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Diet and nutrition > Energy > Flashcards

Energy Flashcards

1
Q

Measure energy expenditure: Direct Calorimetry?

A

Calorimeter

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2
Q

Measure energy expenditure: Indirect Calorimetry?

A

Open-circuit Spirometry—>

Portable systems Douglas bag Computerised (breath-breath)

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3
Q

Measure energy expenditure: Stable Isotopes?

A

2H+18O—>

Doubly labelled water (2H2 18O)—>

Ingestion—>

Distribution (5h)—>

Excretion: Urine (2H+18O) + Breath( 18O)

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4
Q

Measure energy expenditure: Prediction Equations

A

Prediction equations

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5
Q

Components of energy expenditure?

A
  1. Basal Metabolic Rate
  2. Thermic Effect of Food
  3. Thermic Effect of Activity
  4. Growth (children, pregnancy)
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6
Q

Basal Metabolic Rate: A measure of an individual’s metabolism in a basal state?

A

– Immediately after waking (awake)

– Lying supine (eg resting),

– Fasted (all food digested/absorbed, eg >12h fast)

– Thermally neutral conditions

– (eg. no other physical or psychological stimulation).

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7
Q

Basal Metabolic Rate: Reflects energy required for:

A

– Breathing / circulation / ion pumps (eg normal bodily functions)

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8
Q

Basal Metabolic Rate: part 3?

A
  • Requires specialist equipment to measure directly
  • Several prediction equations
  • BMR typically accounts for 40-70% energy expenditure.
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9
Q

Resting Metabolic Rate (RMR)?

A
  • Failure to meet above conditions (eg arousal component)

* >BMR by ~10%

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10
Q

RMR in athletes: Background?

A

• Contribution of metabolic rate to total

EE varies depending on activity level.

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11
Q

RMR in athletes: Method?

A
  • 10 female endurance runners v 10 sedentary controls.

* Thermic effect of meal (TEM) and thermic effect of activity (TEA).

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12
Q

RMR in athletes: Conclusion

A

• RMR accounted for 47% of energy expenditure in athletes compared to 61%
in sedentary controls.

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13
Q

Factors that influence BMR: Age?

A
  • Declines by ~1-2% by year from 20 to 70yr

* Linked to muscle loss and brain weight

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14
Q

Factors that influence BMR: Gender?

A
  • Menstrual cycle fluctuations (100 – 300kcal/d)

* Males > Females (body composition)

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15
Q

Factors that influence BMR: Body Size?

A
  • Fat-free mass

* Muscle is very metabolically active

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16
Q

Factors that influence BMR: Exercise?

A
  • Alterations in fat-free mass
  • Muscle damage
  • EPOC (intensity/duration dependent)
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17
Q

Factors that influence BMR: Nutritional Status?

A

• Undernutrition

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18
Q

Factors that influence BMR: Psychological factors?

A

• Anxiety can increase BMR

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19
Q

Factors that influence BMR: Hormonal factors?

A

• Hypothyroidism reduces BMR

20
Q

Factors that influence BMR: Disease/Injury?

A

• Trauma, fever, injury increases BMR

21
Q

Energy Availability: Methods?

A
  • 8 males completed 4 x 9d exercise& diet interventions

* Ex = 3 x 40min cycle/d

22
Q

Energy Availability: Results?

A

• Energy Availability ~30kcal/kg FFM

23
Q

Energy Availability: Conclusion?

A

• Energy balance decreased by 90kcal/d towards zero indicating the slowing of various metabolic processes. This leads to detrimental health affects.

24
Q

Prediction Equation: Method?

