Students in states such as Connecticut and West Virginia have limited access to junk food like candy and chocolate on school grounds while those in Louisiana and Idaho can buy it in abundance, according to an analysis by the Pew Charitable Trusts and the Robert Wood Johnson Foundation.

U.S. childhood and adolescent obesity rates have more than tripled in the past 30 years. Schools, where kids consume most of the day's calories, are seen as a logical place to try reversing the trend.

The groups analyzed 2010 data from the Centers for Disease Control and Prevention. That showed a hodgepodge of state policies that researchers said shows the need for tighter standards over what snacks are sold in schools.

"Under this patchwork of policies, the majority of our nation's children live in states where less-healthy snack food choices are readily available," researchers wrote in their report, part of the groups' joint Kids' Safe and Healthful Foods Project.

"In nearly three-quarters of the states, a substantial percentage of schools sell low-nutrient, high-calorie snacks such as chocolate, other candy, or full-fat salty chips."

Most middle schools and high schools, attended by children aged about 11 to 17, also do not sell fruits and vegetables outside traditional cafeteria lunch lines so that students can find them at random times, the report showed.

While many states technically have policies covering snack food, what kinds of foods they allow is at issue, it said.

Congress in 2010 called for rules on minimum health standards for snacks sold in schools but the U.S. Department of Agriculture is nearly a year behind in proposing such standards.

USDA officials have said they need more time to make sure the regulation is done right, a delay that has drawn criticism from nutrition advocates and others.

"The bottom line is: it's clear that so many children are being served less healthy snack foods in their school, and that really is something we could do something about," said Erik Olson, director of Food Programs at Pew's health group.

Food and beverage companies generally backed the 2010 call for healthier school foods. Beverage makers, for example, have touted their voluntary efforts to pull full-calorie sodas from some schools.

Other studies have suggested that regulating school snack foods, also known as "competitive foods," can help children gain less weight but Thursday's findings show many schools have yet to take action.

The report lauded examples of "successful snacking," including in some cases major recent trends away from fatty, sugary foods:

• New Hampshire, where half of the state's schools sell fruit options in school stores, snack bars or vending machines;

• Michigan, where more than one-third of the schools sell vegetables in snack venues;

• Alabama, where just 11 percent of schools sold full-fat salty snacks in 2010, down from 45 percent in 2006.

• Rhode Island, where only 2 percent of schools sold non-chocolate candy in 2010, down from 29 percent in 2006.

• West Virginia, where in 2010 3 percent of schools sold soda or fruit drinks and 2 percent sold chocolate candy.

(Reporting by Susan Heavey; Editing by Ros Krasny and Bill Trott)

(This story is refiled to correct spelling of name to Olson in eleventh paragraph, not Olsen)

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