The first step to scientific weight loss: How to calculate your daily dietary calorie needs?

Dietary Energy Requirements and Distribution:

Dietary weight loss addresses the question of what and how much to eat, which means solving the problem of dietary energy requirements and food distribution. To solve this, it's necessary to know how to calculate dietary energy.

I. Calculation of Dietary Energy Requirements

(I) Units of Energy and Conversion
Joules (J), kilojoules (kJ), and megajoules (MJ) are commonly used internationally standardized units of energy. Some people conventionally prefer to use calories (cal) and kilocalories (kcal) as units of energy.

One joule (J) is equivalent to the energy required to move a 1kg object 1m with a force of 1 Newton.

One calorie (calorie) is the amount of heat required to raise the temperature of 1 milliliter (ml) of water from 15°C to 16°C.

1MJ=1000kJ

1kJ=1000J

1kcal=1000cal

1kcal=4.1868kJ

1kJ=0.239kcal

1MJ=239kcal

(II) Calculation of Human Energy Requirements

1. Calculation of Energy Required for Basal Metabolism

(1) Simple Estimation
Male:
Basal metabolic energy required = weight (kg) × 11 (kcal)
Female:
Basal metabolic energy required = weight (kg) × 10 (kcal)

(2) Complete Calculation
Male:
18～30 years old Basal metabolic energy required = 15.3 × weight (kg) + 679 (kcal)
30～60 years old Basal metabolic energy required = 11.6 × weight (kg) + 879 (kcal)
Over 60 years old Basal metabolic energy required = 13.5 × weight (kg) + 479 (kcal)
Female Basal metabolic rate (BMR) for individuals aged 18-30: 14.7 × body weight (kg) + 496 (kcal)
Basal metabolic rate (BMR) for individuals aged 30-60: 8.70 × body weight (kg) + 829 (kcal)
Basal metabolic rate (BMR) for individuals aged 60 and above: 10.5 × body weight (kg) + 596 (kcal)