Your Basal Metabolic Rate (BMR) is the number of calories your body requires just to maintain basic physiological functions while at complete rest — breathing, circulation, cell production, protein synthesis, and temperature regulation. It represents the minimum energy your body needs to survive.
BMR typically accounts for 60–75% of your total daily energy expenditure (TDEE), making it by far the largest contributor to your daily calorie burn — more than exercise and digestion combined.
The Three BMR Formulas
1. Mifflin-St Jeor Equation (1990) — Recommended
Validated on a modern Western population, this is the most accurate for the general public according to the Academy of Nutrition and Dietetics:
⚠️ Metabolic Adaptation: Prolonged caloric restriction causes your body to lower BMR by 10–25% — a survival mechanism called "adaptive thermogenesis." This is why weight loss often slows after the first few weeks of dieting, even when maintaining the same caloric deficit.
How to Increase Your BMR
Build muscle mass: Resistance training is the most effective way to raise BMR long-term
Eat adequate protein: Protein has the highest thermic effect (20–30%) of any macronutrient
Avoid severe calorie restriction: Crash diets reduce BMR through adaptive thermogenesis
Stay hydrated: Even mild dehydration can reduce metabolic efficiency
Get adequate sleep: Sleep deprivation impairs hormones that regulate metabolism
Manage stress: Chronic stress elevates cortisol, which can disrupt metabolic hormones
❓ FAQ
BMR (Basal Metabolic Rate) is the calories burned at complete rest — just to sustain life functions. TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through physical activity, digestion (thermic effect of food), and non-exercise activity thermogenesis (NEAT). TDEE is the number you actually need to match for weight maintenance.
Eating below your BMR for extended periods is not recommended without medical supervision. It can cause muscle loss, nutrient deficiencies, hormonal disruption, and metabolic slowdown. Very low calorie diets (VLCDs below 800 kcal) should only be used under clinical supervision as part of a structured medical program.
Yes. BMR generally decreases by approximately 1–2% per decade after age 20, primarily due to the natural loss of muscle mass (sarcopenia). This is why it becomes easier to gain weight with age even without eating more. Regular resistance training can largely offset this decline by maintaining muscle mass.
⚕️ Medical Disclaimer: BMR values are estimates. Never eat below your BMR without medical supervision. Consult a healthcare professional before starting any diet or fitness program.