Midterm Flashcards
1 Kcal = ? KJ
4.184 KJ
What is an Atwater Factor?
Atwater factors calculate the amount of energy in food available to humans.
Atwater factor for CHO?
4 kcals
Atwater factor for FAT?
9 kcals
Atwater factor for PRO?
4 kcals
Atwater factor for Ethanol?
7 kcals
Why do CHOs differ in their digestibility?
Fibres are either undigestible (insoluble) or only partially digestible (soluble).
How is energy lost from PRO?
When nitrogen is excreted in urea, some combustible H is lost as well.
What is the hierarchy of oxidation?
The order in which macronutrients are consumed:
- Ethanol
- Carbohydrates and Proteins
- Fats
What is autoregulation?
The ability to change macronutrient expenditure in response to different intakes to keep stores stable.
What are the three components of energy expenditure?
RMR, TEF, EEA
What micronutrient drives fuel selection?
CHO
How does energy expenditure change over a lifespan?
From childhood to early adulthood, energy expenditure increases. After this point, energy expenditure generally decreases with age. It is important to note that individuals of the same age may have very different energy expenditures.
Obligatory thermogenisis
Then energy required for (and heat generated by) digesting, absorbing, and metabolizing nutrients
Facultative thermogenesis
Specialized pathways for creating heat to maintain body temperature.
Brown fat metabolism and shivering are forms of…
Facultative thermogenesis
When weight is lost and then regained, what happens to RMR?
RMR drops significantly with weight loss, and when weight is regained it remains depressed from starting levels.
What percentage of DIT is obligatory?
50-75%
Explain the issues with set-point theory
Set-point theory fails to explain why the population is seeing its set-points rise. It also fails to account for why after periods of severe fasting and subsequent refeeding we do not see a return to pre-fast RMR.
Explain the issue with settling point theory.
Settling point theory does not take into account the biological regulation of weight.
Define hunger
Sensations that promote food consumption
Define satiation
Sensations of fullness that occur during a meal and control cessation of eating.
Define satiety
sensations that determine intermeal periods of fasting.
Define orexigenic
Having a stimulating effect on appetite.
Anorexigenic
Causing loss of appetite
Where is leptin secreted?
From adipose tissue
The effect of leptin is…
Decreased food intake and weight loss
How does leptin interact with obesity?
Obese individuals have generally developed a resistance to leptin.
Where is insulin secreted?
beta-cells in the pancreas
What triggers insulin secretion?
Increased glucose load
What are the effects of insulin?
Insulin reduces appetite and encourages EE.
Where is ghrelin secreted?
The stomach
What is the effect of ghrelin?
Ghrelin stimulates growth hormone and increases food intake.
Ghrelin levels rise in ____ state and fall in ___state.
Fasted & Fed
Where is PYY secreted?
The small and large intestine.
PYY increases when?
After feeding.
PYY leads to ___?
Reduced food intake.
GLP-1 ____ feeding.
Inhibits.
GLP-1 is co-secreted with what other peptide?
PYY
CCK’s two effects are?
Decreasing food intake and stimulating fat digestion.
CCK is secreted where?
small intestine.
Diagnostic criteria for diabetes
fasting plasma glucose >7mmol/L, A1C > 6.5%, 2hPG tolerance test > 11.1mmol/L, random plasma glucose > 11.1mmol/L
Diagnostic criteria for prediabetes
FPG 6.1-6.9 mmol/L, A1C 6-6.4%, 2hPG 7.8-11 mmol/L
Primary vs secondary hypertension
Primary hypertension is hypertension with no obvious underlying cause (about 90%), secondary hypertension is hypertension as a result of some other condition.
Adiponectin (secretion and effects)
Secreted by adipocytes. Concentration of adiponectin is inversely relates to %body fat. It increases insulin sensitivity.
Lipid profile of obesity
Increased triglycerides (mostly VLDL-C and chylomicron), Decreased HDL-C, and smaller LDL particles.
Ectopic fat
Fat “spilling over” from adipocytes into other organs and causing organ displacement.
How are sleep and appetite related?
With less sleep, appetite for all foods (especially sweet, salty, and starchy foods) increases.
How does sleep effect ghrelin and leptin?
Less sleep increases ghrelin, and decreases leptin.
Cushing’s syndrome
An excess of cortisol, altering lipid accumulation and mobilization, resulting in increased abdominal adiposity (among other outcomes)
Effect of chronic stress on weight.
About 40% of people gain weight, 20% remain weight stable, and 40% lose weight.
5 levels of body compartmentalization
Atomic Molecular Cellular Organ-tissue Whole body
What is the difference between LST and FFM? AT what level do these compartments exist?
LST skeletal muscle and residual mass (organs). FFM includes LST and bone minerals. Exists at the molecular level.
What is the obesity paradox?
The obesity paradox is the way that obesity confounds the relationship between low muscle mass and survival when only BMI is considered. When only BMI is measured, obese people seem to have better survival, but when muscle mass is taken into account, obesity has no protective effect.
How does ageing effect body composition?
After the age of 20, fat mass increases while lean mass declines.
How much does muscle mass decrease per decade between the ages of 40 and 70?
8%
4 main body comp abnormalities
Osteopenia, Obesity, Sarcopenia, Sarcopenic obesity
Why do older adults need more protein intake?
Older adults experience less MPS and require more intake to balance MPB.
How do losing and gaining muscle mass compare?
Muscle mass is lost much quicker (1.5kg in 1.5 weeks) than it is gained (.6kg in 12 weeks), especially in older adults.
Impacts of loss of muscle mass in addition to locomotion and ADLs.
Decreased immunity, risk of pneumonia, slower wound healing.
List some clinical impacts of low MM.
Poorer QoL, longer time in hospital, more post-op complications, greater toxicity, faster progressing tumors, physical impairment.
What 4 elements make up 95% of the human body?
Carbon, Hydrogen, Oxygen, and Nitrogen.
5 components of the molecular level of body comp
Water, Lipids, Protein, Carbohydrates, Minerals
What is the variability in error for most equations that predict FM/FFM from anthropometry?
3-11%
What is impedance?
The conductivity of the body (how much opposition to electrical current is in the tissue)
How does impedance compare between adipose tissue and skeletal muscle?
Muscle has more water, making it a better conductor and offering less impedance.
How do “sick” cell membranes effect phase angle?
Sick cell membranes do not create as much delay in current transmission. More sick cell membranes result in smaller phase angle between the current going through the intracellular and extracellular pathways.
BIA predictive equations need to be specific to two things…
Population and device
4 Factors contributing to BIA reliability
Subject related
Technician related
Equipment related
Environment Related
What is one big benefit of CT imaging?
CT imaging provides information on muscle quality (invasion of fat)
What is the ideal level for CT imaging site to be used to predict total body composition.
L3
