1. Nutrition, Diet And Body Weight 2 Flashcards
What are Dietary Reference Values (DRVs)?
- Estimates of the amount of energy and nutrients needed by different groups of healthy UK population.
- Values depend on age, gender and level of physical activity.
- Published by SACN (Scientific Advisory Committee on Nutrition).
What are the different types of DRVs?
- Estimated Average Requirement (EAR): used for energy.
- Reference Nutrient Intake (RNI): used for proteins, vitamins and minerals.
- Lower Reference Nutrient Intake (LRNI): intakes below are insufficient for most people.
- Safe intake: used when insufficient data.
What % of each studied group is EAR, RNI and LRNI appropriate for?
- EAR: requirement for ~50% of group (50% will require more).
- RNI: requirement for 97% of group (many will need less).
- LRNI: requirement for those 2.5% who have low requirements (majority will need more).
What does an individual’s energy requirements depend on?
Age, sex, body composition and physical activity.
With moderate physical activity, what is the daily energy expenditure of the average adult male and female?
- 70 kg adult male: ~12,000 kJ/day
- 58 kg adult female: ~9,500 kJ/day
What is daily energy expenditure the sum of?
- Basal metabolic rate
- Diet-induced thermogenesis: energy required to process food
- Physical activity level
What are the functions of basal metabolic rate?
Maintains resting activities of the body:
- Maintenance of cells (ion transport across membranes, biochemical reactions)
- Organ function
- Maintenance of body temperature
What is the basal tone at rest of different organs?
- Skeletal muscle: ~30% BMR
- Brain: ~20% BMR
- Liver: ~20% BMR
- Heart: ~10% BMR
- Other: ~20% BMR
Which factors affect BMR?
- Body size (surface area)
- Gender (males higher than females)
- Environmental temperature (increases in cold)
- Endocrine status (increased in hyperthyroidism)
- Body temperature (12% increase per degree)
What energy stores does the body rely on?
- Very short term energy stores of energy-rich molecules in muscle: few seconds worth.
- Carbohydrate stores for immediate use (e.g. Creatine phosphate for initial energy burst): mins-hrs depending on activity.
- Long term stores in adipose: ~40 days worth.
- Under extreme conditions, muscle proteins can also be converted to energy.
What is obesity?
- Excessive fat accumulation in adipose tissue which impairs health.
- Result of energy intake exceeding energy expenditure over a period of years.
What health problems is obesity associated with?
Increased risk of some cancers, cardiovascular disease and type 2 diabetes
How is BMI calculated?
BMI = weight (kg) / height2 (m2)
= kg/m2
How can individuals be classified according to their BMI?
<18.5 = underweight 18.5-24.9 = desirable weight 25-29.9 = overweight 30-34.9 = obese >35 = severely obese
What is the major weakness of the BMI calculator? What is an alternative measurement?
Very muscular individuals may be wrongly classified as obese.
Alternative measurement = waist:hip ratio
