Chapter 10: Energy Balance And Body Composition Flashcards by Allie Bartoletti

Energy balance/Energy Equilibrium

Intake matches expenditure

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Positive energy balance

Intake exceeds expenditure
- good things during pregnancy and growth

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Negative energy balance

Intake is less than expenditure
- good for losing weight

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KCalories per g for carbs, protein and fat

Carbs: 4 kcal/g
Protein: 4 kcal/g
Fat: 9 kcal/g

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Components of energy expenditure

Main purposes/Only way to burn calories:
1. Basal Metabolic rate
2. Physical activity
3. Thermic effect of food (digestion, absorption, processing of ingested nutrients)
Minor form of energy output is thermogenesis (shivering/fidgeting)

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Basal Metabolic rate

Minimum amount of energy required in a fasting state to keep the resting body functioning
- largest component of energy expenditure

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What organ has the highest usage of BMR while a person is at rest

Liver

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What percent of energy expenditure does basal metabolic rate account for

60-70% of total energy expenditure

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What is Resting metabolic rate (RMR)

If a person is not fasting or rested, we use RMR instead of BMR

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How are BMR and RMR expressed

The number of calories burned per unit of time
Women: 0.9 kcal/kg per hour
Men: 1.0 kcal/kg per hour

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What are some factors that may increase BMR

Muscle mass
Body surface area
Male gender
Body temperature
Secretions of thyroid hormone (hyperthyroidism)
Stress hormones
Growth stages
Caffeine, tobacco
Recent Exercise

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What are factors that may decrease BMR

Hypothyroidism
Restricted calorie intake
Less muscle mass and body surface area
Aging declines 1-2% each decade after age 30

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What happens to BMR with weight loss/gain?

Person who lost weight has a lower BMR compared to someone who maintains weight

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What is the most variable component of expenditure

Physical activity

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How much does physical activity increase kcal needs

25%-40% above BMR

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How much does the thermic effect of food account for in kcal consumed

Generally accounts for 5-10% of kcal consumed

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What is the thermic effect of food

The energy used to digest, absorb, transport, store and metabolize
- Ex: chewing
Varies by nutrient content
- Highest for protein
Also influenced by food composition and meal size

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What is adaptive thermogenesis

Not a main component of expenditure, but may contribute a small amount
Triggered by cold, overfeeding, trauma, starvation
Non-voluntary physical activity or non-exercise activity thermogenesis
- Fidgeting, shivering, holding body upright
Varies by individual; may be dependent on brown adipose tissue

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How can energy expenditure be measured

By direct or indirect calorimetry

What is direct calorimetry

Estimates energy expenditure by measuring amount of heat released by the body

What is indirect calorimetry

Collects air expired during specific time period
Considers oxygen consumed and carbon dioxide produced
Doubly-labeled water can also be used

What is estimated energy requirements

Equations based on evidence gathered through direct and indirect calorimetry

What are energy expenditure needs based on

Weight
Height
Sex
Age
Physical activity level

Hunger definition

Physiological drive to find and eat food
- Controlled by internal mechanisms such as organs, hormones, hormone-like factors and the nervous system

Appetite definition

Psychological drive to eat - impacted by external factors

What is satiety

The feeling of fullness following consumption of food - suppresses further consumption - influences time between meals - regulated by hypothalamus

What is the hypothalamus’s role in internal cues of eating behavior regulation

The hypothalamus communicates with endocrine system and nervous system Integrates internal cues of blood glucose levels, hormone secretions and sympathetic nervous system

Satiation vs. Satiety

Satiation causes us to stop eating - secretion of hormones during digestion promotes satiation Satiety occurs after eating has stopped

What hormones during digestion promote satiation

- Cholecystokinin - Glucagon-like-peptide-1 - Peptide YY (PYY)

What is satiety promoted by

Sensory aspects of food Knowledge food has been consumed Chewing Expansion of stomach and intestines Effects of digestion, absorption and metabolism Decrease in hormone ghrelin (from stomach)

What is ghrelin

Hormone - acts in the hypothalamus - promotes intake: increase appetite, increases smell sensitivity, promotes energy storage - in stomach

What is leptin

Hormone - acts in hypothalamus - signals brain to decrease intake - rises when body fat increases - leptin deficiency = constant hunger - secreted by adipose tissue - increase in adipose storage = increase in leptin levels

What are the current recommendations to evaluate to assess weight status

- total body fat (more important than weight) - location of body fat - weight-related medical complications

What is Body Mass Index (BMI)

Preferred height-to-weight standard - linked to body fat content - body fat influences health more than body weight - linked to longevity - easy to assess - does not measure body composition!!

BMI for underweight

<18.5

BMI for healthy weight

18.5-24.9

BMI for overweight

25-29.9

BMI for obesity

>30

Complications with BMI use

- not necessarily appropriate for children, teens, older adults and pregnant or lactating women - those with very high levels of lean tissues or those less than 5’ tall may have inaccurate categorization

How does underwater weighing measure body composition

- body weight is measured under water and in air - formula accounts for differences in densities of fat and lean tissue - very accurate **body fat weights less under water

How is body composition measured with the air displacement method

Determines body volume by measuring the volume of air displaces when a person sits in a sealed chamber for a few minutes (BodPod) - accurate alternative to underwater weighing

How is skinfold thickness used to measure body composition

- measure fat layer directly under skin at multiple sites - accuracy - can be good; dependent on trained technician - commonly used because it is cheap

How is bioelectrical impedance used to measure body composition

- electrical current sent through body - takes <5 minutes - based on idea that fat resists the flow of electricity more than lean tissue - degree of resistance determines body fatness

What is the best method to measure body composition

DXA

How is DXA used to measure body composition

- most accurate, very expensive, not widely available - body fat, fat-free soft tissue, and bone minerals assessed

What is a healthy weight considered

- a body weight that does not increase risk of developing weight-related health problems or diseases - a range that depends on gender, height and muscle mass

What is the waist circumference related to android (abdominal) obesity

Males: >40 inches Females: >35 inches - more common in males, those with high glycemic diets, high alcohol consumption and smokers - related to: CVD, Hypertension, T2DM