If you’ve ever thought about your weight in relation to your overall health (who hasn’t?), you’ve likely wondered how metabolism plays a part in the equation—or what metabolism even is.
Metabolism is the complex biochemical process that makes energy your cells need to function and keep your body healthy. “Metabolism isn’t just about weight. It actually has more to do with how our body uses the food we eat and converts it to fuel for energy,” shares Scheller.
In medical terminology, metabolism is measured as basal metabolic rate (BMR). Essentially, your BMR is the amount of energy your body needs to carry out essential functions (e.g., breathing, blood circulation, hormone regulation) even when it’s resting. In other words, the higher your BMR, the faster your metabolism.
The aspect that influences BMR the most is your lean body mass (aka lean muscle mass), which is the weight of everything except body fat (i.e., muscle, body water, organs, skin, bones). The higher your lean body mass, the more energy your body requires at rest (and the higher your BMR).
Because fat is not as metabolically active as lean muscle mass, the alternative is also true—if a body composition has a higher fat percentage, it requires less energy. As a result, individuals with a lower lean muscle mass have a lower BMR and a slower metabolism.
As you can see, improving your metabolic rate and increasing your metabolism is the key to losing fat and gaining muscle (and it’s definitely not as simple as “calories in, calories out”).