A
  1. Harris-Benedict (1919)
  2. Cunningham (1980)
  3. Owen et al (1986, 1987)
  4. Mifflin et al (1990)
  5. WHO (1985)
25
Prediction Equation: Results?
• All prediction equations underestimated RMR except for the Cunningham equation (Why do you think this is?)
26
Prediction Equation: Critical Analysis?
* Recognise the limitations of these predictive equations * Study population v New population * Age, height, weight, FFM, gender * Activity (Athletes v sedentary)
27
Components of energy expenditure?
1. Basal Metabolic Rate 2. Thermic Effect of Food 3. Thermic Effect of Activity 4. Growth (children, pregnancy)
28
Thermic Effect of Food?
* The increase in EE above RMR that occurs due to the ingestion of food * Typically accounts for 6-10% of daily EE. * Includes the energy required for: 1. Digestion 2. Absorption 3. Transport 4. Metabolism 5. Storage
29
Thermic Effect of Food: Dietary Factors affecting TEF?
1. Protein 2. Carbohydrate 3. Fat
30
Thermic Effect of food: Method?
* PLA meal vs 400kcal meal consisting of CHO, FAT, PRO | * Metabolic Rate - Indirect calorimetry (90min)
31
Thermic Effect of food: Results?
• All test meals increased metabolic rate with the greatest seen in protein, then carbohydrate and then fat.
32
Thermic Effect of food: Discussion?
• This is a result of the lower energy requirement to store fat as TG, than proteins (synthesis of new AA) and carbohydrate (storage as glycogen)
33
Thermic effect of activity: Physical activity ratio?
• Energy cost of activity : BMR
34
Thermic effect of activity: Physical Activity Level?
* Daily total energy expenditure : BMR | * Old method (summed PAR, SPA?)
35
Thermic effect of activity: Metabolic Equivalents (MET’s)?
• Work metabolic rate : RMR • A fixed rate of oxygen consumption assumed to represent that of an adult measured during supine rest • 1 MET is equivalent to 3.5ml/kg/min (~1kcal/kg/h)
36
PAL Matrix for EAR: Assumptions in EAR?
* Basal Metabolic Rate | * Schofield et al (1985) Equation
37
PAL Matrix for EAR: Physical Activity Level?
• Sleeping – 8h/24hr • Occupation – (7.5h/24h for 5d = 5.5h/7d) ``` • Non-occupational (10.5h) – 8.5h x 1.4PAR plus: – Non-active – 2h at 2PAR – Mod active – 2h at 3PAR – Very active – 2h at 4PAR ```
38
Establishing the EAR?
• An EAR is reported for energy, not the RNI as the RNI would represent an excess energy intake for most of the population. Due to a skewed distribution (sedentary) the median, not mean, is used.
39
Establishing the EAR: Calculations?
• Derived from doubly labelled water and basal metabolic rate (Henry 2005) • PAL - 1.49 (25th centile) – Less active(immobile) • PAL = 1.63 – Average activity • PAL = 1.78 (75th centile) – More active – (eg those trying to increase activity levels)
40
Establishing the EAR: Considerations - Physical Activity Level?
* +0.15PAL - 30min moderate intensity exercise ≥5d/wk * +0.20PAL – 60min brisk walking (4-5mph, daily) * +0.30PAL - 60min active sport 5times/wk * +0.40PAL – 60min jogging (6mph, daily) * +0.60 PAL - 60min of intense aerobic sport 5 times/wk
41
Current Energy Intake & DRV in the UK: Considerations for DRV?
• A level to maintain a healthy body mass in healthy people at their existing levels of physical activity. • Recognises overweight/obesity prevalence
42
Current Energy Intake & DRV in the UK: Current UK Intake?
* Men = 8.88 ± 2.58MJ/d (~2111kcal/d) | * Women = 6.78 ± 1.91MJ/d (~1613kcal/d)
43
Metabolisable energy?
Gross Energy: unabsorbed----> Digestible energy: Incomplete catabolism's---> Metabolisable energy Protein: 5.65kcal/g---> 92%---> 4kcal/g Fat: 9.40kcal/g---> 95%---> 9kcal/g Carbohydrates: 4.10kcal/g---> 97%---> 4kcal/g
44
Dietary energy sources: Conversion factors?
* 1 kcal = 4.184kJ | * 1kJ = 0.239kcal
45
Dietary energy sources: Macronutrients?
* Protein – 4kcal/g * Carbohydrate – 4kcal/g * Fat – 9kcal/g * Alcohol – 7kcal/g

Diet and nutrition (8 decks)

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