Energy Flashcards
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What are the 3 componets of energy expenditure?
- Basal Energy expenditure
- Thermic Effect of Food
- Energy Expenditure of Physical activity
What other factors impact energy expenditure>
Cold adaption, medications, and emotions
Describe what BEE is
The energy needed at complete rest. When you first wake up in the morning
What percentage of total daily expenditure is BEE?
60%
What is the difference between RMR and BEE?
RMR is a bit higher because it includes sedentary activities
Describe TEF
The energy needed for digestion, absorption and storage of food
How much of the daily expenditure is TEF?
5-15%
Describe what EEPA is?
The sum of all physical exercise
What is included in EEPA?
Exercise activity thermogenesis ( planned exercise) and non-exercise activity thermogenesis
What is the direct way of measuring energy expenditure?
You would measure the changes in body temperature (heat production)
Why would you measure body temperature in the direct way of getting energy expenditure?
Due to the inefficiencies of of the body systems, it produces heat which can be measured
What are the indirect ways of measuring energy expenditure?
Oxygen consumption as a marker of heat production and doubly labelled water
Why do we measure oxygen consumption when we are measuring energy expenditure?
Oxygen is a marker of heat production. The body does not store a lot of oxygen (hence us breathing constantly). Most aerobic reactions use oxidative substrates for heat production (energy).
What does a respiratory quotient represent?
CO2 produced / O2 consumed
Explain doubly labelled water as a measure of energy expenditure.
Ingest 2 labelled isotopes 2H2O18, O18 will leave as CO2 and H2O. difference between the 2 isotopes + total water pool. Unlabelled CO2 from oxidized fuel
Do you need to measure TEF, why or why not?
No, because TEF is very similar for everyone
How much variance is there in BEE/RMR?
> 80%
What contributes to the variance in BEE/RMR
Free fat mass and to a lesser degree age and gender
Food restriction results in…
decreased BMR
How would you find PAL
TEE:BEE
What can effect TEF
overeating and undereating
Why is there variance of TEE in people the same size?
80% of BEE is accounted for by body size, so when people are the same size the varience is due to NEAT
What 2 factors account for the variation of NEAT?
Evironmental (egocentric) - My sedentary activities, job transport
Biological (geocentric) - walkways, office fitness, walk clubs
Energy Balance =
Maintence of energy stores
What energy stores are depleted during short term?
Glycogen reserves (24hr) and some fat
What stores are depleted during long term fasting?
Protein and fat catabolism
what factors impact body energy balance
Compostion of tissue mass gained or lost, impact on enerfy expenditure (lean mass vs fat) and intake (type of fuel)
Nutrient and Energy Balance achieved when intake =
body’s rate of oxidation of each macronutrient
What are our afferent signals?
Inputs, peptides, hormones and vagal afferent send signals to the controller CNS
What are our efferent signals?
Outgoing signals from the CNS, they are going to adjust our food intake and energy expenditure in order to keep energy balance
What are the CNS Afferent signals for control of energy
Short term meals and long term storage (adiposity)
How do efferent signals respond ?
Hunger, energy expenditure, energy portioning, growth and reproduction
What is the short term physiological response (general) to food intake?
- Gut signal - stretch receptor and chemical (peptides from GI tract) —> act with GI peptides to reduce meal size and lengthen inter-meal satiety
- Meal related CNS signals (quality and quantity of the meal) different hormones released which the hypothalamus is sensitive to based on blood concentrations of aa, glucose, fatty acids. Negative feedback
- Information collected by brain stem ( Nucleus of solitary tract), sent to hypothalamus with other meal signals
If we have so many hormones to suppress eating, why do we still over eat?
Override the signals, overeating
What are the long term adiposity signals?
Lepton is secreted proportionally to the adipocytes, to decrease hunger and increase energy expenditure
Insulin secreted by the beta cells of the pancreas, so increase in food availability = more insulin = reduced appetite
Explain insulin resistance
When more insulin is released for the same effect on the body
How does the CNS converge the long term and short term signalling?
• Meal-derived signals(short term) collated by Nucleus of the Solitary Tract (Brain-stem) NTS.
• Short and long-term signals collated by paraventricular nucleus (PVN) located in the ventromedial hypothalamus (VMH)
• Lateral Hypothalamus (LH);stimulates feeding (ghrelin)
• Arcuate Nucleus(Arc)in hypothalamus converges adiposity signals (eg insulin and leptin receptors)
What is the regulation of food intake (via leptin and insulin) during energy surplus?
Increased leptin and insulin = + POMC (in arc) -> increased alphaMSH + decreased AgPR—> MC4T -> + anorexgenic
= decreased NPY and AGRP —> - Y1R + Y5R —> - orexgenic
= decreased food intake and increased energy expenditure
What is the pathway for decreased food intake via leptin and insulin?
Decreased leptin and insulin = - POMC (in arc) -> decrease alphaMSH + increased AgPR—> MC4T -> - anorexgenic
= increased NPY and AGRP —> + Y1R + Y5R —> + orexgenic
= increased food intake and decreased energy expenditure
Explain metabolic syndrome?
Aka syndrome x or insulin resistance. Describes individuals that are more than just obese and have increased risk of CVD and diabetes
How much heat is lost due to biochemical ineffiencies of converting to ATP?
60%
How are water soluble nutrients transported?
enter directly into capillaries, feeding the portal vein (directly to liver)
How are lipid souble transported
transported via chylomicrons into lymphatics
* CMsvtoovlarge to enter blood capillaries \ enter lymphatic capillaries via fenestrations of lacteals; eventually enter blood circulation via lymphatic vessels (thoracic duct)
What has a RQ of 1
glucose
what is the consequence when ingestion is greated than oxiadation of macronutrients
increase in energy stores
What is the hierachy of oxidation
alcohol > protein > glucose > fats
What hormone signals a hunger response
Ghrelin
