Relationship between protein intake in each meal and physical activity level : Cross-sectional Study (Preprint)
BACKGROUND Protein intake plays an important role in the synthesis and maintenance of skeletal muscle in the prevention of health risks. It is also widely known that physical activity influences muscle function. However, no large-scale studies have examined the relationship between daily dietary habits, especially the timing of protein intake, and daily physical activity. OBJECTIVE The purpose of this study was to investigate the relationship between protein intake and composition during the three meals and the amount of daily physical activity using a cross-sectional study design. METHODS Using the daily dietary data accumulated in the phone food-log application “Asken” and a web-based cross-sectional survey to the Asken users (total N = 8,458), we analyzed the nutrient intake and daily activity levels. RESULTS Correlation analysis revealed that breakfast and lunch protein intake had higher positive correlations with daily physical activity among the three major macronutrients (protein, fat, and carbohydrate). These findings were confirmed by multiple regression analysis with confounding factors. Also, participants with higher protein intake and composition at breakfast or lunch tended to exhibit significantly greater physical activity than those with the higher protein intake at dinner. CONCLUSIONS Among the three macronutrients, protein intake during breakfast and lunch was closely associated with daily physical activity.