A new study, led by health professor Ruopeng An, suggests that getting kids to drink water with their school lunches could significantly reduce their chances of being overweight. This could, in turn, cut medical costs and indirect societal costs by $13 billion.

The research is a result of a nationwide expansion of a pilot program in New York involving over 1,200 middle and elementary schools. The study was carried out between 2009 and 2013. After water dispensers were put into schools, students were found to drink three times more water during their breaks and a year later, were less likely to be overweight.

The Centers for Disease Control and Prevention note that children are described as overweight when their BMI is at or above the 85th percentile and under the 95th percentile for other children of their age. 

Last month Majid Ezzati, a professor of global environmental health at Imperial College London, told CNN that over the past 40 years, obesity amongst children has risen, especially in low and middle-income countries.

"More recently, [obesity rates] have plateaued in higher-income countries, although obesity levels remain unacceptably high," he said.

“The nutrition profile doesn't change much when people increase their plain-water intake, but we do see a significant drop in their saturated fat and sugar intake," An said, according to Illinois News Bureau. 

"While there might potentially be some problems if children consume less whole milk, I would say those are probably minor in comparison with the costs associated with the skyrocketing rates of childhood overweight [sic] and obesity in the US," he continued.