Before you can lose weight, build muscle, or maintain your current body — you need to know how many calories your body burns just to stay alive. That number is your BMR, and it is the foundation of every nutrition plan that actually works.
BMR stands for Basal Metabolic Rate — the number of calories your body burns at complete rest just to keep vital functions running: breathing, blood circulation, cell repair, temperature regulation, and organ function. Think of it as the fuel cost of simply existing.
Even if you lay in bed all day and did nothing, you would still burn your BMR calories. It typically accounts for 60–75% of your total daily calorie burn.
BMR is your resting calorie burn. TDEE (Total Daily Energy Expenditure) is your total calorie burn including all activity. To get your TDEE, you multiply your BMR by an activity multiplier:
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little/no exercise | BMR × 1.2 |
| Lightly Active | Light exercise 1–3 days/week | BMR × 1.375 |
| Moderately Active | Exercise 3–5 days/week | BMR × 1.55 |
| Very Active | Hard exercise 6–7 days/week | BMR × 1.725 |
| Extra Active | Physical job + hard training | BMR × 1.9 |
Your TDEE is the number of calories you need to maintain your current weight. Eat less → lose weight. Eat more → gain weight.
There are several BMR formulas, but the Mifflin-St Jeor equation is the most accurate for most people according to modern research:
35-year-old woman, 65 kg, 165 cm tall:
BMR = (10 × 65) + (6.25 × 165) − (5 × 35) − 161
= 650 + 1031.25 − 175 − 161 = 1,345 calories/day
If she has a moderately active lifestyle: TDEE = 1,345 × 1.55 = 2,085 calories/day to maintain her weight.
To lose weight, you need a calorie deficit — consuming less than your TDEE. The standard recommendation is a 500 calorie/day deficit, which leads to approximately 0.5 kg (1 lb) of fat loss per week.
| Goal | Daily Calories | Expected Result |
|---|---|---|
| Aggressive fat loss | TDEE − 750 | ~0.75 kg/week loss |
| Moderate fat loss | TDEE − 500 | ~0.5 kg/week loss |
| Gentle fat loss | TDEE − 250 | ~0.25 kg/week loss |
| Maintain weight | = TDEE | No change |
| Muscle gain | TDEE + 200–300 | Lean bulk |
Research suggests that South Asians may have a slightly different body composition compared to Western populations — higher body fat percentage at the same BMI. Some nutritionists recommend using a slightly lower BMI cutoff (23 instead of 25) for Indians when assessing health risk. However, the Mifflin-St Jeor BMR formula remains applicable — it is based on weight, height, and age, not ethnicity.
What does differ for many Indians is activity level. A largely sedentary IT professional sitting 8–10 hours daily has a very different TDEE than the formula's "moderately active" default assumes.
Yes. Your BMR represents the minimum calories your organs need to function. On rest days your TDEE will be lower (BMR × 1.2 if sedentary), but you should still eat at or above your BMR to protect muscle and organ function.
Common reasons: underestimating food portions, overestimating activity level (fitness trackers overcalculate burn by 20–30%), water retention masking fat loss on the scale, or metabolic adaptation after prolonged dieting. Recalculate your TDEE every 4–6 weeks as you lose weight, since a lighter body burns fewer calories.
The most effective way is to build more muscle mass through strength training. Each kg of muscle burns roughly 13 calories per day at rest — modest individually, but significant across a full body. Eating adequate protein (1.6–2.2g per kg of body weight) helps preserve muscle during weight loss.