Understanding Calories, BMR & Energy Expenditure

Your body requires energy (measured in kilocalories or calories) to perform vital biological functions like respiration, blood circulation, cellular repair, and daily physical activity. Understanding the difference between BMR (Basal Metabolic Rate) and TDEE (Total Daily Energy Expenditure) is essential for sustainable health and weight management.

Core Metabolic Equations

  • Mifflin-St Jeor (Men): BMR = (10 ร— W) + (6.25 ร— H) - (5 ร— Age) + 5
  • Mifflin-St Jeor (Women): BMR = (10 ร— W) + (6.25 ร— H) - (5 ร— Age) - 161
  • ICMR-NIN 2020 (Men 18โ€“30): BMR = 14.5 ร— W + 645
  • ICMR-NIN 2020 (Women 18โ€“30): BMR = 14.0 ร— W + 471
  • TDEE: TDEE = BMR ร— Activity Multiplier (1.2 to 1.9)

Frequently Asked Questions

What is the ICMR-NIN 2020 RDA standard?

The Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) establish dietary standards tailored to Indian body morphology. A Reference Indian Man weighs 65 kg (sedentary energy: 2,110 kcal) and Reference Woman weighs 55 kg (sedentary energy: 1,660 kcal).

Why do South Asians have different BMI cutoffs?

South Asians experience higher rates of insulin resistance, diabetes, and cardiovascular risk at lower BMIs due to higher body fat percentages and lower muscle mass ("thin-fat" phenotype). The WHO and Indian Health Ministry designate overweight at BMI โ‰ฅ 23 and obesity at BMI โ‰ฅ 25.

What is a safe calorie deficit for fat loss?

A moderate deficit of 300 to 500 kcal below TDEE allows for losing approximately 0.25 to 0.5 kg (0.5 to 1 lb) per week safely without excessive hunger, muscle wasting, or metabolic adaptation.

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