Energy Balance

Question 1

What is energy?

Answer 1

It is the capacity to do work.

Question 2

Give the 2 methods of measuring energy in food. Explain the difference between the two.

Answer 2

Direct - using a calorimeter
Indirect - using the food composition table and oxycalorimetry

Question 3

How many joules is in 126 kcal?

Answer 3

1 kcal/cal = 4.184 J
126 kcal x 4.184 J/1 kcal = 527.184 J or 527 J

Question 4

Who pioneered bomb calorimetry?

Answer 4

Antoine Lavoisier

Question 5

Explain the concept of bomb calorimetry in one sentence.

Answer 5

The amount of energy released by carbohydrate or fat when burned is the same as the amount of energy metabolized by the body when ingested.

Question 6

Implication of bomb calorimetry.

Answer 6

Energy in food (cal) is the amount of energy produced in the body via food metabolism.

Question 7

Which macronutrient has the least %Digestibility?

Answer 7

Protein

CHO: 98%
PRO: 92%
Fat: 95%

Question 8

It is defined as the ratio of carbon dioxide production to oxygen consumption.

Answer 8

Respiratory Quotient (RQ)

Question 9

The method of measuring energy in food that estimates energy expenditure via determination of O2 consumption and CO2 production in a given time period.

Answer 9

Indirect calorimetry

Question 10

A modification of the respiratory chamber that uses thermocouples and a heat exchange disc attached to the subject’s skin.

Answer 10

Metabolic chamber

Question 11

A method of measuring energy in food by measuring heat given off by the body using a respiratory chamber.

Answer 11

Direct calorimetry

Question 12

Give the RQ of Fat

Answer 12

Fat RQ = 0.70

Question 13

Among the three macronutrients, which has the highest RQ?

Answer 13

Carbohydrates

CHO RQ = 1.00
PRO RQ = 0.82
Fat RQ = 0.70

Question 14

Differentiate: Direct calorimetry and Indirect calorimetry

Answer 14

Direct calorimetry measures the heat released (energy used) by the body using a respiratory chamber whereas indirect calorimetry only estimates energy used by the body via determination of oxygen consumption and carbon dioxide production in a given time frame.

Question 15

Enumerate the three components of energy expenditure.

Answer 15

1. Basal Metabolic Rate (BMR)
2. Physical Activity (PA)
3. Thermic effect of food (specific dynamic activity of food)

Question 16

Which among the three components of energy expenditure has the highest percentage relative to TEE?

Answer 16

Basal Metabolic Rate: 60-65%

Question 17

What are the different parts of a bomb calorimeter and their respective functions?

Answer 17

Oxygen supply = provides oxygen
Ignition wires =
Stirrer = equalize temperature of water
insulating jacket = ensures that the system is closed
bucket = contains the water
heater =
water =
air space = separates the water from the insulating jacket
crucible = sample container
steel bomb = separates the water from the sample
ignition coil = provides heat
magnifying eyepiece =
thermometer =

Question 18

What is the energy value of food determined byte the bomb calorimeter referred as? It is also the maximum amount of energy, measured as heat, which the food is capable of yielding under controlled conditions that favor complete oxidation.

Answer 18

Heat of combustion

Question 19

Give the two reasons why the human body is not efficient in utilizing food for energy.

Answer 19

1. The body cannot digest, absorb, and metabolize nutrients efficiently at 100%. This means that the extent to which the ingested food is available for the cell must be taken into account to determine the energy available from the source.
2. Metabolizable energy or the physiological fuel value. Carbs, fat and alcohol are oxidized completely in cellular metabolism but nitrogen from protein is not resulting in a 1.25 kcal/g of protein lost.

Question 20

This method of determining the amount of heat produced by the body is done by measuring the change in temperature of a known volume of water circulating in pipes at the top of the chamber. It is expensive and only few calorimeters for this method are available globally.

Answer 20

Respiratory chamber

Question 21

True or False: A patient with an RQ of 1.00 is underfed.

Answer 21

False. An RQ of 1.0 means that the body is dependent on carbohydrate stores for energy. When carbohydrates are utilized, this means that there is enough carb source in the body and the patient is either well-fed or overfed. Underfeeding results in a low RQ.

Question 22

True or False: Thermic Effect of Food (TEF) or Dietary-Induced Thermogenesis was earlier known as Specific Density Action (SDA)

Answer 22

False. Specific Dynamic Action

Question 23

Differentiate: Basal Metabolism and Basal Metabolic Rate

Answer 23

Basal Metabolism refers to the energy requirements of of physiological activities during the post-absorptive state. Meanwhile, basal metabolic rate refers to the rate at which the body spends energy for the maintenance of physiological activities.

TLDR, basal metabolism talks about energy requirement at rest while BMR is the frequency of energy expenditure for the maintenance of physiological activities.