Do I really need 8 glasses of water a day? We tapped Sacramento experts for hydration tips

The Abridged version:

• Sacramento-area experts debunk the “eight cups a day” water rule, exploring concrete ways to make sure you’re adequately hydrated.
• Nutrition can help you reach your hydration goals. Reach for foods and drinks such as fruits, vegetables, soups, tea and even coffee to increase your fluid intake.  
• In a goal-oriented world, an expert explains why people struggle to do what’s good for them and gives tips for keeping their New Year’s resolutions.

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“Drink more water” is a common New Year’s resolution, but how much is enough, and is there any truth to the long-standing “eight cups a day” rule?

From hydration apps and smart bottles to water flavor packets and large reusable flasks, getting your water in is a popular wellness trend. Baback Roshanravan, a general nephrologist at the UC Davis Health Department of Internal Medicine, warns that relying on a one-size-fits-all approach to hydration, such as the “eight cups a day” rule, ignores the complexities of a person’s body.

You’re not only taming thirst when you drink water, but also helping to regulate body temperature, lubricate joints and aid in removing waste, according to the Cleveland Clinic, an academic medical center.

On average, water makes up approximately 60% of the body, with vital organs such as the brain, heart, lungs and kidneys largely dependent on it to do their jobs. Dehydration can happen to anyone, with severe cases leading to kidney complications, electrolyte imbalances and shock.

“Nobody is encouraging people to go out and drink a gallon of water; that’s a little excessive,” said Roshanravan, who treats adult patients with chronic kidney disease. “Drinking to a point of replenishing your thirst is always the best strategy.”

Here are tips for staying hydrated, with considerations around physiological factors, diet and mental health:

How much water should I drink daily?

Leslie Kaneko, a registered dietitian with Dignity Health Mercy Medical Group in Sacramento, said hydration is a big problem among her patients.

“A lot of people, just for whatever reason, are not drinking enough (water),” she said. “I rarely find somebody that is drinking too much.”

Both Kaneko and Roshanravan agree that your daily water intake depends on several factors, such as activity level, medical history and the climate in which you live.

Kaneko said that while the amount of water you should consume daily is purely individual, hydration guidelines are helpful because they at least provide people with some direction. Without them, she said, “people are just not going to really know.”

There are numerous fluid guidelines, one of the most popular being from the National Academies of Sciences, Engineering and Medicine, which suggests 2.7 liters (11.4 cups) for women and 3.7 liters (15.6 cups) for men. That’s the combined recommendation for both food and drinks.

The 8×8 water rule suggests that drinking eight 8-ounce glasses — or cups — of water daily provides proper hydration, but Roshanravan said that the guideline lacks scientific evidence. Instead, he said, focus on the following to maintain adequate hydration:

• Drink when thirsty.
• Replenish your body’s electrolytes after intense physical activity.
• Maintain a pale-yellow colored urine.
• Eat a balanced diet.

Kaneko said she also encourages her patients to start and end the day with water and reach for it during mealtimes as well. Another good rule of thumb, she said, is to drink 4 to 6 ounces of water once every hour during your workday.

According to the Mayo Clinic, an academic medical center, thirst isn’t universally the best indicator that you need water. Some people, primarily older adults, reach dehydration before they feel thirsty. 

Certain conditions require more fluids, such as vomiting and diarrhea, fever, extreme weather and intense exercise.

Signs of dehydration

Dehydration can manifest in several ways, with symptoms differing based on age. For adults, it could look like the following, according to the Mayo Clinic:

• Dark-colored urine.
• Feeling tired, dizzy or confused.
• Feeling extremely thirsty.
• Urinating less than normal.
• Sunken facial features (eyes and cheeks).
• Skin that doesn’t flatten instantly after being pinched.

Signs of dehydration in children are similar to adult cases, with the addition of a rapid heart rate, dry mouth and crying without tears.

For some people, Kaneko said, dehydration can also cause constipation, dry and itchy skin, and headaches. 

Hydration and food

Your daily food habits may already be contributing to your hydration goals, with roughly 20% of your daily fluid intake coming from your meals, according to the Mayo Clinic. 

“Hydration is important, but so is a balanced diet,” said Roshanravan, adding that foods contain both water and electrolytes, two components the body needs to retain hydration.

Your body replenishes electrolytes from foods and drinks, then your kidneys filter the excess through your urine. You also lose electrolytes through sweat.

Kaneko said foods such as fruits, vegetables and soups contribute to daily fluid intake. Even tea and coffee can aid in hydration. 

According to Harvard Medical School, the following foods have high water content:

• Vegetables (asparagus, carrots, broccoli, cabbage, celery, zucchini, spinach, iceberg and romaine lettuces and peppers).
• Fruits (cucumbers, strawberries and watermelon). 
• Dairy (milk).

Sweet potatoes, lentils, Greek yogurt and cooked shrimp and salmon are also packed with water, according to Harvard Medical School.

“You can’t replace all the water that you need based on those foods, but you can’t discount the amount that you get from the diet,” Roshanravan said.

Is caffeine dehydrating?

Coffee contains caffeine, which has diuretic properties, but shouldn’t cause dehydration when consumed in moderation — especially since it’s made mostly of water, Roshanravan said.

If you drink coffee daily, Kaneko said, you’re less likely to feel the diuretic effects — but they’re still there and adults should be conscious of how much caffeine they intake. 

“I don’t want people to think they can have eight cups of coffee a day and not get a diuretic effect,” Roshanravan said. “They will get a diuretic effect and need to pee.”

According to the U.S. Department of Agriculture, people across the U.S. typically consume caffeine through coffee, tea and soda. Healthy adults can generally have 400 milligrams of caffeine per day without dangerous, negative side effects.

The limit should be lowered for adults with certain medical conditions, Roshanravan said, such as high blood pressure or irregular heart rhythm. Research shows that consuming high amounts of caffeine may increase your risk for cardiovascular disease.

Possible health risks exist for young children who consume caffeine and no safe limit has been determined, according to the federal dietary agency.

Why we struggle to do what’s good for us

Building healthy habits has become popular in recent years, with each trip around the sun reviving the “new year, new you” mantra.

Lori Roberto, a licensed clinical psychologist in the Sacramento area, said whether your goal is to drink more water or something else, be curious, flexible and patient with yourself. Often, she said, people struggle to do what’s good for them because humans are complicated and fallible.

The intention-behavior gap, defined as the psychological disconnect between translating a plan into action, is “very human,” said Roberto, who specializes in health psychology and clinical hypnosis. Research shows that intention alone rarely drives health behavioral changes. Factors such as motivation, triggers and capacity inspire successful change in therapeutic spaces.  

“People have a lot of motivation to do things, but we do tend to falter, and for a lot of different reasons,” Roberto said, adding that some people struggle to implement new habits because they’re too rigid or unrealistic in their process for change.

In reality, Roberto said, humans have a “limited capacity to make change at any given time,” so be specific and realistic about your goals.

People are more likely to follow through on a task when their environment is conducive to reaching their goal, Roberto said. This could look like setting water by your sink to drink after brushing your teeth or choosing your favorite bottle to carry with you on errands to get more water in.

Another tip: Pairing a new habit with an established one may make the process more pleasant.

“I think especially at New Year’s, you know, people make a lot of goals … and they just abandon it all,” Roberto said. “We just really need to be gentle with ourselves and kind of realistic about, you know, what’s feasible and why it’s important. 

“And we’re not going to get it all 100% right.”

Brianna Taylor is an audience engagement reporter for Abridged, covering health and wellness.