W9: Diet Flashcards
What is the rationale behind Bioelectric Impedance Analysis (BIA) to measure body composition (fat/muscle/water content etxetc)? How does it work?
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)
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?
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
What are the 3 components of energy expenditure and how many percent of energy expenditure do they contribute to?
- Thermic effect of food: 10%
- Physical activity: 30-50%
- Basal metabolism : 50-65%
What is resting metabolic rate?
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
What is basal metabolism rate (BMR)?
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
What is the main difffernece between BMR and RMR?
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.
Which groups of people have higher BMR? [4]
- Younger people
- Taller people
- People with more lean mass (more muscles which use up more energy)
- Males
What conditions / substances raises BMR? [6]
- Fever
- Stress
- Heat
4. Cold - Nicotine – blood rushing and feel high
- Caffeine
What conditions lowers BMR? [3]
- Starvation
- Malnutrition
- Sleep
conditions where no food intake / insufficient food intake to conserve energy
What is meant by the thermic effect of food?
The energy required to digest food
For every 2000kcal of energy intake, how many kcal is needed to digest food?
200kcal (bc 10%)
Why is thermic effect of food usually not included in the Estimated Energy Requirements?
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
What is the recommended BMI for healthy weight?
18.5 - 24.9
What constitutes reasonable weight loss? [2]
Losing at least 10% of initial weight + maintaining weight loss for 1 year
What are the 2 main weight loss strategies?
- Eat a healthy diet
- Physical activity
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?
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.
Weight loss : eating patterns
In changing my eating patterns for weight loss and maintenance, what are 5 tips?
- Be realistic about energy intake, dont reduce calories by too much, and ensure nutritional adequacy
- Drink more water = more full and hydration
- Select carbs carefully = reduce added sugars / artificial sweeteners and increase fibre intake
- Choose fats sensibily = healthy fats only
- Watch out for empty calories (fat, sugar, alcohol)
What is the best weight loss and maintenance strategy?
Diet + physical activity
What are the benefits of diet + increase physical activity when it comes to weight loss and maintenance?
- Lose more fat, including abdominal fat– due to more healthy eating + using fat for fuel during exercise
- Retain more muscle – increase muscle mass which will expend more energy, increasing BMR
- Estimated energy requirements (EER) will increase – increase in discretionary calories – if dont use up all the space in discretionary calories, weight loss can occur
If i eat a healthy diet + do physical activity, I will definitely lose weight. True or False?
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.
What are the 2 components of estimated energy requirements? (EER)
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!!
Does it take more effort to prevent weight gain or weight regain?
Weight regain, where i gain back all that i lost
- weight gain may occur due to increase in muscle msss
