Postprandial Effects of Macronutrient Composition Meals on the Metabolic Responses and Arterial Stiffness Indices of Lean and Obese Male Adults: A Protocol of pilot Study

Abstract Background & Objective: Prior studies have shown that meal composition may affect the metabolic responses and arterial stiffness indices. Due to the lack of a comprehensive study that concurrently compares metabolic responses and vascular stiffness indices after receiving three different meals in lean and obese men, this pilot study has been conducted with a three-phase parallel design, aiming to investigate the effects of meal composition on the metabolic parameters and arterial stiffness indices of lean and obese adults. Materials and Methods: This pilot, parallel clinical trial has been performed on 20 male adults aged 18-35 years who are disease-free and selected based on the inclusion and exclusion criteria at Mashhad University of Medical Sciences, Iran. The subjects have completed three interventions at a one-week interval, including high carbohydrate (70% carbohydrates, 10% protein, 20% fat), high protein (30% protein, 50% carbohydrates, 20% fat), and high fat meal (50% fat, 40% carbohydrates, 10% protein). Postprandial effects have been assessed within 360 minutes after each meal, including the energy expenditure component (resting energy expenditure, thermic effects of feeding, respiratory quotient, and substrate oxidation) and arterial stiffness indices (augmentation index and pulse wave velocity). In addition, blood sampling has been performed to measure glucose, insulin, free fatty acids, and lipid profile. Results: The study has started since September 2020 and will continue until January 2021. The assessment of the intervention outcomes will be carried out six hours after the end of the intervention. Conclusion: The differences in the postprandial responses c affect the metabolic and vascular parameters due to different meal compositions, thereby providing beneficial data for the establishment of new strategies in terms of nutritional education and metabolic/vascular improvement.