Harris benedict equation

General
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harris benedict equation

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What is the Harris-Benedict Equation?

The Harris-Benedict Equation is a formula used to estimate an individual’s Basal Metabolic Rate (BMR) and daily calorie requirements. BMR represents the number of calories your body needs to maintain basic physiological functions such as breathing, circulation, and cell production at rest. The equation takes into account factors such as age, sex, weight, and height to provide a personalized estimate of calorie needs.

Harris-Benedict Equation Formulas

There are two versions of the Harris-Benedict Equation: the original version from 1919 and a revised version from 1984. The revised version is generally preferred due to its increased accuracy.

Original Harris-Benedict Equation (1919)

For Men:

BMR = 66.5 + (13.75 \times \text{weight in kg}) + (5.003 \times \text{height in cm}) - (6.75 \times \text{age in years})

For Women:

BMR = 655.1 + (9.563 \times \text{weight in kg}) + (1.850 \times \text{height in cm}) - (4.676 \times \text{age in years})

Revised Harris-Benedict Equation (1984)

For Men:

BMR = 88.362 + (13.397 \times \text{weight in kg}) + (4.799 \times \text{height in cm}) - (5.677 \times \text{age in years})

For Women:

BMR = 447.593 + (9.247 \times \text{weight in kg}) + (3.098 \times \text{height in cm}) - (4.330 \times \text{age in years})

Using the Harris-Benedict Equation to Estimate Daily Caloric Needs

To estimate daily caloric needs, you need to multiply the BMR by an activity factor that corresponds to your level of physical activity. The activity factors are as follows:

  • Sedentary (little or no exercise): BMR x 1.2
  • Lightly active (light exercise/sports 1-3 days/week): BMR x 1.375
  • Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55
  • Very active (hard exercise/sports 6-7 days a week): BMR x1.725
  • Super active (very hard exercise/physical job & exercise 2x/day): BMR x 1.9

Example Calculation

Let’s calculate the daily caloric needs for a 30-year-old woman who weighs 70 kg, is 165 cm tall, and is moderately active.

  1. Calculate BMR using the Revised Harris-Benedict Equation (1984):
BMR = 447.593 + (9.247 \times 70) + (3.098 \times 165) - (4.330 \times 30)
BMR = 447.593 + 647.29 + 511.17 - 129.9
BMR = 1476.153 \, \text{calories/day}
  1. Determine daily caloric needs by multiplying BMR by the activity factor for moderately active:
\text{Daily Caloric Needs} = BMR \times 1.55
\text{Daily Caloric Needs} = 1476.153 \times 1.55
\text{Daily Caloric Needs} \approx 2287 \, \text{calories/day}

Conclusion

The Harris-Benedict Equation is a useful tool for estimating your BMR and daily caloric needs based on your personal attributes and activity level. By understanding your calorie requirements, you can make more informed decisions about your diet and exercise routines to achieve your health and fitness goals.