However, food manufacturers are already taking steps in the right direction by reducing pack sizes, addressing concerns that products sold in vending machines encourage students to consume more calories.
Beverages in vending machines were found to have added sugars, high-calorie 100 percent fruit juices and snacks over 200 hundred calories, according to the figures from the HEALTHY Study which is a nationwide effort led by Temple University to curb obesity and type 2 diabetes in middle school students
It said that despite efforts to include more healthy choices at schools, standard offerings from vending machines, including fruit juices, are giving students more calories than they require.
Amy Virus, senior health services coordinator for the study from the Center for Obesity Research and Education at Temple University, said: "Contrary to common belief, fruit juice is not a healthy snack, if drunk in excess. It should be limited to about six ounces per day, but it's common to see more than one serving in a bottle.
"Changes made to the vending machines in schools will help reduce excess calories taken in by school kids."
Virus, who is also president of the Pennsylvania Dietetic Association, said: "The program's goal is to ultimately remove all juice and sugar added beverages, offer water instead and eliminate candy from vending machines."
Data from 42 schools across seven cities showed that 75 percent of had vending machines. Of those machines, 83 percent sold beverages alone and 17 percent sold snack foods only. The most prevalent beverages available in vending machines were added sugar beverages (39 percent) and 100 percent fruit juice (23 percent).
The most prevalent snacks available were reduced fat chips (22 percent), regular baked goods (16 percent), cereal bars (14 percent) and low fat ice cream (14 percent).
Overall, the energy content of beverages ranged from zero calories for water to 325 calories for added sugar drinks. For snacks it was between 25 calories for low fat ice cream, to 480 calories for baked goods.
There is increasing pressure on the food and drinks industry to stop marketing products of poor nutritional quality to children.
However, a report issued last month showed that the “beverage industry continues to significantly cut calories in schools” two years into the national School Beverage Guidelines scheme which was set up in 2006. This voluntary initiative is between the Alliance for a Healthier Generation, American Beverage Association (ABA), The Coca-Cola Company, Dr Pepper Snapple Group and PepsiCo.
The guidelines call for the beverage industry to provide lower-calorie and smaller-portion options in schools, including the removal of full-calorie soft drinks, all by the 2009-2010 school year.
The ABA’s School Beverage Guidelines Progress Report 2007-2008 showed that beverage calories shipped to schools have decreased by 58 percent since 2004 and 79 percent of schools under contract with bottlers are already in compliance with the national School Beverage Guidelines.
The association said the shift towards lower-calorie, smaller-portion beverages was contributing to the reduction in calories available from beverages in schools, as well as the change in the beverage mix available to students.
Vending machines are a major source of marketing through product sales and advertising on the machine’s exterior. Some states have strong nutrition standards for food sold in schools.
Yet, while schools are working to reduce junk-food sales, many vending machines are still stocked with soda, juice drinks, iced tea, candy, cookies and chips, according to the Center for Science in the Public Interest (CSPI).