WASHINGTON — High-calorie sports drinks and candy bars will be removed from school vending machines and cafeteria lines as soon as next year, replaced with diet drinks, granola bars and other healthier items.

The Agriculture Department said today that for the first time it will make sure that all foods sold in the nation’s 100,000 schools are healthier by expanding fat, calorie, sugar and sodium limits to almost everything sold during the school day.

That includes snacks sold around the school and foods on the “a la carte” line in cafeterias, which never have been regulated before. The new rules, proposed in February and made final this week, also would allow states to regulate student bake sales.

The rules, required under a child nutrition law passed by Congress in 2010, are part of the government’s effort to combat childhood obesity. The rules have the potential to transform what many children eat at school.

Current standards already regulate the nutritional content of free and low-cost school breakfasts and lunches that are subsidized by the federal government, but most lunchrooms also have the “a la carte” lines that sell other foods — often greasy foods like mozzarella sticks and nachos.

Under the rules, those lines could offer healthier pizzas, low-fat hamburgers, fruit cups or yogurt, among other foods that meet the standards.

One of the biggest changes under the rules will be a near-ban on high-calorie sports drinks, which many beverage companies added to school vending machines to replace high-calorie sodas that they pulled in response to criticism from the public health community.

The rule would only allow sales in high schools of sodas and sports drinks that contain 60 calories or less in a 12-ounce serving, banning the highest-calorie versions of those beverages.