Minnesota was one of just four states to post a drop in adult obesity rates last year, according to a new report that hints that the nation may finally be turning the tide on what has become a leading public-health threat.

Minnesota ranked 13th nationally in 2015 for low obesity rates, behind traditionally young and affluent states such as Colorado, California and Hawaii. Its adult obesity rate was 26.1 percent, compared with a national average of nearly 38 percent. Louisiana, Alabama and Mississippi had the highest rates.

The study was released by the Robert Wood Johnson Foundation, with data analyzed by the Trust for America’s Health.

Tempering Minnesota’s good news is that its decline in 2015 came off a small spike in 2014. But the state’s overall obesity trend has flattened out in the past decade after roughly doubling between 1990 and 2003.

The researchers noted that fewer states posted obesity increases last year than at any time in the past decade. It’s an encouraging sign, given the strong links between weight gain and chronic, costly ailments such as diabetes and heart disease.