The U.S. Department of Agriculture announced Thursday new rules that require schools to get rid of unhealthy snacks and eliminate students' exposure to junk food.

They include improving the nutritional quality of all food in schools, rapid growth of farm-to-school efforts to more than 42,000 participating schools and implementing national professional standards for all school nutrition employees who manage and operate the school meal programs.

According to prepared remarks, the USDA will assist schools by implementing mentor-based training for school nutrition professionals through the Team Up for School Nutrition Success initiative.

The new rules are part of the Healthy, Hunger-Free Kids Act where more than 52 million children now have healthier school environments than ever before with over 98 percent of schools meeting the healthier meal standards.

Dr. Rosa Cataldo, who runs Stony Brook Children's Healthy Weight and Wellness Center, says the guidelines mean snacks must be packed with more whole grains, less sugar and fewer calories.

"Sticking to no-calorie beverages, flavored water, things like baked chips rather than candy," she says.

The guidelines are also part of first lady Michelle Obama's "Let's Move!" initiative started in 2010.