This paper examines the effects of food prices on clinical measures of obesity, including body mass index (BMI) and percentage body fat (PBF) measures derived from bioelectrical impedance analysis (BIA) and dual energy x-ray absorptiometry (DXA), among youths ages 12 to 18. Using three waves of National Health and Nutrition Examination Survey (NHANES) data (1999-2000, 2001-2002, and 2003-2004) merged with several food prices measured by county and year, researchers found that increases in the real price of one calorie of food for home consumption and the real price of fast food result in significant reductions in the PBF among youths. They also found that an increase in the real price of fruits and vegetables has negative consequences for body composition outcomes. The results of the study indicate that measures of PBF derived from BIA and DXA are no less sensitive, and in some cases more sensitive, to fast food and fruits and vegetables prices than BMI.