Sugary drink sales bans have been somewhat less controversial than soda taxes, which have had mixed results. A study in Berkeley, Calif., found that sugary drink consumption fell and water consumption rose three years after the city implemented a soda tax. But another recent study found no significant overall declines in consumption in Philadelphia and Oakland in response to soda taxes there. In Philadelphia, the largest city with a soda tax, consumption of soda in particular did fall, and children who were heavy consumers of sugary beverages reported drinking less. But residents also reported buying more sugary beverages in neighboring towns that did not have soda taxes.

U.C.S.F., a health sciences center with more than 24,000 employees, implemented its sales ban in 2015. The university removed all sugar-sweetened beverages from cafeterias, food trucks and vending machines on its campus and installed more water stations. Fast food chains like Subway and Panda Express on its campus agreed to stop selling the beverages as well. One exception was made for 100 percent fruit juices, which contain natural sugars but have no sugar added to them. The university does not forbid anyone from bringing their own sugary beverages on campus, but they will find only bottled water, diet drinks, unsweetened teas and 100 percent fruit juices for sale.

To examine the impact of the sales ban, the researchers recruited a diverse group of 214 campus employees and then followed them, regularly taking blood samples and measuring things like their weight, soda intake and waist sizes. The study was funded by the University of California, U.C.S.F. and several philanthropic groups, including the Robert Wood Johnson Foundation and the Laura and John Arnold Foundation, which has given money to support taxes on sugary beverages.

At the outset, the researchers focused on enrolling a lot of lower-income service workers because they tended to drink the most sugary beverages. On average, the employees recruited for the study drank the equivalent of three cans of soda per day. One group that had an especially high sugar intake was cafeteria workers, the result of an “open tap” policy that allowed them to drink freely from the dining hall soda machines, said Dr. Epel.

“While that sounds like it was a favor to them, it was actually detrimental to their health,” she said. “This subgroup of workers tended to have a heavier B.M.I.”

Dr. Epel and her colleagues split the workers into two groups. One was assigned to undergo a brief motivational intervention that was modeled on standard alcohol interventions: They met with a health educator who talked to them about the health effects of sugar and showed them how much they were ingesting each day using sugar cubes in a cup. The educator helped them set goals and occasionally called them to check in. The second group of workers served as controls.

After 10 months, the workers in both groups cut their intake of sugary drinks to 18 ounces a day, down from about 35 ounces. While there was no overall change in their B.M.I., they had reductions in two measures of abdominal fat, including their waist sizes, which shrank by an average of 2.1 centimeters. Dr. Epel said this was because sugar intake is strongly linked to belly fat. “The type of fat that we store in the liver and in the abdominal fat tissue is very sensitive to sugar,” she said.