When it comes to nutrition policy, we know about a lot of things that don’t work: Soda taxes and proximity 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)

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.

“Unequivocally, California students in this study reported less at-school intake of fat, sugar, and total calories — the nutritional measures that California laws were designed to regulate — compared with other states in our sample, the report concludes. California may see stronger results than other studies of school nutrition regulation because, as the authors point out, its restrictions are the strictest in the nation.

To be sure, there’s also evidence on the other side of this issue: Other research has found junk food bans, for example, not to correlate with better nutritional outcome, mostly because of what kids eat at home (or, sometimes, what they sneak into school).

A 158 calorie-consumption reduction, however, will likely warrant significant attention in the public health community. That’s a huge change in eating habits and one that could make a significant dent in obesity rates. Researchers have previously estimated that, if children ate just 64 fewer calories each day, the obesity rate would fall 10 percent lower than where it stood in the mid-2000s.