Metabolism of Weight loss and Adaptations

Question 1

at rest which organs have the greatest % energy expenditure

Answer 1

brain, liver, skeletal muscle

Question 2

fuels in a 75-kg man

Answer 2

adipose - 110,000
protein - 25,000 other + 25,000 muscle

carb- 2,000 muscle glycogen
liver glycogen - 400
free glucose - 80

Question 3

weight of using 100 kcal of glycogen, protein and adipose tissue (explain the differences)

Answer 3

The main principle here is that glycogen is hydrophilic and therefore when 100kcal glycogen is spent, water is also lost ( so on the scale it will look like 100g is lost) whereas when 100kcal of adipose is used, 10 g will be lost- bc no water weight is lost (where does the water go?)

Question 4

what are the 3 phases of blood glucose curve

Answer 4

uptake slope (1 hour), decay slope (1.5-3 hours) and steady phase (34 hours after)

Question 5

lower insulin: glucagon is going to trigger?

Answer 5

steady phase in which increased glycogenolysis and gluconeogenesis

Question 6

why do TG take longer to increase than glucose after a mixed meal ?

Answer 6

must be packed into CM, enter lymphatic system, give off TG into tissues, go to liver, repacked as VLDL- whereas glucose absorbed right into bloodstream from the gut

Question 7

difference between FFA and TG response after a meal

Answer 7

TG slowly increase from the meal, FFA raise from lipolysis during higher glucagon and less insulin, when FA need to be used for gluconeogenesis ( they are NOT from meal )

Question 8

why does glycerol decrease after a meal

Answer 8

bc lipolysis is decreased in response to insulin

• same kinda thing as FFA, we do not need gluconeogenesis with high insulin
• we see a slow increase after glycogen in excreted and insulin is lowered which will induce lipolysis

Question 9

what happens to total amino acids after a meal

Answer 9

they are going to increase as they get transported into the blood, then insulin has a profound impact on the uptake of AA into tissues which will prompt protein synthesis, later once glucagon is secreted, and insulin is lowered, the proteolysis is no lower restricted and so AA would increase later on - gluconeogenesis

Question 10

what happens to urea nitrogen after a meal

Answer 10

it will decrease, this is because the increase in amino acids result in protein synthesis and not the breakdown. may not nessasarily be a positive N balance bu the influx of aa will at least create a zero N balance
- later we see it may increase as proteolysis is induced

Question 11

why do pre-diabetic/insulin resistance lead to hypoglycaemia

Answer 11

insulin resistance means insulin is still excreted in large amounts, just the cells are unresponsive. Therefore there is dysregulation of the negative feedback mechanisms, where the excess insulin secretion will promote smaller amounts of glucagon. so now less gluconeogenesis, glycogenolysis and lower blood glucose levels

Question 12

is there such thing as glycogen resistance

Answer 12

yes

Question 13

what dictates energy storage

Answer 13

insulin: glucagon storage

Question 14

what causes fat storage

Answer 14

excess carbs + excess fat ( excess energy causes fat storage - not necessarily a function of high GI foods alone

• what about excess protein ??

Question 15

what are the goals of adapting to fasting?

Answer 15

• reduce LBM breakdown ( spare protien)
• meet energy needs (REE will lower, become more efficient, less movement)
• glucose requirements

Question 16

alanine cycle

Answer 16

pyruvate in muscle turns to alanine, gets transported in blood to liver, turned back to pyruvate–> gluconeogenesis

Question 17

early fasting

Answer 17

2000kcal/24h

• gluconeogenesis
• glycogenolysis
• lipolyis (constant rate )

Question 18

prolonged fasting

Answer 18

decrease EE by 500kcal
- 1500kcal/24 h

• liplysis (constant rate)
• no glycogen
• sparing effect - less gluconeogeneis from proteins - ketone bodies switch to being main fuel
• cori/alanine continues at the same rate

Question 19

prolonged fasting

Answer 19

decrease EE by 500kcal
- 1500kcal/24 h

• lipolysis ( constant rate)
• no glycogen
• sparing effect - less glujconeogeneis from proteins - ketone bodies switch to being main fuel
• cori/alanine continues at the same rate

Question 20

before ketones can be excreted they ned to be?

