Your Basal Metabolic Rate is the calories your body burns just to keep you alive at rest. It's the foundation under every nutrition target. Standard formulas were built on Western bodies — toggle the Indian adjustment for a number that reflects how South Asian metabolism actually works.
Enter sex, age, weight and height. Your BMR updates as you change values.
Indian-adjusted estimate
BMR uses the Mifflin-St Jeor equation (1990), the formula recommended by the Academy of Nutrition and Dietetics as the most accurate predictive equation for healthy adults — outperforming the older Harris-Benedict formula, which overestimates by roughly 5%.
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + (5 if male, −161 if female)
The number tells you how many calories you'd burn in 24 hours lying perfectly still — keeping your heart pumping, brain firing, lungs breathing, kidneys filtering, and cells repairing. That's roughly 60-70% of your total daily energy use. Everything else — walking, talking, working, exercising — is added on top.
The Mifflin-St Jeor equation was validated on Western populations. Published research has since shown that South Asians have 5-11% lower BMR at matched height, weight, age and sex (Wouters-Adriaens & Westerterp, American Journal of Clinical Nutrition, 2008; Soares et al., European Journal of Clinical Nutrition, 1993).
The reason is the same thin-fat phenotype that drives metabolic disease risk in Indians — at any given body weight, South Asians carry more visceral fat and less lean muscle than Europeans. Muscle is metabolically active tissue; fat is not. Less muscle means a lower resting burn.
The 7% downward adjustment in Kaivo's "Indian-adjusted" mode sits in the middle of the published 5-11% range. If you want the un-adjusted Western default, toggle "Standard."
Think of it in financial terms. BMR is your fixed costs — the calories your body spends just to keep the lights on, whether you go to the gym or sleep all day. Activity is your variable costs. Add them together and you get TDEE — your total daily energy expenditure.
BMR is your engine at idle. TDEE is your engine actually running. It's BMR plus everything else your body does in 24 hours: walking to your car, typing emails, climbing stairs, the gym session, even fidgeting.
For planning a real-world calorie target, you need TDEE, not BMR. The standard way to estimate TDEE is to multiply BMR by an activity factor:
For a complete plan — TDEE, calorie target based on your goal, and a daily macro split — use our TDEE & Macros calculator. It builds on the BMR you've just calculated.
Don't eat your BMR. That's a common mistake. BMR is what you'd burn if you stayed in bed all day. Real-world calorie targets work off TDEE, with a modest (20-25%) deficit if your goal is weight loss.
BMR isn't fixed for life. It shifts with body composition, age, and physiological state. The big drivers:
Lean muscle burns roughly 3 times more calories at rest than fat tissue. Every 5 kg of muscle adds approximately 100 calories per day to BMR. This is why resistance training matters during any weight loss programme — and especially during GLP-1 therapy, where unsupervised users can lose 30-40% of their weight from muscle, dragging BMR down with it.
BMR drops roughly 2-3% per decade after 30, mostly because muscle mass declines (sarcopenia) and hormonal output (thyroid, growth hormone, testosterone) shifts. The Mifflin-St Jeor formula captures this with the −5 × age term.
Men have higher BMR than women at the same weight and height because they carry more lean mass and less fat on average. The formula reflects this with the +5 (male) / −161 (female) constants.
Hypothyroidism, PCOS, Cushing's, and some medications can lower BMR by 10-20%. Hyperthyroidism and stimulants raise it. If your measured weight loss is dramatically slower than your calculated TDEE predicts, a metabolic workup is worth doing — Kaivo's 35-marker panel includes thyroid and key hormones.
Crash diets trigger "adaptive thermogenesis" — your body suppresses BMR by 10-15% to defend against perceived starvation. This is one reason aggressive deficits backfire, and one reason the GLP-1 + structured nutrition combination outperforms diet alone.
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