Question 1

What is the difference between BMR and TDEE?

Accepted Answer

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep your organs functioning, your heart beating, and your lungs breathing. TDEE (Total Daily Energy Expenditure) adds the calories burned through daily activity and exercise on top of BMR. For most people, BMR accounts for 60-75% of total daily calorie burn. TDEE is the number you actually need to match with food intake to maintain your current weight.

Question 2

Which BMR formula is most accurate?

Accepted Answer

The Mifflin-St Jeor equation, published in 1990, is considered the most accurate BMR formula for most adults and is recommended by the Academy of Nutrition and Dietetics. It was validated against indirect calorimetry (the gold standard) and outperformed the older Harris-Benedict equation. However, no formula is perfectly accurate for every individual — actual BMR can vary by 5-10% due to genetics, body composition, and hormonal factors.

Question 3

How do I choose the right activity level?

Accepted Answer

Sedentary (1.2x) means desk work with no intentional exercise. Lightly Active (1.375x) means 1-3 days of light exercise per week. Moderately Active (1.55x) is 3-5 days of moderate exercise. Active (1.725x) is hard exercise 6-7 days per week. Very Active (1.9x) is intense daily training or a physically demanding job plus exercise. When in doubt, choose one level lower than you think — people tend to overestimate their activity level.

Question 4

Does BMR change with age?

Accepted Answer

Yes, BMR decreases by approximately 1-2% per decade after age 20, primarily due to loss of lean muscle mass (sarcopenia). A 50-year-old typically has a BMR roughly 200-300 calories lower than a 20-year-old of the same weight and height. Strength training can slow this decline by preserving and building muscle mass, which is metabolically more active than fat tissue.

Question 5

Can I increase my BMR?

Accepted Answer

The most effective way to increase BMR is to build lean muscle mass through resistance training — each kilogram of muscle burns roughly 13 calories per day at rest, compared to about 4.5 calories for a kilogram of fat. Other factors that temporarily boost metabolic rate include high-protein meals (thermic effect of food), cold exposure, and caffeine. Crash diets and severe calorie restriction actually lower BMR, a phenomenon called metabolic adaptation.

Question 6

Why is my TDEE important for weight loss?

Accepted Answer

TDEE tells you exactly how many calories you burn each day. To lose weight, you need to eat fewer calories than your TDEE — a 500-calorie daily deficit leads to approximately 0.5 kg (1 lb) of fat loss per week. Eating below your BMR is generally not recommended as it can trigger metabolic slowdown, muscle loss, and nutrient deficiencies. A deficit of 15-25% below your TDEE is considered safe and sustainable for most people.

Question 7

How accurate is the TDEE calculation?

Accepted Answer

TDEE calculations based on BMR formulas and activity multipliers are estimates with a typical margin of error of 10-15%. Individual variations in genetics, non-exercise activity thermogenesis (NEAT), hormonal status, and gut microbiome all affect actual energy expenditure. Use the calculated TDEE as a starting point, then adjust based on real-world results — if your weight is stable over 2-3 weeks, your calorie intake matches your true TDEE.

BMR & TDEE Calculator — Find Your Daily Calorie Expenditure