Given two isocaloric meals (600 kcal each): Meal A = 40 g protein, 50 g carbohydrate, 20 g fat, 10 g fiber; Meal B = 10 g protein, 70 g carbohydrate, 35 g fat, 2 g fiber. Which is expected to produce greater satiety and which mechanisms explain this?

• A. Meal B will be more satiating because higher fat content remains longer in the stomach and provides more immediate suppression of CCK and leptin, thus preventing subsequent hunger.
• B. Both meals will produce identical satiety responses since calorie content alone dictates fullness irrespective of macronutrient composition or gut peptide release.
• C. Meal A will reduce satiety compared with meal B because protein enhances ghrelin secretion leading to increased short-term hunger after the meal.
• D. Meal A should produce greater satiety due to higher protein (stimulates satiety hormones and increases diet-induced thermogenesis) and higher fiber (increases gastric volume and delays gastric emptying), reducing subsequent intake.

Answer: (D)