Question 1

What is BMR?

Accepted Answer

BMR (Basal Metabolic Rate) is the number of calories your body needs to maintain basic physiological functions while completely at rest — breathing, circulation, cell production, and temperature regulation. It represents your minimum calorie requirement to stay alive. Most people's BMR accounts for 60–75% of total daily calorie expenditure.

Question 2

What is TDEE?

Accepted Answer

TDEE (Total Daily Energy Expenditure) is your total calorie burn over a day, including BMR plus all physical activity. It's calculated by multiplying your BMR by an activity factor. TDEE is the most useful number for setting calorie targets — eating at TDEE maintains your weight, below TDEE creates a deficit for weight loss, and above TDEE creates a surplus for muscle gain.

Question 3

Which formula is most accurate?

Accepted Answer

The Mifflin-St Jeor equation is the most widely validated for the general population and is recommended by the Academy of Nutrition and Dietetics. It tends to be more accurate than the original Harris-Benedict equation, which is known to slightly overestimate BMR. The Katch-McArdle formula is the most accurate for people who know their body fat percentage, as it uses lean body mass rather than total body weight — making it better for athletes and muscular individuals.

Question 4

Why does my BMR seem high or low?

Accepted Answer

BMR varies significantly with body size, age, and sex. A larger, heavier body has more tissue to maintain and therefore a higher BMR. BMR declines by roughly 1–2% per decade after age 20. Men generally have a higher BMR than women of the same weight because of higher muscle mass on average. These formulas provide estimates — actual BMR can vary by ±10% from the predicted value due to genetics, thyroid function, and other factors.

Question 5

Should I eat at my BMR to lose weight?

Accepted Answer

No — eating at BMR is not recommended for most people. BMR is the energy required for basic survival functions; eating only your BMR would mean your body has no calories for any activity, including walking to get food. Most evidence-based weight loss approaches suggest a deficit of 500–750 calories below TDEE, which produces approximately 0.5–0.75 kg of weight loss per week. Deficits below BMR are associated with muscle loss, nutrient deficiencies, and metabolic adaptation.

Formula	Best for	Inputs needed
Mifflin-St Jeor (1990)	Most people — best validated formula	Sex, age, height, weight
Harris-Benedict (1919)	Historical standard, slight overestimate	Sex, age, height, weight
Katch-McArdle (1975)	Athletes or those who know their body fat %	Lean body mass (from body fat %)

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