When it comes to nutrition policy, we know about a lot of things that don’t work: Soda taxes andproximity to healthy foods, for example, have relatively shaky support in the public health literature. At the same time, we know we need something to work: The CDC projects that 42 percent of the country will be obese by 2030.

(Finbarr O’Reilly - Reuters)That makes it all the more exciting to find one policy that does seem to be working: California’s strict school nutrition standards — soda bans, low calorie foods in cafeterias and limits on fat content — appear to have had a significant impact on what teens there eat.

A study of about 700 teenagers, published this week in the Archives of Pediatric Medicine, found California teens to be consuming 158 fewer, daily calories than comparable high school students in other states. Keep in mind, that counts all the food eaten outside of school, indicating that California teens aren’t loading up on junk food after heading home.