W9: Diet

Question 1

What is the rationale behind Bioelectric Impedance Analysis (BIA) to measure body composition (fat/muscle/water content etxetc)? How does it work?

Answer 1

Rationale
- **organs and tissues **are semi or non conductors of electricity
- Water is conductor of electricity, has high resistance and low impedance
- Fat is a bad conductor of electricity.
- Measurement of fat/muscle/water by looking at electrical conductance

How it works
- Person stands on a machine and holds 2 electrodes for a few minutes, and body mass / fat mass / muscle mass / water content in body is measured. (Like the body composition measurement we did in sch)

Question 2

Field methods (e.g. BMI/bioelectrical impedance) or lab methods (densitometry – BodPod) are estimates of body compositions. What is the name of the laboratory method that is the gold standard in measuring body composition?

Answer 2

DEXA, Dual energy X-ray Absorbimetry
- able to differentiate soft tissue, fat tissue and bone tissue (different types of tissue), and even measure bone density

Question 3

What are the 3 components of energy expenditure and how many percent of energy expenditure do they contribute to?

Answer 3

1. Thermic effect of food: 10%
2. Physical activity: 30-50%
3. Basal metabolism : 50-65%

Question 4

What is resting metabolic rate?

Answer 4

Amount of energy the body burns while at rest, including basic functions like breathing and digestion, and low-effort activities like walking.
- includes activities of daily life

Question 5

What is basal metabolism rate (BMR)?

Answer 5

Basal metabolism rate: energy needed to maintain life when body is at complete digestive, physical and emotional rest. Requires 12h of fasting and restful sleep
- bare minimum amount of energy for survival

Question 6

What is the main difffernece between BMR and RMR?

Answer 6

BMR is more stringent than RER, where person needs to be at complete rest while RMR is less stringent where person can eat/move around and does not require a certain duration of fasting.

Question 7

Which groups of people have higher BMR? [4]

Answer 7

1. Younger people
2. Taller people
3. People with more lean mass (more muscles which use up more energy)
4. Males

Question 8

What conditions / substances raises BMR? [6]

Answer 8

1. Fever
2. Stress
3. Heat
   4. Cold
4. Nicotine – blood rushing and feel high
5. Caffeine

Question 9

What conditions lowers BMR? [3]

Answer 9

1. Starvation
2. Malnutrition
3. Sleep

conditions where no food intake / insufficient food intake to conserve energy

Question 11

What is meant by the thermic effect of food?

Answer 11

The energy required to digest food

Question 12

For every 2000kcal of energy intake, how many kcal is needed to digest food?

Answer 12

200kcal (bc 10%)

Question 13

Why is thermic effect of food usually not included in the Estimated Energy Requirements?

Answer 13

The total energy output from thermic effect of food (10%) may be negligible, as 10% may be smaller than % error in EER calculations
- e.g. If EER calculation % error = 15%, then thermic effect of food (10%) is insignificant

Question 14

What is the recommended BMI for healthy weight?

Answer 14

18.5 - 24.9

Question 15

What constitutes reasonable weight loss? [2]

Answer 15

Losing at least 10% of initial weight + maintaining weight loss for 1 year

Question 16

What are the 2 main weight loss strategies?

Answer 16

1. Eat a healthy diet
2. Physical activity

Question 17

In trying to lose weight and maintaining it in the long run, it is most effective if I restrict my calories by eating hypocaloric diet, such as a low fat diet. True or False? Why?

Answer 17

False.
- If I lower my calories by too much, my Resting Energy Expenditure (REE) and BMR will reduce significantly to conserve nutrients since I am **eating less **(assuming my physical exercise is lowand didnt change).
- At the same time, my **leptin hormone level (full hormone) will decrease **and grhelin hormone increases (hunger), so I will be more likely to want to snack.
- With my lowered REE and BMR if I eat my old diet, I will regain all the weight easily.

Question 18

Weight loss : eating patterns

In changing my eating patterns for weight loss and maintenance, what are 5 tips?

Answer 18

1. Be realistic about energy intake, dont reduce calories by too much, and ensure nutritional adequacy
2. Drink more water = more full and hydration
3. Select carbs carefully = reduce added sugars / artificial sweeteners and increase fibre intake
4. Choose fats sensibily = healthy fats only
5. Watch out for empty calories (fat, sugar, alcohol)

Question 19

What is the best weight loss and maintenance strategy?

Answer 19

Diet + physical activity

Question 20

What are the benefits of diet + increase physical activity when it comes to weight loss and maintenance?

Answer 20

1. Lose more fat, including abdominal fat– due to more healthy eating + using fat for fuel during exercise
2. Retain more muscle – increase muscle mass which will expend more energy, increasing BMR
3. Estimated energy requirements (EER) will increase – increase in discretionary calories – if dont use up all the space in discretionary calories, weight loss can occur

Question 21

If i eat a healthy diet + do physical activity, I will definitely lose weight. True or False?

Answer 21

True to a certain extent
- in the short run, since fat is lost through maintaining healthy diet + exercise, i will lose weight from fat loss.

• However, in the long run, weight is maintained. Though weight is lost through losing fat, my weight will increase due to increase in muscle mass, so my weight will stabilise after a while and wont keep on dropping.

Question 22

What are the 2 components of estimated energy requirements? (EER)

Answer 22

Energy intake to meet nutrient needs + discretionary calories
- EER includes physical activity in the eqn, thus with exercise, EER will increase due to increase in discretionary calories space!!

Question 23

Does it take more effort to prevent weight gain or weight regain?

Answer 23

Weight regain, where i gain back all that i lost
- weight gain may occur due to increase in muscle msss