Basal Metabolic Rate, Harris Benedict Equation & Fitness calories burned

Monday, January 23, 2012

I am fascinated with the Basal Metabolic Rate & Harris Benedict Equation. I mean, really, wouldn’t it be interesting if we could boil weight loss down to a mathematical equation? The BMR and HBE attempt to do that. I add to these formulas a little 'calories burned in fitness' chart in my Healthometer Official Calorie Counter book.

First, calculate your BMR using the online calculator or manual formula. The result is how many calories your body needs to function in a day, if you slept all day.

Basal Metabolic Rate online calculator

BMR Manual Formula
Women: BMR = 655 + ( 4.35 x weight#) + ( 4.7 x height in " ) - ( 4.7 x age in yrs )
Men: BMR = 66 + ( 6.23 x weight# ) + ( 12.7 x height in " ) - ( 6.8 x age in yrs )

Then adjust by the Harris Benedict Equation. This equation adds to the BMR calories based on your base activity level, before fitness when you are awake.

Harris Benedict Formula
To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:

If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

Next, estimate your calories burned per hour of extra activity:

Light Activity: 100-160 calories burned per hour
Cleaning house
Office work
Playing baseball
Playing golf

Moderate Activity: 170-340 calories burned per hour
Walking briskly (3.5 mph)
Cycling (5.5 mph)
Playing basketball

Vigorous Activity: 350-700 calories burned per hour
Jogging (9 min/mile)
Playing football

Very Strenuous Activity:700 or more calories burned per hour
Running (7 min/mile)

Putting it all together...............

My BMR calculates out to 1288 calories a day if I slept all day
Adjusting with the Harris Benedict Equation, I will multiply by 1.2 [sedentary lifestyle] equaling 1545 calories/day just to get through the day without fitness.
I then calculate my calories burned with physical fitness using the chart above.

I like to put it all together using weekly numbers.

Using my Harris Benedict Equasion of 1545 x 7 =10815 calories a week
Consumed 1300 calories a day x 7 = 9100 calories a week, resulting in a 1715 calorie deficit

Added to my exercise est 300 minutes/week=5 hrs x 500 avg cal= 2500 calories/week
I will have a calorie deficit of 1715 consumed + 2500 burned in fitness=4215 calorie deficit.

Since 3500 calories = 1 pound, this should result in a weight loss of 1.2 pounds this week.

Let's see it my formula works at my next weigh in!
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