week 1 LOs

Question 1

List components of energy balance equation (including those of energy expenditure)

Answer 1

• Energy in = Energy out
• total energy expenditure (TEE) = resting metabolic rate (RMR) + thermic effect of food (TEF) + Energy expended in Physical activity (EEPA)
• non-exercise activity thermogenesis (NEAT) also included in EEPA)
• Intake is food but often poorly reported–most people underestimate

Question 2

accuracy of measuring energy intake

Answer 2

people often under-report food intake, especially if overweight
- if stable weight can use energy intake = TEE (use doubly labeled water)

Question 3

Measure RMR

Answer 3

use indirect calorimetry – measures respiratory gas composition/flow rates to estimate O2 consumed/CO2 produced
- can also ESTIMATE using formulae (age, sex, height, weight; lean body mass makes more accurate)

Question 4

Measure TEF

Answer 4

• indirect calorimetry by determining increment of energy expenditure above RMR following ingestion of defined test meal

Question 5

Measure EEPA

Answer 5

• most variable
• measure most accurately with doubly labeled water to measure O2 consumption over weeks–subtract RMR and TEF from TEE to get EEPA
• can estimate with quesitonnaires
• measure activity directly with pedometers, accelerometers, GPS based activity monitors

Question 6

Pool size of stored fat, carb, protein

Answer 6

• fat is largest store. about 120,000 kcal in normal weight individual
• carb stores about 2000 kcal (glycogen in muscle-400g and liver-100g)
• protein– no readily accessible storage. Can break down muscle into amino acids if persistently in negative energy balance.

Question 7

Glucose structure

Answer 7

6 Carbon chain– made into a hexagon with oxygen as one corner

Question 8

Fatty acid structure

Answer 8

methyl group on one end, acid group (COOH) on other end with a hydrocarbon chain in middle)

Question 9

amino acid structure

Answer 9

amine group on one end, carboxylic acid on other end. In middle lies a carbon with a variable side chain

Question 10

Hierarchy of fuels for oxidation

Answer 10

Protein oxidized first since no stores. If in protein balance, carbs preferentially oxidized then fat since better storage capacity for fat

Question 11

What is the result of the hierarchy of fuel oxidation

Answer 11

People with positive energy balance will tend to accumulate body fat. Those with negative energy balance glycogen and protein in muscle broken down– eventually lack essential amino acids, essential fatty acids, and micronutrients that become depleted when poor energy intake

Question 12

8 main biochemical pathways in carb, fat, amino acid metabolism

Answer 12

• Glycolysis
• TCA cycle
• Electron transport
• Gluconeogenesis
• Glycogen storage/breakdown
• Pentose Phosphage pathway (hexose monophosphate shunt)
• Triacylglycerol Synthesis (ne novo lipogenesis)
• Triacylglycerol degradation/Beta-oxidation/Ketogenesis
• Urea cycle

Question 13

general layout of main metabolic pathways for carbohydrate, fat, and amino acids

Answer 13

Carb:

• glycolysis
• TCA cycle
• Electron Transport
• Gluconeogenesis
• Glycogen synthesis/degradation
• Pentose Phosphate pathway

Fat:

• Triacylglycerol Synthesis (de novo synthesis)
• Triacylglycerol degradation, beta-oxidation, ketogenesis

Protein
- Urea cycle

Question 14

general function of biochemical pathways

Answer 14

● Macro level: nutrients moving between organ systems
● Micro level: processes within cells
● When the body is in positive energy balance following the consumption of a meal the primary task for the metabolic pathways is to assimilate the ingested nutrients and fill storage pools such as triglyceride in adipose tissue or glycogen in muscle. This process is coordinated by hormones.
● During a fasting state, stored nutrients are broken down into their component building blocks (glucose, fatty acids and amino acids) and these building blocks are then moved to these energy requiring tissues to meet their energy needs.