Substrate Metabolism and Energy Balance - Is a Calorie really a Calorie

Question 1

state the 3 components of energy expenditure (EE), and the relative percentages of EE that they take up

Answer 1

1) PAEE: 10-15%
2) DIT: 10%
3) RMR: 65-75%

Question 2

can we store more fat or carbs in the human body?

Answer 2

the human body can store far more fats than it can carbs

Question 3

state 2 facts about fat storage in the human body

Answer 3

1) 4.4g circulating the blood, 1200g stored in adipocytes, and 300g stored in muscles
2) fat stores equate to over 100,000 calories - enough energy to survive off for days and days

Question 4

how much carbohydrates are stored in the body?

Answer 4

1) 5g circulating the blood, 350-700g stored in the muscles, and 100g stored in the liver
2) carb stores add upto less that 3200 calories (a real small amount compared to fat stores)

Question 5

what does carb storage in the muscles depend upon?

Answer 5

depends on dreary intake, and endurance training status - more endurance training, for the same amount of carbs in the diet, you will store more muscle glycogen

Question 6

do liver stores seem to be affected by endurance training status too ?

Answer 6

no, the liver doesn’t seem to be affected by endurance training status like the muscles do

Question 7

state 1 fact about an obese person’s ability to store fat

Answer 7

someone who is classified as obese has a much higher capacity to store fats than other individuals

Question 8

what is leptin ? (2 points)

Answer 8

1) a hormone secreted by the adipocytes which surpasses appetite
2) helps control BW in a negative feedback loop - more adipocytes = more leptin, less adipocytes = less leptin

Question 9

state 2 facts about people with leptin deficiency

Answer 9

1. completely lack the production of leptin, meaning their appetite is huge
2. 98% of people are not affected by this

Question 10

what gene is linked to leptin deficiency ?

Answer 10

the FTO gene - it works by appetite

Question 11

what do we know about the FTO gene ?

Answer 11

we know that the FTO gene works by appetite. people who have this gene have a much larger appetite than those who don’t, and struggle enormously with weight control

Question 12

explain the study design by (Stubbs et al., 2014) about how measuring energy intake is not easy

Answer 12

• got volunteers who agrees to be locked in a room for a couple of days and studied them under different conditions
• under some conditions, the participants were told the they were being observed, under others occasions they tried to blind that from them

Question 13

what does the blue bar represent in the results figure published by (Stubbs et al., 2014) in his study on measuring food consumption?

Answer 13

represents the actual amounts that were eaten as determined by the researcher who was giving them food (AKA - most accurate).

done covertly, participants unaware that they were being observed

Question 14

what does the red bar represent in the results figure published by (Stubbs et al., 2014) in his study on measuring food consumption?

Answer 14

shows overt one where researchers still weighed the food, but participants changed their behaviour and started to eat approx. 5% less calories on average

Question 15

what does the green bar represent in the results figure published by (Stubbs et al., 2014) in his study on measuring food consumption?

Answer 15

shows when the participants weighed their own food, they reported 10% less than the most accurate value

Question 16

what does the purple bar represent in the results figure published by (Stubbs et al., 2014) in his study on measuring food consumption?

Answer 16

shows if you recall participants what they ate the day prior, it leads to about 15% less calories being recalled

Question 17

what does the orange bar represent in the results figure published by (Stubbs et al., 2014) in his study on measuring food consumption?

Answer 17

shows the use of a food frequency questionnaire (FFQ) and is about 20% different to from the true values

Question 18

what is the issue with overt measures ?

Answer 18

when you do an overt measurement, you get an observation bias - the participants change their behaviour

Question 19

what is the take home message from (Stubbs et al., 2014) ?

Answer 19

the method you use to track energy consumption is very important due to the inaccuracies of some methods used

Question 20

explain a study done by (Shai et al., 2008) on changing body composition (4 points)

Answer 20

1) low fat vs low carb diet
2) 24hr recall to estimate EE
3) both groups reported 1000 kcal deficit (and a year later)
4) FFQ showed 600 kcal, and 200 kcal 6 months later

Question 21

explain the results found by (Shai et al., 2008) on changing body composition (4 points)

Answer 21

• if data true, should equal 30kg weight loss, but was only 0.7kg in low-fat diet group
• re-analysed data and found deficits get smaller over time
• if believed self-reported data, we should start to worry whether a calorie is a calorie
• issue was with the method of measurement, and not in the underlying physiology

Question 22

what are the calories found in 1 gram of the following:

1) carbohydrates
2) proteins
3) fats
4) ethanol

Answer 22

1) carbohydrates = 4 kcal/gram
2) proteins = 4 kcal/gram
3) fats = 9 kcal/gram
4) ethanol = 7 kcal/gram

Question 23

explain a study design done by (Stubbs et al., 1995) at Cambridge university

Answer 23

• locked students in a room
• put on wither low, mod, or high fat diets
• measured EI and EE
• measured the carb and fat balance of both the groups too (diff between amount of nutrient ingested vs amount of nutrient expended)

Question 24

what were the results from the study done by (Stubbs et al., 1995) at Cambridge university

Answer 24

• not a large diff in fat carb balance, but large diff in fat
• one reason = when we manipulate carb content of a diet, our metabolism also alters (more carbs = more burning of carbs)

