Spurred by the growing crisis in child obesity, the nation’s schools have made “considerable improvements” in nutrition, fitness and health over the last six years, according to a new government survey that found that more schools require physical education and fewer sell French fries.

The survey, which is conducted every six years, shows that more schools than six years ago offer salads and vegetables and that fewer permit bake sales. More states and school districts insist that elementary schools schedule recess and that physical education teachers have at least undergraduate training. More states have enacted policies to prohibit smoking at school and to require courses on pregnancy prevention.

Perhaps most striking, 30 percent of school districts have banned junk food from school vending machines, up from 4 percent in 2000. Schools offering fried potatoes in their cafeterias declined, to 19 percent from 40 percent.

The results of the survey by the Centers for Disease Control and Prevention elicited cheers on Friday from public health and education officials, as well as warnings against complacency.