Body Mass Index
Your BMI is an indirect measure of your body composition — or how much body fat you have. Although BMI doesn’t measure body fat directly, it uses your weight and height to determine whether you’re classified as underweight, normal weight, overweight or obese.
Basal Metabolic Rate
Your BMR is the number of calories your body burns at rest to do basic functions like breathing, digesting, keeping your heart beating and all the other physiological tasks that keep you alive. Your BMR is partly determined by genetics, but other factors, like your body composition and activity level, may also have an effect on your BMR.
How BMI and BMR are Connected ?
Several factors affect your basal metabolic rate — and body fat composition is one of them. Those with more muscle mass tend to burn more calories at rest because muscle tissue requires more calories to maintain than fat tissue. Although BMI and BMR are not directly related, if you have a high BMI because of a high body fat percentage, your BMR may be lower. If you have a high BMI because of a large amount of muscle mass, your BMR may be increased. Additionally, if you are overweight, but very active, that doesn’t mean you’ll necessarily have a low BMR.