How calories are burned

Many individuals labor under a misconception of how calories are burned.  The importance of knowing how calories are burned is very significant in the fight to stay healthy and in shape. Expend more calories than you consume and there will be weight loss.  The body burns calories three ways; resting metabolic rate (RMR), energy expended with exertions either from exercise or daily activities, and the thermic effect of food.

Resting metabolic rate is the most important of the three.

1.  Resting metabolic rate accounts for 60-75% of daily calories burned.  This means you burn the most calories while at rest.  The faster your metabolic rate the more calories you burn.  People with a high percentage of lean body mass (fat free mass) burn more calories while at rest.  This means it is important to not only lose fat but to gain muscle in the process.  It is also important to eat enough calories during the day.  Restricting calories will lower your Metabolism rate; this is why it is important to have a good healthy diet plan.

2.  Energy expended with exercise or daily activities account for 20-30% of your daily caloric output.   You can determine the amount of calories you burn according to your workout and intensity.  A typical exercise session will burn about 300 calories.   It is important to do some type of exercising because daily activities alone may not burn enough calories.

3.  Thermic effect of food accounts for about 10% of calorie expenditure.  If you eat a 400-calorie meal, about 40 calories are used for digestion and absorption.  This is another reason it is important to eat enough calories throughout the day.  10% of your calories burned actually come from eating.

Determining the Amount of Calories your body burns while at rest.

HARRIS BENEDICT EQUATION

The Harris Benedict Equation is a formula that uses your BMR (calories burned while resting) and then applies an activity factor to determine your total daily energy expenditure (calories).  The only factor omitted by the Harris Benedict Equation is lean body mass. Remember, leaner bodies need more calories than less lean ones.  Therefore, this equation will be very accurate in all but the very muscular (will under-estimate calorie needs) and the very obese (will over-estimate calorie needs).

STEP 1

Plug in the appropriate numbers and solve the formula above to find your BMR (Basal Metabolic Rate)

STEP 2

After you determine the BMR (Basal Metabolic Rate) choose the appropriate category from the chart.

STEP 3

After you choose the appropriate category, multiply your BMR times the proper number.  The answer will give you an estimate of your calories burned at rest.

EXAMPLE 1   

DETERMINE THE RESTING METABOLISM (AMOUNT OF CALORIES BURNED DURING REST) FOR SUSAN

Susan is 45 years old; she weighs 245 pounds and is 5 foot 5 inches tall.  She works the type of job where she sits for most of the day.  Susan does not exercise ever.  How many calories is Susan burning while at rest?

STEP 1  

·        First, find Susan’s BMR

·        Plug Susan’s weight, height, and age into the formula

BMR=655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in   years).

BMR=655 + (4.35 x 245)  + (4.7 x 65) – (4.7 x 45)

BMR=655 + 1065.75 + 305.5 – 211.5

BMR= 1814.75 

STEP 2

Determine where Susan falls on the figure 1.

            Since Susan sits at her desk most of the day and does not exercise she would fall   under the number 1.

Figure  SEQ Figure \* ARABIC 1

STEP 3

Plug numbers into the formula

The formula for number 1 is BMR X 1.2 

Plug in the appropriate numbers

SUSAN’S CALORIES BURNED WHILE AT REST = SUSAN’S BMR X 1.2

SUSAN’S CALORIES BURNED WHILE AT REST = 1814.75 x 1.2 = 2177.7

ANSWER:   SUSAN BURNS approximately 2177.7 CALORIES A DAY AT REST.

2177.7 are the amount of Calories Susan burns at rest. 

If Susan decided to exercise and burn 600 calories how many TOTAL calories would she burn?

FORMULA FOR SUSAN’S TOTAL CALORIES BURNED

SUSAN’S CALORIES BURNED RESTING + AMOUNT OF CALORIES BURNED EXERCISING.

Susan burns 2177.7 calories resting. If she burns an additional 600 calories exercising Susan would burn 2177.7+600=2877.7

SUSAN’S TOTAL CALORIES BURNED ARE 2877.7

If Susan wants to lose weight for that day she would have to eat less than 2877.7 calories.

Calories Burned needed to lose weight

There are approximately 3500 calories in a pound of stored body fat.  If you create a 3500-calorie deficit through a combination of diet and exercise, you will lose one pound of body weight. (On average 75% of this is fat, 25% lean tissue) If you create a 7000-calorie deficit, you will lose two pounds and so on.  The calorie deficit can be achieved either by calorie-restriction alone, or by a combination of fewer calories in (diet) and more calories out (exercise).  The combination of diet and exercise is the best method for lasting weight loss.  Sustained weight loss is difficult or impossible without increased regular exercise.