Metabolism
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Starving to slim
EW is 26 years old. She weights 90 kg and is 1.52 m tall, and is about to undergo elective surgery.
What is her body mass index?
Body mass index (BMI) = weight in kg / (height in metres squared).
= 90 / (1.52 x 1.52) = 38.9
You would classify her as being obese
A desirable range of BMI is 20 - 25. If she is to achieve a BMI of 25, what should she weigh?
If BMI = weight / height-squared then weight = BMI x height-squared = 25 x (1.52 x 1.52) = 57 kg
If her target weight is 57 kg then she has to lose 33 kg.
The energy yield of adipose tissue can be calculated from the fact that it contains 80% triacylglycerol (at 37 kJ /gram) and 5% protein (at 17 kJ /gram). Therefore 100 g of adipose tissue yields:
from triacylglycerol: 80 x 37 = 2960 kJ
from protein: 5 x 17 = 85 kJ
total = 3045 kJ = 3.045 MJ / 100 g adipose tissue = 30 MJ / kg adipose tissue (rounding off)