The Effect of Intermittent Fasting on Resting Metabolism

Purpose: The aim of this study was to identify the effects of intermittent fasting (IF) on resting metabolic rate (RMR) and respiratory exchange ratio (RER). Intermittent fasting restricts the time interval in which calories are consumed without restricting the total number of calories. Methods: The study was conducted over two weeks. During the control week, participants consumed their normal diet ad libitum. In the experimental week, participants consumed a eucaloric diet but were restricted to an eight-hour feeding interval. Fasting RMR, RER, blood glucose, body composition, and cholesterol levels were measured. Data were collected at the end of each week. Results: During fasting, the average feeding interval was 6.79 hours (5.5 - 7.8 hrs). There were no significant differences between total calories consumed or macronutrient distribution. A significant decrease in RMR was found (2440.8 kcals, 1674.2 kcals, p = 0.04). There were no significant differences between other measures. Conclusion: Previous studies on IF are inconclusive and have either not tested RMR, showed no significant difference, or found a decrease in RMR. The direct effect on metabolic rate and clinical measures related to IF have not been determined. The effect of IF on metabolism requires further research