Complete Guide to Understanding Your Metabolism

Your Basal Metabolic Rate (BMR) is the calories your body burns at rest to maintain basic functions like breathing, circulation, and cell production. BMR accounts for 60 to 75 percent of daily calorie burn. Total Daily Energy Expenditure (TDEE) adds activity calories on top. Use our metabolism calculator to find your personal BMR and TDEE based on your age, weight, height, and activity level.

Several factors influence your metabolism: muscle mass (muscle burns more calories than fat at rest), age (metabolism drops about 2 percent per decade after 20), sex (men typically have higher BMR due to more muscle mass), genetics, and thyroid function. While you cannot change your age or genetics, you can significantly impact your metabolism through exercise and body composition changes.

Each pound of muscle burns approximately 6 calories per day at rest versus 2 calories for fat. Resistance training 2 to 3 times per week can add 5 to 10 pounds of muscle over a year, increasing your resting metabolism by 30 to 60 calories daily. This compounds over time. Combine strength training with adequate protein intake of 0.7 to 1 gram per pound of body weight to maximize muscle growth.

Severe calorie restriction (below 1,200 calories) slows metabolism through adaptive thermogenesis. Instead, aim for a moderate deficit of 300 to 500 calories below your TDEE for sustainable weight loss of 0.5 to 1 pound per week. Eat sufficient protein with every meal — protein has the highest thermic effect of food, meaning your body burns 20 to 30 percent of protein calories during digestion compared to 5 to 10 percent for carbs.