dizziness and fatigue.

• Tell your healthcare provider if you are worried about dehydration. If nausea, diarrhea, or vomiting are severe or persistent, your healthcare provider may recommend a dose adjustment or another strategy.