Doesn’t it seem like everyone you see has a cute reusable water bottle sticking out of their bag? Indeed, it’s become much easier to stay hydrated in the last few years—and yet, people still struggle. On top of that, we think we know how much water to drink per day, when in fact that goal number of ounces should actually be a little different for everyone. In fact, experts say it can even vary for you based on what you do in any given day.

Meet the experts: Stephani Johnson, D.C.N., R.D.N., is an adjunct professor in the Department of Clinical and Preventive Nutrition Sciences at Rutgers University; Christy Brissette, M.S., R.D., owner of 80 Twenty Nutrition; Devon Wagner, R.D., M.S. a registered dietitian at The Ohio State University Wexner Medical Center; Eric Adkins, M.D., is an emergency medicine physician at the Ohio State University Wexner Medical Center.

Here, we’re breaking down everything you need to know about H2O intake, including what the recommendations say, the factors that could influence your individual hydration goals, and more.

How much water should you drink a day?

The U.S. National Academies of Sciences, Engineering, and Medicine has very clear guidelines on how much water to drink a day.

According to the organization, women should aim to have 11.5 cups (92 ounces) of fluids a day, while men should have 15.5 cups (124 ounces) of fluids a day. It’s important to point out that those fluids come from food and drink—and about 20% of your daily fluid intake usually comes from foods.

“However, many things can impact fluid needs,” said Stephani Johnson, D.C.N., R.D.N., an adjunct professor in the Department of Clinical and Preventive Nutrition Sciences at Rutgers University. Meaning, you could be over- or under-hydrating if you just follow these guidelines and don’t pay attention to your body’s cues about hydration.

The problem with the advice to drink 8 glasses a day

There are a few potential issues with the advice to drink eight glasses of water a day. One is that there’s so much variability in glass size. “Eight glasses may be enough, but it depends on the size of the ‘glass’ and individualized needs,” Johnson said. Meaning, you’re going to be taking in wildly different amounts if you’re using 8-oz glasses vs. 16-oz glasses as your measurement. Advice to drink eight glasses a day isn’t wrong—it’s just not very precise.

If you use a cup as your measurement, you’re then looking at 8 ounces per glass. If you aim to have eight of those glasses, you’re only at 64 oz of water a day. That’s well under the recommended 92 oz of water a day for women and 124 oz a day for men.

Still, if you aren’t currently drinking enough water at the moment and need an easy guide to follow, Johnson said aiming to have eight glasses of water a day is a good starting point.

Factors that influence how much water you need per day

Breaking hydration goals down by sex is one way to look at it, but the reality of what you actually need is much more complex. Johnson said that these factors can influence how much water you need:

Sex: Men usually—but not always—require more fluids than women because they tend to have greater muscle mass, which holds more water. Sweat: You lose fluids when you sweat, and the amount of fluid loss is based on your climate, temperature, and physical activity level. “The more you sweat, the more water you need,” Johnson pointed out. Age: Your total body water content decreases as you get older, your sense of thirst sensation drops, and your kidney function becomes less efficient, per UCLA Health. That tends to increase your hydration needs with age. Body size: People who are bigger lose more water because they have a larger skin surface area. They also require more fluids for overall bodily functions. “To get a rough idea of how much water you need, divide your weight in pounds in half,” said Christy Brissette, M.S., R.D., owner of 80 Twenty Nutrition. “That’s how many ounces of water you should aim to drink per day.” Diet: You may need less fluids if you eat foods with a high water content, like melons, cucumbers, or soups. But loading up on high-fiber foods may mean you need to drink more. “Eating a high fiber diet also increases your fluid needs because fiber absorbs water,” Brissette said. Alcohol: Alcohol is a diuretic, which means it makes you pee more. It ultimately increases your hydration needs. Medical conditions: Some conditions, like those that cause diarrhea, will raise your fluid needs, according to the Mayo Clinic. Others, like congestive heart failure, may reduce them, per the Cleveland Clinic. Breastfeeding and pregnancy: Nursing moms have higher fluid needs, which can vary based on how much milk they produce. Pregnant people also need more fluids than others, Brissette said. Why hydration is important to overall health

Your body is made up of about 55%-60% water. With that, it’s important to stay well hydrated for everything to function properly in your body, said Devon Wagner, R.D., M.S., a registered dietitian at The Ohio State University Wexner Medical Center.

“Digestive function, skin health, kidney function, and regulating body temperature all require adequate fluid intake,” Wagner said.

Water is also required for your body to move nutrients around and to flush out waste, Brissette said. Being well hydrated protects your organs and tissues, lubricates your joints and the spinal column, and plays a “vital role” in supporting brain function, Wagner added.

“Without sufficient water intake, many bodily processes become impaired, with the severity of health consequences depending on the degree of dehydration,” she said. “Adequate hydration is essential, but there are negative health outcomes associated with over-hydration, so more is not always better.”

Can drinking enough water help you lose weight?

Drinking water may help you lose weight, but it’s not a given. “Thirst is sometimes mistaken for hunger, so having a glass of water before eating can be a helpful way to pause and determine whether you’re actually hungry,” Brissette said.

Being dehydrated can also cause what Wagner called “pseudo-cravings,” especially for things that are salty or sweet. As a result, doing your best to have enough water in your day may help lower the odds you’ll deal with urges to eat less healthy foods.

If drinking more water is the only thing you do for weight loss, Brissette said you’re unlikely to see a significant change. But if you’re hydrating well, being active, and focusing on good nutrition, it can help support your weight loss goals.

Do drinks other than water help with hydration?

While nutritionists agree that water is your best bet for hydration, it’s not the only option. Wagner suggested looking for drinks that are very low calorie, like herbal tea, making sure to limit caffeine. “Caffeine pulls fluid out of our bodies and can increase our risk of dehydration if drinking in excessive amounts,” she said.

If you’re sweating a lot, it’s OK to reach for something with electrolytes, like a sports drink, said Eric Adkins, M.D., an emergency medicine physician at the Ohio State University Wexner Medical Center. (This just shouldn’t be the only thing you drink.) “Coconut water is an acquired taste, but it can help when you put a hard workout in and are feeling depleted,” he said.

Again, certain foods can help with hydration, too, like cucumbers, watermelon, asparagus, celery, strawberries, and zucchini.

How to tell if you’re drinking enough water

Keeping tabs on how much water you drink in a day can help you stay on track. But Dr. Adkins pointed out that it’s best to listen to your body. “Everyone asks how much water they should be drinking, but a lot depends on your environmental circumstances and your own body,” he said.

That’s why he generally recommends paying close attention to the color of your urine. “If it looks dark orange or a darker yellow, it’s an indication that you’re not getting enough water,” Dr. Adkins said. On the other side, he says you may be overdoing it if it constantly looks like you’re urinating out water. One caveat, per Brissette: If you’re taking a multivitamin or B vitamins (especially riboflavin), your pee might look bright yellow regardless of how much you drink. “That’s completely normal and a sign that your body is getting rid of any extra riboflavin it doesn’t need,” she said.

Again, the amount of water you should drink a day is a little variable. But paying close attention to what lands in the toilet bowl and making adjustments based on that can go a long way toward making sure you’re well-hydrated.

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