Question 25

explain a study done by (Astbury., et al 2010) on a ‘pre-load’ technique

Answer 25

• the types of calories we eat affect both our appetite and our metabolism
• study gave participant a protein shake an hour before lunch as a ‘pre-load’
• measured how many calories were ingested at lunch

Question 26

explain the results found in the study done by (Astbury., et al 2010) on a ‘pre-load’ technique

Answer 26

• as they inc^ protein content in the pre-load, the total calories ingested at lunch decreased
• higher protein intake seems to be liked with lower appetite and lower energy intake

Question 27

state what it is meant by the key term - ‘direct calorimetry’

Answer 27

measures the heat production of an individual, in calories, when placed in an insulated chamber where the heat is transferred to surrounding water

Question 28

state 2 issues with direct calorimetry

Answer 28

1. inability to measure rapid changes in metabolism
2. friction developed by ergometer would contribute to total heat produced during exercise
3. not all heat produced during exercise would be immediately liberated from the body
4. cannot determine which fuel source is being utilised at one time - only measures metabolic rate

Question 29

state what it is meant by the key term - ‘indirect calorimetry’

Answer 29

calculates the heat that living organisms produce by measuring either their production of carbon dioxide and nitrogen wastes or from their consumption of oxygen

Question 30

state 2 minor issues with indirect calorimetry

Answer 30

1. expensive
2. inconvenient for the athlete
3. alters behaviour
4. cannot be worn for extended periods

Question 31

sate, and explain, 3 major issues with indirect calorimetry

Answer 31

1) intensity - intense exercise produces acidosis - our bicarbonate system buffers that - gives off more CO2 as a result - excess CO2 was not from our metabolism
2) conversion/production/oxidation of other substrates (e.g. - gluconeogenesis RQ = 0.13)
3) duration of exercise (steady state) - require at least 3 mins of exercise to get an accurate measure of substrate metabolism

Question 32

what piece of equipment can be used for indirect calorimetry

Answer 32

‘Douglas bag’

Question 33

state what it is meant by the key term - ‘Douglas bag’

Answer 33

an inflatable bag used to collect expired air for the determination of oxygen consumption and basal metabolic rate (BMR)

Question 34

state what it is meant by the key term - ‘Double Labelled Water’ (DLW)

Answer 34

can be used as a method to measure the average daily metabolic rate of an organism over a period

Question 35

what is the average error of DLW relative to direct calorimetry

Answer 35

DLW has an average 1-5% error relative to direct calorimetry

Question 36

state how DLW is carried out (4 points)

Answer 36

1) based upon the use of stable isotopes of Hydrogen (H) and Oxygen (O)
2) when Deuterium (2H) and 18 O are introduced into the body, they mix in with the normal H and O
3) the 18 O is lost more rapidly than the 2H as is lost in both CO2 and H2O whereas the 2H is only lost in H2O
4) the difference in those rates is used to calculate CO2 production

Question 37

state 2 disadvantages over the use of DLW

Answer 37

1. high cost of equipment and very specialised staff are required to perform the analysis
2. assumed the RER/RQ
3. no info on the components of EE
4. DLW provides no info on the pattern or intensity of PA
5. only get an average EE over the period - cannot understand daily fluctuations

Question 38

state 4 facts about - ‘activity diaries and recall questionnaires’

Answer 38

• mostly self-reported but can also be experimenter administrated
• usually utilise 10-15 min recording periods throughout the day
• many different recall questions
• used either an activity core of a MET value for recorded activity to estimate EE

Question 39

who came up with the - ‘Compendium of Physical Activity’

Answer 39

(Ainsworth et al., 1993; 2000; 2011)

Question 40

what is the ‘Compendium of PA’ (Ainsworth et al., 1993; 2000; 2011)

Answer 40

• compromised from a variety of published and un-published sources
• element of subjectivity required in both internal record of activity by the participant and the condor
• uses average of values for various activities

Question 41

how does the ‘Compendium of PA work’ ?

Answer 41

1) 1 MET = BMR
2) therefore, the multiplication of a MET by the time will estimate EE
3) e.g. - 1.5 kcal/min (BMR) x 3 MET’s = 3.5 kcal/min/ ANS x 15 mins = 67.5 calories burnt

Question 42

state 1 benefit and 1 drawback over the use of ‘pedometers’ and ‘accelerometers’

Answer 42

• both very good at predicting EE during ambulatory activities (e.g. - running and walking)
• doesn’t pick up data from non-ambulatory activities (e.g. - cycling)

Question 43

state 1 benefit and 1 drawback over the use of ‘HR monitors’

Answer 43

• aim to pick up on info accelerometers miss - estimate EE on linear relationship between HR and EE (however, linearity is lost at low intensities)
• HR monitors require individual calibration and other factors can influence their results (e.g. - stress)

Question 44

state what it is meant by the key term - ‘actiheart’

Answer 44

tech uses a combination of HR and accelerometry data . as sources of error are different for the two methods, it should theoretically become more precise

Question 45

state what it is meant by the key term - ‘sensewear armbands’

Answer 45

worn on the upper arm; has measures of heat flux, bi-axial accelerometer, skin temp, and much more. the calculation for measuring EE is proprietary