Josh Massingham says…
Energy expenditure at rest is highly variable, independent of body size or composition and is referred to as your “metabolic rate”. Research has established that people with a low metabolic rate have an increased risk of developing obesity-related disease than those with a high metabolic rate. Further studies have investigated the impact of skeletal muscle mass on our metabolic rate and suggests that a greater amount of muscle mass may increase your energy expenditure at rest. It is important to note that this only accounts for a small portion of the wide variance in metabolic rate observed between people as other factors such as thyroid hormone, muscle fibre types, neural innervation, and many more play an important role in our metabolic rate.