Class notes
BSC 2086 Metabolism Handout
- Course
- BSC 2086C
- Institution
- Florida State College At Jacksonville
This is a comprehensive and detailed handout on metabolism.
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Metabolism Lab:Metabolic rate is the overall rate at which metabolic reactions use energy. The basal metabolic rate (BMR) is
the amount of energy usage under fasting, restful conditions. Typically, BMR is determined by measuring the
amount of O2 consumption per kilocalorie of food metabolized. However, the measurement of O2 consumption
requires specialized equipment. We know that metabolic rate depends on the type of energy producing nutrient
that is being used and on the body surface area, age, and sex. Standardized tables, such as the one below have
been developed to estimate the average BMR based on age and gender.
Normal Standards of Basal Metabolic Rate
Age Cal/M2/Hr
Male Female
6 53 50.6
10 48.5 45.9
16 45 38.9
17-19 42.7 36.7
20-21 41.1 36.2
22-23 40.8 36
24-30 40 35.9
31-40 38.7 35.7
41-50 37.4 35
51-60 36.4 33.6
61-70 34.8 32.3
Additionally, we can estimate the average BMR based on the following formulas:
Basal Metabolic Rate Calculations
Age Equation
Males
3.9 22.7 x body wt (in kg) + 495
10.17 17.5 x body wt (in kg) + 651
18.29 15.3 x body wt (in kg) + 679
30.60 11.6 x body wt (in kg) + 879
> 60 13.5 x body wt (in kg) + 487
Females
3.9 22.5 x body wt (in kg) + 499
10.17 12.2 x body wt (in kg) + 746
18.29 14.7 x body wt (in kg) + 496
30.60 8.7 x body wt (in kg) + 829
> 60 10.5 x body wt (in kg) + 596
1
, A sample calculation based on a 154 lb male, age 20 would be:
154 lbs/2.2 = 70 kg
15.3 x 70 + 679 = 1750 kcal/day
EXERCISE 1: Calculation of average BMR and Daily Caloric Needs:
Calculate your estimated BMR using the above formula.
It is best to recognize that this is a table based on statistical analysis and that each individual will have
variations depending on their own body composition. If you have low thyroid hormone, your values would be
less than these predicted values, for example. Muscle requires more energy than fat to sustain, therefore a
person weighing 200 lbs. who is lean, and musculature will have a higher BMR than someone who weighs 200
lbs due to excess fat. Most people tend to look at these values within a range of plus or minus 10%, which takes
in much more of the population. To determine the range, find 10% of your predicted BMR. Now subtract that
number from the BMR to get one side of the range and then add it to BMR to get the high side of the range.
1. Your calculated BMR___1672kcal/day__ Your range of BMR _ 1507.8 to 1839.2 kcal/day__________
Of course, this is based on resting values. A basically sedentary person (a typist) would add 15% increase to
their BMR to determine the amount of caloric intake they need per day. Light activities (like a teacher) add 25-
30% to your basic nutrient requirements. Moderate activity (like a nurse) adds 30-45% and heavy work (like a
laborer) adds 75 to 85% to your daily energy requirement. Remember, these are approximations, and may not
truly capture your individual energy requirements.
Determine the percentage category your activity level places you in. Determine that percent of your BMR and
add it to your BMR. For example, if our 154 lb male laborer above had a BMR of 1750 Kcal./day, 75% of that
would be 1,312.5 kcal day.
1750kcal/day x .75 (75%) = 1,312.5 kcal/day
Which would mean he would need to ingest:
1750 (BMR) + 1,312.5 (additional) = 3,062.5 kcals/day to maintain his body weight. We could again use our
10% figure to determine his range by adding and subtracting 306 to and from 3,062.5 such that
3062.5 + 306 = 3368.5
3062.5-306=2,756.5
Making his daily intake range between 2,756.5 and 3,368.5.
Once again, his body composition and specific things can push him to the top or bottom of the range, depending
on his particular circumstances. Since he is a roofer and tends to work in the hot sun, we could predict he
would be at the top of the predicted range (elevated temperature elevates metabolic rate!).
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