Figure 3. The daily energy and nutrient balance in relationship to macronutrient intake, and oxidation for a 30-year-old female that is 90-kg and 165 cm tall with 35% body fat on a 2,400 kcal/day standard American diet (35% fat, 50% carbohydrate, 15% protein) (48). Energy stores were calculated using the energy coefficient for fat free mass (1.1 kcal/g) and fat mass (9.3 kcal/g) (49). Macronutrient intake and oxidation are based on individual energy requirements computed using the Dietary Reference Intake equations (17). Macronutrient percentage, equivalent to the USDA Dietary Guidelines for Americans (50), is shown on the left as absolute intake in kilocalories and on the right as a percentage of its respective nutrient store. Because carbohydrate and protein intake and oxidation rates are tightly regulated daily, any inherent differences between energy intake and energy expenditure therefore predominantly impact body fat stores. During chronic overfeeding (shown in red), the oxidation of carbohydrate and protein is increased to compensate for their increased intake and at the expense of fat intake and the increase in fat oxidation is not equally coupled with its intake. Thus, if sustained fat kilocalories are stored, fat stores expand, and body weight is gained. This figure was adapted with permission from Galgani & Ravussin (42).