Public health recommendations often suggest drinking eight cups (one cup = 8 oz.) of water a day.
Some fitness and weight loss specialists even recommend one ounce of water per two pounds of body weight.
However, researchers at UC San Francisco conducted a thorough review of the available evidence and found mixed results about the benefits of water consumption.
Their study, which analyzed 18 randomized controlled trials, was published in JAMA Network Open in late 2024.
The Verdict? There Isn’t One
The researchers concluded that while drinking enough water can have specific health benefits, the overall evidence is limited.
This includes evidence that people who want to lose a lot of weight should drink one ounce of water per two pounds of body weight.
For example, a 250 pound woman drinking 15 and a half cups a day!
No, forget that if you have a lot of weight to lose.
The researchers found that adequate water intake can help prevent kidney stones, assist with weight loss and reduce the frequency of migraines, urinary tract infections (UTIs) and too-low blood pressure.
However, not all benefits were equally supported across different groups.
Kidney Stones
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One of the strongest findings was that drinking sufficient water can significantly reduce the risk of kidney stones.
Several studies showed that drinking eight cups (one gallon) of water a day decreased the chances of developing another kidney stone.
Weight Loss
The research also indicated that drinking about six cups of water a day could help with weight loss in adults, though a study involving adolescents did not show the same result.
Despite this, the authors noted that drinking water before meals could be a simple and cost-effective way to address obesity.
For example, lemon flavored water sweetened with Stevia can help rid the desire for a sugary snack.
Migraines
The study also found that drinking more water helped prevent migraines.
Adults who had recurrent headaches reported feeling better after increasing their water intake over three months.
Diabetes
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Additionally, increased water consumption appeared to be beneficial for diabetics, as drinking four extra cups a day helped lower blood glucose levels.
Urinary Tract Infections
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For women suffering from recurrent UTIs, drinking an additional six cups of water a day reduced the number of infections and increased the time between occurrences.
Blood Pressure
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Another benefit of drinking more water was observed in young adults with low blood pressure.
Increased water intake helped raise blood pressure to a healthier level.
Water and Intense Exercise
The American Council on Exercise recommends drinking an additional 16-32 ounces of water for every hour of vigorous exercise to replace the fluids lost through sweat.
This means that on workout days, you should aim for about 10-12 cups of water, which includes your usual daily intake.
But also keep in mind the aforementioned information from the UC San Francisco study.
Of course, by all means drink water when you are thirsty rather than trying to tough it out.
There Is No Template
However, the study emphasized that water consumption should not be a one-size-fits-all solution.
For people who experience frequent urination, drinking less water might be beneficial.
While dehydration can be harmful, especially for those with a history of kidney stones or UTIs, drinking the right amount of water depends on individual health needs.
Lorra Garrick is a former personal trainer certified through the American Council on Exercise. At Bally Total Fitness she trained women and men of all ages for fat loss, increased strength, muscle building, fitness and improved health.
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