Energy Balance and Dietary Assessment Lecture Five

Question 1

What are the three types of Energy loss from the body?

Answer 1

Resting Metabolic Rate (RMR)
Diet Induced Thermogenesis
Physical Exercise

Question 2

How does RMR influence daily energy loss?

Answer 2

In the average person it makes up 60-70% of the daily energy loss.

Energy used for:
Active transport (Pumps)
CNS activity
Thyroid Hormone production (linked with metabolic rates)

Question 3

What is RMR also called?

Answer 3

Basal Metabolic Rate

Question 4

If someone was to only be undergoing RMR what conditions would they need to be in?

Answer 4

Warm
Lying
Not asleep or eating.

Question 5

What increases BMR?

Answer 5

Muscles mass (less fat, more lean)
Body Surface Area (larger=higher BMR)
Aging (decreases it)
Body Temperature (increase C = Increased BMR)
Stress (increase BMR)
Higher Levels of thyroxine and adrenaline increase BMR

Question 6

What is diet induced thermogenesis?

Answer 6

Increased body temperature that occurs after eating a meal (as a result of digestion, absorption, metabolism and storage of food)

10% on average

Question 7

What defines physical activity?

Answer 7

Any energy expenditure not associated with RMR or DIT

Question 8

What bulk of daily energy expenditure does physical activity make up?

Answer 8

Most highly variable energy expenditure.

100k/cal in sedentary person to 8000k/cal in a elite cyclist

Shivering, fidgeting included

Question 9

When comparing two individuals the percentages of energy expended are?

Answer 9

Both equal 100%

Even if the total energy expended is drastically different.

Question 10

Of a person who is physically active, what percentage energy expended changes?

Answer 10

Physical activity has the largest energy expenditure while DIT remains around 10% and RMR decreases slightly.

Question 11

How much energy relative to RMR does a sedentary lifestyle expend?

Answer 11

About 1.5x

Question 12

How many calories are needed to support a sedantery lifestyle?

Answer 12

1200-2400 kcal

Question 13

How many calories do some examples of athletes need?

Answer 13

Uni student 2000-6000 kcal
Cyclist 6000-9000 kcal
Marathon Runner ~4000 kcal

Question 14

What is an important concept regarding energy intake for an athletes goal?

Answer 14

Energy intake vs Energy output = Energy Balance

Leads to weight maintenance, loss or gains

Question 15

How is direct calorimtery measured in humans?

Answer 15

Very difficult, involves a room, person exercising and changes in temperature while trying to keep a range of variables constant

Question 16

How is indirect colorimetry achieved in humans?

Answer 16

Measuring Rate of respiration, volume of gases inhaled and exhaled. % of oxygen and carbon dioxide out/in.

Can determine how much fat/CHO burned.

Question 17

How can indirect calorimetry result in the determination of how much fat of CHO burned?

Answer 17

CHO burns 1:1 i.e for glucose 6 O2 for 6 CO2

Fats burn 23:16

This is referred to as the RER respiratory Exchange Ratio

Question 18

What are some examples of indirect colorimetry?

Answer 18

Douglas bag
Respiration Chamber
Spiromerty

Question 19

What hinders spirometry, when trying to determine energy burned?

Answer 19

Hyperventilation
Anaerobic respiration

Prevent interpretation of results.

Question 20

Following spirometry what are other methods of determining energy expenditure?

Answer 20

Spirometry (Best for indirect calorimetery)
Doubly Labelled water
Heart Rate monitor
Accelerometer and GPS

Physical activity diaries
Pedometer (Worst) Never!

Question 21

What is involved in Doubley labelled water?

Answer 21

Isotope of water, which is labelled is consumed.

Urine is analysed to determine CO2 production, as the water splits and H is excreted while oxygen forms CO2

Question 22

How does a heart rate monitor measure energy expenditure?

Answer 22

Measure energy based on the HR-VO2 relationship

Requires VO2max test
Requires constant use of Heart Rate monitors.

Not perfect, good for large groups

Question 23

What is bad about the heart rate monitor?

Answer 23

After VO2 max is achieved, the relationship between heart rate and Vo2max is no longer linear.