Energy Metabolism Flashcards
What does 1kcal convert to in joules?
4.184kJ = 1kcal
Wha is the difference between gross energy and metabolisable energy
GE is the complete energy contents of food when measure the heat energy released from combusted food to CO2 and H20
ME is the energy we consume from foods in the diet (i.e. GE - energy losses through incomplete digestion and energy lost in urine and sweat via urea / incomplete breakdown of proteins)
What does the kcal represent on food labels?
Metabolisable Energy
Atwater factor for fat?
37kJ/g (9kcal)
Atwater factor for NSPs?
8kJ/g (2kcal)
Atwater factor for monosaccarhides?
16kJ/g (4kcal)
Atwater factor for protein?
17kJ/g (4kcal)
Alcohol atwater factors?
29kJ/g (7kcal)
Give 2 of the 3 major functions of ATP
Drives metabolic reactions that do not occur naturally
Transports substances across membranes (particularly against concentration gradients)
Mechanical work (e.g. skeletal muscle contraction)
What is negative energy balance?
When energy in < energy expended -> i.e. weight loss
What is positive energy balance?
When energy in > energy expended -> i.e. weight gain
Name 3 components of energy expenditure?
BMR / RMR
PA
Thermic effect of food
What is the biggest contributor to energy expenditure in the normal person?
BMR
What is the most variable contributor to energy expenditure?
Physical activity
What is the different between BMR and RMR
RMR is when the strict conditions of BMR are not met and unable to turn of the sympathetic nervous system
What are some of the strict conditions of BMR to be true
awake, resting (lying down), 12 hours after eating, thermal neutrality
What is total energy expenditure?
A multiple of BMR based on PAL
Name 4 key influencers of EE that isn’t PA or BMR
Hormone Status Smoking (raises RMR) Age Body Size (weight>height) Body composition Illness Ambience of temperature
How does illness impact EE?
Normally there is an overall reduction in TEE due to reduced lean body weight, fat mass and PA
There is usually an increase in BMR but this is overcompensated by the lack of PA
What are dietary reference values?
Quantitative guidelines estimated for the population to prevent macro & micro nutrient deficiencies
What are dietary goals?
Quantitative national targets for macro and micro nutrients aimed to prevent long-term conditions
What are dietary guidelines?
Broad targets (both quant and qual) to promote nutritional wellbeing
How is BMI utilised generically?
Allows for assessing body weight in context of associated risk of comorbidities
What is the BMI ranges?
<18.5 U/W 18.5-24.9 N 25.0-29.9 O/W 30-34.9 O1 35-39.9 O2 40.0+ O3
