to undercut nutrition standards, and notes that several Native American schools are working to improve the quality of school lunches by using produce from school gardens, or tribally grown buffalo meat. Current challenges Caloric and nutritional needs For some time, the measurement on which the NSLP based its cash-reimbursements and meal provisions largely came from caloric requirements. However, while this worked at a time when malnutrition plagued the nation's poor, a continuing focus on caloric intake ignores the growing national obesity epidemic. Balancing nutrition and calories has always been a challenge for the NSLP and its participating schools. This struggle can undermine schools that wish to comply with the national standards while still advocating healthy lifestyles. Another problem that contributes to this challenge is that nutritious food is often considered less favorable than competitive food that is available to students. Given the choice, students will often prefer competitive foods that are not required to meet federal minimum nutrition standards. Competitive foods In the US, the term competitive foods refers to any food source that competes with a lunch program's offerings. Such competitive foods include fast food offerings, a la carte food lines, and vending machines. A study was done in the 2009–2010 school year across 47 states and 622 districts to examine how much of the districts' competitive food and drink policy complied with Dietary Guidelines for Americans (DGA) recommendations. One of the major reasons for this study to be done is the Healthy, Hunger-Free Kids Act which requires schools to establish a science-based nutrition standards for competitive foods called a wellness plan. These provisions for competitive food and drinks included limits on specific nutrients in the food, such as sodium and fats. Less than 5% of districts met or exceeded DGA requirements. Only about 4% of districts across the nation required fruits and vegetables to be sold within the competitive foods which in no way helps the fruit and vegetable intake of students that is already sub-par. Food waste In a study of the Boston Public Schools, "on average, students discarded roughly 19 percent of their entrées, 47 percent of their fruit, 25 percent of their milk, and 73 percent of their vegetables." "It was estimated that $432,349.05 worth of food is wasted annually at lunch by students in Grades 6–8 in [Boston Public Schools]." Overall, this sum makes up 26.1 percent of these three schools' food budgets, excluding