Despite common health advice urging people to drink eight cups of water daily, the actual scientific support behind such recommendations remains surprisingly unclear. With hydration often tied to everything from energy levels to clearer skin, many individuals increase their water intake hoping to boost their health. But what does the evidence really say? That question motivated a group of researchers to conduct a thorough review of clinical studies, which are formal investigations with human volunteers, to find out whether drinking more or less water truly impacts health in measurable ways.
A team of scientists led by Professor Benjamin Breyer from the University of California, San Francisco carried out a detailed review of studies where participants were asked to change how much water they drank each day. The findings are published in the journal JAMA Network Open, a medical publication that shares peer-reviewed scientific research.
The team looked at studies that tested how drinking more or less water affected people’s health. These studies were conducted over the past twenty years and lasted from just a few days to several years. About half of them showed at least one clear health benefit from changing water intake, while the other half did not show much difference. Still, drinking more water often led to better results in two areas in particular: helping people lose weight and lowering the chances of developing kidney stones, a painful condition caused by mineral buildup in the kidneys.
One of the most encouraging results came from people who had a history of kidney stones. When these individuals were told to drink more water so they would produce more urine, they had far fewer kidney stone episodes. Similarly, in studies on weight loss, people who drank water before meals lost more weight compared to those who didn’t. “Increasing water intake before meals was linked to greater satiety, which means feeling full, and decreased calorie intake, which likely contributed to weight loss,” Professor Breyer explained, suggesting that water helped people feel fuller and avoid overeating.
Some smaller studies pointed to other possible health benefits. For example, people with type 2 diabetes, a condition where blood sugar levels are too high, who drank water before meals saw a meaningful improvement in their blood sugar levels. In another case, women who frequently experienced urinary tract infections, which are bacterial infections in the urinary system, had fewer episodes after drinking more water. “Given the low cost and minimal risk, these findings suggest that increasing water consumption could be a worthwhile intervention, meaning a strategy to improve health, to explore further,” Professor Breyer noted.
The review of Professor Breyer and his colleagues also highlights how staying well-hydrated might help in ways that are not immediately obvious. While not every result was statistically strong, meaning it didn’t always reach the level scientists require to rule out chance, the overall trend showed improvements in several areas. Because water is easy to access, safe, and inexpensive, it could be a simple and helpful addition to health routines for many people. Still, the researchers advise that more studies are needed to truly confirm these effects and understand how personal factors—like age, health condition, and usual hydration habits—might change how water intake works.
Altogether, Professor Breyer’s team’s review encourages a new look at water as more than just something we drink to stay alive. It suggests that water could also be a practical part of taking care of specific health conditions. While more research is needed, this study lays the foundation for scientists to continue exploring how daily water habits might help us stay healthier.
Journal Reference
Hakam N., Guzman Fuentes J.L., Nabavizadeh B., Sudhakar A., Li K.D., Nicholas C., Lui J., Tahir P., Jones C.P., Bent S., Breyer B.N. “Outcomes in Randomized Clinical Trials Testing Changes in Daily Water Intake.” JAMA Network Open, 2024; 7(11): e2447621. DOI: https://doi.org/10.1001/jamanetworkopen.2024.47621
About the Author
Professor Benjamin Breyer is a leading expert in urology and epidemiology, serving as a faculty member at the University of California, San Francisco. His work bridges clinical practice and public health research, with a strong focus on improving patient outcomes through evidence-based care. Professor Breyer has contributed significantly to studies exploring urinary health, lifestyle factors, and preventive strategies, particularly in understanding how everyday behaviors, like water consumption, can influence long-term wellness. Known for his collaborative and interdisciplinary approach, he often works alongside teams of clinicians, researchers, and data scientists to address practical health questions with scientific rigor. His research has been widely published in respected medical journals and has helped shape both clinical guidelines and public awareness. Beyond his academic achievements, Professor Breyer is recognized for mentoring the next generation of physicians and researchers, advocating for accessible and impactful healthcare solutions.
