Resting metabolic rate (RMR) is determined by approximately 80% by muscle mass, and each pound (450g) of additional muscle increases energy expenditure by 6 to 10 kcal per day.

noli's read

The claim that muscle is the primary driver of metabolism is widely supported by scientific literature, although the 80% figure is a significant simplification. In reality, resting metabolism is composed of several highly active organs (brain, liver, heart, kidneys) that consume more energy per unit of weight than skeletal muscle. Studies, such as those published in 'The American Journal of Clinical Nutrition', confirm that lean mass (which includes organs and muscles) is the best predictor of energy expenditure. The estimate of 6 to 10 kcal per pound of muscle is consistent with research data (notably the work of Forbes), which often suggests a value around 6-13 kcal per kg or pound depending on the models. While muscle plays a crucial role in long-term metabolic management, the idea that it 'explains' 80% of metabolism ignores the major portion linked to the basal metabolism of vital organs. It is a scientifically grounded analysis in its direction, but one whose statistical precision depends heavily on the individual's overall body composition.

the sources

1. 1Wu Y, Wang W, Liu T, Zhang D 2017
2. 2Li R, Xia J, Zhang X, et al. 2018