What Happens When You Drink Too Much Water?

We have always been told to drink water and keep ourselves hydrated. But did you know there is also a drinking limit for your body and over drinking water may not be a good thing for your body and your health.

A recent study published in JAMA Network Open explores the conventionally believed thought that drinking more and more water is universally beneficial. The study is conducted by researchers at the University of California, San Francisco (UCSF), and it reviewed the clinical trials to assess whether increasing water intake offers any significant health benefits.

Study's senior author and chair of UCSF's Department of Urology, Dr Benjamin Breyer, said, “For such a ubiquitous and simple intervention, the evidence hasn’t been clear, and the benefits were not well established, so we wanted to take a closer look".

Water makes up about 60% of the human body and plays a critical role in essential functions like:

Dehydration can disrupt these processes, but does drinking more water beyond daily requirements truly enhance health? Here’s what the study found.

Three studies showed that drinking 51 fl oz (1.5 L) of water daily before meals led to significantly more weight loss among overweight and obese adults over 12 weeks to a year, compared to control groups. However, a separate study found no weight changes when participants consumed 68 fl oz (2 L) daily for six months.

There were mixed results on people with type 2 diabetes. While one study showed a significant reduction in fasting blood glucose levels after participants drank water before meals for 8 weeks, another study found a slight increase in fasting blood glucose after participants drank water in the morning and before bedtime for 12 weeks. Which raised the question that the benefits noted in the first study may have stemmed from decreased food intake or weight loss.

Here too, we have conflicting results. One study showed improvement in migraine quality of life and fewer moderate headache days after increasing water intake. However, the results were not statistically significant.

Another trial involving fewer participants reported no notable effect on migraine intensity or frequency.

We all know that drinking water prevents UTI. In fact, a trial of 140 women prone to recurrent UTIs found that increasing water intake reduced UTI episodes and antibiotic use over a year.

However, there was a small study that found no significant change in urinary bacteria among women who drank more water. Interestingly, reducing fluid intake by 25% helped adults with overactive bladder experience fewer urges and nighttime trips to the bathroom.

Here, the evidences supported increased water consumption for reducing kidney stone risks. In one study, healthy adults drinking an additional 68 fl oz (2 L) of water daily had a lower risk of developing kidney stones. Another trial showed a significant drop in kidney stone recurrence over five years among those who increased water intake.

While drinking more water was associated with clear benefits in areas like weight loss and kidney stone prevention, the evidence for other conditions—such as headaches, bladder health, and diabetes—was less conclusive.

“The amount of rigorous research turned out to be limited, but in some specific areas, there was a statistically significant benefit,” said Dr. Breyer. “There isn’t a one-size-fits-all approach for water consumption," said Dr Breyer.