<qa>  What is the OA diet designed to simulate?In order to address this hypothesis, we propose the following double-masked, randomized control trial. Indirect calorimetry will be performed in the fed and fasting state in young, healthy adults who will be studied under two conditions: after a 30-day, supervised, solid food diet and then again after a 30-day formula diet. The subjects will be randomized to receive either a Control Formula Diet of the same macronutrient and fatty acid composition as the solid food diet OAPA16.4 total kcal or a High Oleic Acid Formula Diet OA31.4 total kcal and PA1.7 total kcal. The Control Diets solid and liquid provide amounts per kcal of total fat, saturated fat, and OA that are similar to the to the 50-75th percentile of intake of young adult Americans but above the intake of total fat and saturated fat that is recommended for optimal long-term health. The High OA Formula Diet is designed to simulate the fat source of the Mediterranean Diet. The High OA diet will result in a 167 increase in the intakekcal of OA in the sn-1 and sn-3 positions of the dietary triacylglycerol. Using dual-energy x-ray absorptiometry DEXA, we will monitor body composition before and after each diet, while adjusting energy intake to maintain constant body weight. The following Specific Aims will be addressed: 