Figure 1.

Study time line. Subjects followed a 3-day standardized low-carbohydrate diet composed of 15% carbohydrate, 25% protein, and 60% fat. Individual dietary requirements were determined by a registered dietitian and calculated using the Harris Benedict equation. On the fourth day, after an overnight fast, a 10-h stable isotopically labeled OGTT was performed, and blood and breath samples were collected every 30 min.