weight management

Question 1

what is the SI unit (international) for food energy?

Answer 1

joule (J)

• energy used when a mass of 1kg is moved through 1 meter by a force of 1N

Question 2

what is the non-SI unit for food energy?

Answer 2

calorie (cal)

• energy required to raise temp of 1g of water by 1*C
• kcal the same but 1kg of water

Question 3

what is the energy balance equation?

explain it?

Answer 3

energy intake = energy expenditure (doesn’t change much unless high intensity exercise) +- energy stored

if intake

Question 4

what does 1kcal=?

Answer 4

4.2kJ

Question 5

how to measure total energy value of food?

Answer 5

bomb calorimeter:

chamber in water bath
put food in and burn it in presence of O2
heat of combustion will raise water temp and can then determine calories in that food

but protein not fully combustible (into CO2 and water) so energy not the same

Question 6

what is metabolisable energy?

what is it limited by?

Answer 6

energy actually supplied to tissue by each food

some not digested or leaves as faeces, or nitrogen in urine

Question 7

what are the atwater factors of CHO, protein, fat and alcohol?

why is it not just 1 value?

Answer 7

CHO - 4 kcal/g
protein - 4
fat - 9 (energy dense)
alcohol - 7

value differs for different types of the macronutrient e.g saturated and unsaturated fats and different amino acids

Question 8

what are the 3 main components of energy expenditure?

Answer 8

1) basal/resting metabolic rate (60-70% of total energy expenditure)
2) physical activity (EEA) (25-30%) mainly made up of non-exercise activity thermogenesis (not proper exercise)
3) diet-induced thermogenesis (DIT) - increase in metabolic rate after a meal due to ensuing processes e.g digestion and absorption

Question 9

describe basal metabolic rate as a main component of energy expenditure?

what are the main contributors to it?

Answer 9

minimum level of energy to sustain vital funcitons in the waking state

• heart and respiratory functions
• protein turnover 25% (large amount of fat free mass then high metabolic rate as lots of turnover)
• fat&carb turnover
• maintenance of ion gradients across membranes

Question 10

how to measure basal metabolic rate?

Answer 10

in supine position (lying face up)
thermoneutral enviro
after 8h sleep and 12h fasting

Question 11

describe diet induced thermogenesis as a main component of energy expenditure?

what are the 2 types?

Answer 11

energy required to digest, absorb, and assimilate food nutrients

1) obligatory thermogenesis - of protein (the most), fat and carbs
2) adaptive or facultative thermogenesis - increase in sympathetic nervous system activity in response to feeding

Question 12

describe the thermic effect of exercise as a main component of energy expenditure?

Answer 12

EEA is 10% of EE in sedentary and 15-30% in athlete

Question 13

describe the thermic effect of illness as a main component of energy expenditure?

examples?

exception?

Answer 13

injury leads to increase in basal metabolic rate

e.g mending bone fracture and third degree burns increase BMR

starvation reduces basal metabolic rate

Question 14

when does obesity occur?

Answer 14

when energy intake>energy expenditure

over a prolonged period of time

Question 15

what is BMI?

Answer 15

body weight in kg/height in meters^2

Question 16

what is the definition of obese in terms of BMI?

Answer 16

obese = 30-40 BMI

Question 17

what is another way of measuring obesity?

how would it define obesity?

Answer 17

measuring the amount of body fat, especially around abdominal region to determine risk

obesity=too much body fat as starts to accumulate in different parts of body e.g abdominal region

Question 18

what is one of the main reasons for increased energy intake beyond a healthy level?

Answer 18

homeostatic systems of energy intake impaired

e.g don’t know when next meal is so store it all

Question 19

what is the role of the hypothalamus in eating?

what happens in obesity?

internal factors influencing energy intake

Answer 19

hypothalamus controls hunger and satiety (stop eating)

• has desire to eat and contains pathway to stop this desire

Question 20

what happens to the hypohalamus in obesity?

internal factors influencing energy intake

Answer 20

obesity:
becomes resistant to leptin (stop eating message) due to always eating in obesity so can eat more without being full

reduced gut hormone releasedso don’t feel full when we are

impaired hypothalamic signalling

Question 21

what are 4 external factors influencing energy intake?

Answer 21

1. psychological - reward/pleasure pathways (always room to desert), palatability
2. cost - cheap foods energy dense
3. convenience/time of day - snacks energy dense
4. social and peer pressure

Question 22

what are some risk factors for obesity?

2 main groups and subgroups of these?

Answer 22

1. genetic
   - monogenic syndromes e.g leptin deficiency due to lack of gene to produce it
   - genetic susceptibility
2. environmental
   - diet e.g fat (passive overconsumption of food), sugar and alcohol
   - socio-economic status
   - no physical activity