(CNN) On average, Americans consume more than 40 gallons of sugary drinks each year. In an effort to change what is apparently an everyday behavior for many people, public health researchers at the University of California, San Francisco took a bold step. They persuaded every vendor on campus to stop selling beverages with added sugar.

"It's a sales ban, which means the university has opted out of the business of selling and profiting off of sugar-sweetened beverages," said Laura Schmidt, a professor of health policy in the School of Medicine.

Schmidt spearheaded the voluntary sales ban, which took effect on July 1, 2015, yet required three years to get everybody on board. "It's a very, very big institution," she said, adding that she and her colleagues went "door to door" to meet with people.

Visitors are free to bring in whatever beverage they want -- or leave campus to buy it. The one new rule is that every food source on campus, from the Subway restaurant to the vending machine in the lounge, will not sell the usual sugary beverages.

"The definition of sugar-sweetened beverages is pretty standard at this point: It's beverages with added sugars," Schmidt explained. These beverages include syrupy coffee drinks, milkshakes and "natural" juices containing fructose.

However, UCSF has not banished diet drinks, including zero-calorie sodas, or 100% fruit juices from campus -- for good reason.

Often, people find diet beverages as a good way of coping with sugar cravings at trigger times, explained Schmidt. And though there is accumulating evidence that diet drinks may be linked to glucose intolerance, there's not enough evidence -- at least not yet -- to include these beverages in the ban.

SugarScience

"The happy surprise of it all is people actually realize they can reach for this delicious tea with a hint of mint in it, and it's got no sugar in it, and it tastes great," Schmidt said.

a UCSF-led initiative formed in 2014, she should know. SugarScience has collected and analyzed thousands of research studies examining the health impacts of sugar over the past two years. Though she hopes to have a positive impact, Schmidt is not aware of any studies examining whether sugar taxes or bans have an impact on health. As a member of SugarScience a UCSF-led initiative formed in 2014, she should know. SugarScience has collected and analyzed thousands of research studies examining the health impacts of sugar over the past two years.

So, with the sales ban in place on the UCSF campus, Schmidt and her SugarScience colleagues decided to design their own study.

They enlisted the help of more than 2,500 university employees and identified a subsample of 214 people who were heavy consumers of added-sugar beverages, drinking a liter or more a day. With this group, they designed a "sub-study" in tandem with the larger study.

The purpose of the smaller study "is to see if we can actually move the dial by using a workplace policy," Schmidt said.

For this smaller group, the researchers performed a complete physical, including weight, height and blood pressure measurements. Blood tests were performed as well. These employees returned for a physical six months after the sales ban began and once again at 12 months.

"We're in the process of analyzing that data right now," Schmidt said, though she said that after six months, a 25% decline in consumption had occurred among those who drank the most sugary beverages.

She is eager to see the latest results, noting that if she and her crew can show changes in consumption sustained over a year, "you know you're making an impact."

Why now?

In the past, amid epidemics of cancer and tobacco-related diseases, the medical system seemed to be the last, not the first, to raise the alarm, according to Schmidt. In fact, hospitals used to openly sell cigarettes, even delivering packs to patients in bed.

Today, there's a crisis of obesity, so it's an opportunity for the public health sector to act as the leader, not a follower, she suggested.

Public health officials across the nation, including Dr. Bruce Lee , director of the Johns Hopkins Global Obesity Prevention Center at the Johns Hopkins Bloomberg School of Public Health, see her point.

"A third of our population is obese. Two-thirds is overweight or obese. There's been a lot of studies that have shown that leads to both immediate, as well as long-term problems," Lee said. Estimates suggest that one in four children will develop diabetes in their lifetimes.

"Diabetes is just one chronic disease that is associated with obesity," Lee said. Many other conditions, including cardiovascular disease, multiple cancers and mental health disorders, also are associated with obesity.

"It seems like every year, we're seeing more and more connections between obesity and different health problems," he said. "The thought is, obesity is the result of things being off-kilter with the body. So it's a precursor to many different types of problems."

Meanwhile, it's obvious to patients that hospitals and health care systems openly offer junk foods, soda and sugar-sweetened beverages. The message that obesity is unhealthy is getting lost. To change this, an increasing number of hospitals and health systems are moving toward at least providing more healthy options, said Lee.

Though public health officials are mostly in agreement with the UCSF sales ban and similar policy changes, Lee cautions that it is necessary to provide alternatives for people and execute the policy successfully. Some failures have occurred in schools, he noted, where "kids just leave the grounds" in order to get junk food that has been banished from the school environment.

"It's important whenever you make these changes that you think about what might be the compensatory responses," Lee said.

Sugar allowance and differing opinions

There are 61 names for sugar used in food processing that appear on ingredient lists. Added sugar is not the same as naturally occurring sugars in fruit, vegetables or other foods that don't have ingredient lists. Added sugar is any sugar put into food or beverages during processing, during preparation or at the table, according to the website for SugarScience There are 61 names for sugar used in food processing that appear on ingredient lists. Added sugar is not the same as naturally occurring sugars in fruit, vegetables or other foods that don't have ingredient lists.

Sugar limits apply to added sugar only. Although there is no single government-recommended daily value for sugar in the United States, the American Heart Association advises limiting added sugar to less than 6 teaspoons (or 25 grams) a day for women, 3 to 6 teaspoons (or 12 to 25 grams) each day for children, and 9 teaspoons (or 38 grams) a day for men.

Among SugarScience's most important discoveries: There are clear links between sugar consumption -- particularly in liquid form -- and diabetes (independent of obesity), cardiovascular disease and liver disease.

Even if a sales ban has potential benefits, not everyone agrees with health policy wielded like a hammer.

In 2012, when New York City attempted to restrict restaurant sales of large sugary drinks, an appeals court ruled the regulation "arbitrary and capricious" adding the board of health "failed to act within the bounds of its lawfully delegated authority."

Schmidt emphasizes that the UCSF ban was voluntary. Every vendor on campus, as well as the chief financial officer, willingly agreed to go along with it, she said.

"Everyone was worried they'd lose money, but no one lost money," she said.

The American Beverage Association , an industry group, is nonplussed by the ban.

"America's leading beverage companies offer a wide variety of beverages -- including no- and low- calorie and smaller portion sizes -- to suit all tastes and lifestyles," said Lauren Kane, a spokeswoman for the organization. "These companies are always innovating to meet consumer preferences, and in fact, nearly half of the beverages they sell contain zero calories."

As far as the association is concerned, universities should feel free to choose the beverages they want to offer.

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In fact, an observer casually walking around campus would see nothing unusual. Everything still looks pretty much the same, Schmidt said: "The shelves are filled with stuff. It's just stuff that isn't loaded with sugar."

"Our current food environment is rigged to make the unhealthy choice the easy choice," Schmidt said, adding that in many retail operations the placement and pricing of sugary beverages is intended to create more sales.

In the end, the sales ban is "not moralistic" or about trying to "constrain people," she said; it's really just that a health institution should not be profiting by selling unhealthy beverages. That said, she understands people's concerns: "We like our freedom. We want our individual choice. I don't want anyone to telling me what to eat. I'm an American."

By helping to "make the healthy choice the easy choice," Schmidt says she increased people's options.