QUESTIONS AND ANSWERS DETAILED & ELABORATED
FULLY SOLVED
Explain how energy balance is related to body weight
Energy consumption matches energy expenditure. Calories in = calories out, body weight
remains constant
Describe what it means to be in energy balance, negative energy balance, and
positive energy balance.
Energy balance: calories in = calories out, body weight remains constant
Positive: Calories in > calories out, body weight increases
Negative: Calories in < calories out, body weight decreases
What happens to excess calories when we eat more energy than we expend?
Those calories get stored as glycogen or fat
How can dietary carbohydrate and protein be stored as fat? Is this preferred to
storing dietary fat?
Dietary fat can be monounsaturated and better for you than fat from stored carbs and
protein
When we are in a calorie deficit, how do we meet our energy needs and maintain
blood glucose?
By breaking down fat and glycogen
What are the components that make up total energy expenditure?
- Basal metabolism
- Physical activity
- Thermic effect of food
- Adaptive thermogenesis
What is the thermic effect of food?
The energy it costs to process and digest food
,What contributes the most to TEE in a sedentary person?
Basal metabolism/Resting metabolic rate
What component is most variable between individuals?
Physical activity
Name 3 variables that can increase basal metabolic rate.
Greater body size, greater amount of lean muscle, being a man
Name 3 variables that can decrease basal metabolic rate.
Getting older, living in cold areas, being a woman
Describe three methods for measuring energy expenditure.
Direct and indirect calorimetry, doubly-labeled water
Define direct calorimetry
The heat given off when placed in a chamber, expensive and impractical
Define indirect calorimetry
Oxygen use and CO2 production
Define doubly-labeled water
ingest isotopes of oxygen and hydrogen, can measure TEE for up to 2 weeks
What is EER and what variables are used in its calculation (including gender)?
Estimated Energy Requirements, estimated using height, weight, age, gender, physical
activity
What changes in the U.S. environment and lifestyle have contributed to the obesity
epidemic?
- Changes in lifestyle (becoming more sedentary)
- Food is plentiful
- Portion sizes are becoming bigger
How do you calculate BMI and why is it commonly used to assess body weight?
(weight in kg)/((height in meters)^2)
What is a healthy BMI range?
,18.5-24.9
What is a major limitation of using BMI to classify an individual as overweight/obese?
Being muscular can make you register as being overweight or obese
Explain why weight loss might be recommended for one overweight individual, but
not for another of the same BMI.
Depends on body composition-- amount of fat vs. muscle, etc.
How does the distribution of body fat affect the risks of excess body fat?
Visceral (waist) fat poses greater health risks. "Apple-shaped" obesity/beer belly
Describe the differences between "android" and "gynoid" body shapes.
Android is "apple-shaped," gynoid is "pear-shaped"
Describe 3 methods for determining body composition.
- Bioelectric impedance analysis
- Skinfold thickness
- Underwater weighing
Define bioelectric impedance analysis
An individual's resistance to painless, low-energy electrical current, lean tissue is more
conductive
Define the skinfold thickness method
Thickness of pinched skin an estimate of fat under skin
Define the radiologic methods
DXA = dual-energy x-ray absorptiometry. 2 x-rays used to determine bone, fat, and lean
mass, can assess visceral fat
Explain one short-term mechanism that can drive you to eat a meal and one that
makes you stop eating when you have eaten enough at a meal.
Ghrelin increases intake, CCK decreases intake
Discuss the role of leptin in regulating body weight.
Leptin decreases intake and increases energy expenditure, obese people become resistant
to leptin
, What is the best approach to weight management? Why?
Steadily and slowly to ensure you're really losing fat and not just water weight
For a healthy weight loss, how much weight loss and at what rate is recommended?
5-15% of body weight, 0.5-2lbs/week
Name the water-soluble vitamins.
B and C
Where are water-soluble vitamins found in our diet?
Mainly through fortification and enrichment
Describe the difference between fortification and enrichment.
Fortification = adding nutrients to food during processing
Enrichment = adding nutrients back to food that were lost during processing
Describe, in general, how water-soluble vitamins are absorbed, transported, stored,
and excreted.
No long-term storage, must be regularly consumed in diet, readily excreted in urine
Describe the coenzyme functions of five vitamins.
Coenzymes are usually B vitamins, that help carry/transport molecules to facilitate reactions
- Vitamin C: antioxidant: neutralizes free radicals produced from oxygen so they can no
longer damage molecules such as DNA.
- Thaimin Pyrophosphate: active coenzyme form of thyamin found in cell: assist in energy
production, production of ribose, health of nervous system
- Riboflavin: FAD, coenzyme in the citric acid cycle and electron transport chain
- Niacin: NAD and NADP: coenzymes: electron carriers in glycolysis and citric acid cycle
- Vitamin B6: Pyridoxine: Pyridoxine phosphate coenzyme that helps amino acids and
carbons molecules be used in the synthesis of ATP, deamination and decarboxylation
reactions, also aids in production of neurotransmitters from amino acids
- Vitamin B12: coenzyme involved in converting folate to an active form to be used for DNA
synthesis
What B-vitamins affect homocysteine levels and why is this important?
Folate, vitamin B6, and vitamin B12 play key roles in converting homocysteine into
methionine. Elevated levels of homocysteine contribute to artery-clogging.