Answer 20

salted out which involves the loss of NA, K H, orNH4

Question 21

what cation is preferred for ketone excretion

Answer 21

K , which can lead to hypokalemia

Question 22

pro requirement

Answer 22

1. 0 healthy

1. 0-1.2 for elderly adult

Question 23

fluid requirements

Answer 23

100 ml/kg 1st 10
50ml/kg 2nd 10
20ml for ever kg after that

ex. 70 kg man
(10 x 100) + (50 x 10) + (20 x 50) = 2500ml

Question 24

fluid based on energy

Answer 24

1ml/kcal

Question 25

fluid balance based on urine output

Answer 25

urine output + 500mL/d

Question 26

describe the prolonged total fasting weight loss curve

Answer 26

rapid weight loss at the beginning bc glycogen and protein stores are being used - over time switch to fat ( no water, so less weight seen) lipolysis at a steady state

Question 27

why does urea decrease with prolonged starvation and ammonia increase?

Answer 27

more ketone bodies are being excreted in the body , get salted out with ammonia. protein sparing effect, so less catabolism of protein, less proteolysis which means less urea - overall less g of nitrogen are excreted bc less overall breakdown and intake of protein - increase in ammonia also from gluconeogenesis in the kidneys - glutamine into glucose

Question 28

renal consequences of starving

Answer 28

- need normal kidney function - ammonia is toxic so need more water - acid/base balance changes in response to starvation need to be controlled by the kidney

Question 29

describe the main idea behind the N intake, EE and N balance graph

Answer 29

This graph shows that for someone who EI=EE (1.0), as N intake increases, N retention increase and you will reach zero, you can see that it is possible to go into a positive nitrogen balance for a short time but it will eventually balance out to zero as body adjusts. we see that when someone is not meeting energy needs it takes longer for them to reach zero ( if ever) bc so much protein catabolism is taking place ( so much N excretion). in the same sense someone eating above E requirement, can reach a N balance faster ( with less pro intake) so a positive N balance can be seen even with low intake ( less excretion )

Question 30

why in graph with reduction diets was N balance initially negative ?

Answer 30

on a energy restriction diet, the body was needing to use some protein so excreting a lot of N , and are not able to reach zero until body adjusts ( relies less on protein )

Question 31

describe Forbes equation

Answer 31

relationship between the amount of body fat and the loss of LBM during dieting - with higher body fat initially, we see less LBM loss: total weight - whereas, if low body fat, will have more LBM loss

Question 32

Forbes predictions 1:

Answer 32

during fast, obese individuals will lose less nitrogen ( hence less LBM) than thin ppl

Question 33

Forbes prediction 2:

Answer 33

the fatter the subject the less LBM to Toal weight loss

Question 34

what happens to the cardiovascular system with severe weight loss?

Answer 34

``` less cardio output, HR, BP increased tachycardia ( fast heart beat to compensate for low BP and low BV) ```

Question 35

what happens to the immune system with severe weight loss?

Answer 35

less T-cell function/lympocytes | less cytokines

Question 36

what happens to the renal system with severe weight loss?

Answer 36

acid/base stress on the kidneys

Question 37

what happens to the GI system with severe weight loss?

Answer 37

less lipid absorption- ste-at-orr-hea (fatty stools)

Question 38

what happens to the electrolytes with severe weight loss?

Answer 38

potassium losses - hypokalemia

Question 39

why does steatorrhea occur during starvation?

Answer 39

decrease in villous SA due to atrophy ( gradually decline in effectiveness or vigor due to underuse or neglect ) - bc eating less, using system less - so less lipid absorption

Question 40

why is there potassium loss with severe weight loss?

Answer 40

potassium is the main buffering agents during the excretion of ketoacids - this casues hypokalemia

Question 41

why would we never advise someone with impaired kidney function a severe weight loss diet

Answer 41

acid/base balance changes in response to starvation need to be controlled by the kidney if not properly functioning - build up of keto acids, not properly excreted - toxic acid/base stress on the kidneys

Question 42

refeeding syndrome

Answer 42

metabolic complication associated with nutritional repletion

Question 43

cause of referring syndrome

Answer 43

shift back to glucose instead of ketoacids

Question 44

what does the shift back to glucose cause

Answer 44

rapid fluxes of insulin rapid shift of electrolytes and anions and cations into intracellular space ( think sodium glucose linked transporters that are needed for uptake of glucose into the cells) so when lots of insulin - lots of glucose moving into the cell - lots of anions and cations moving into the cell - this casues sodium and water retention ( anions moving into cell- water following )

Question 45

which anion/cation is the biggest issue during the referring syndrome?

Answer 45

The hallmark biochemical feature of refeeding syndrome is hypophosphatemia, also referred to as refeeding hypophosphatemia (RH). ... The combination of cellular uptake of phosphorus together with depletion of total body stores during starvation causes extracellular hypophosphatemia.

Question 46

symptoms of referring syndrome ( mostly due to hypophosphatemia )

Answer 46

fatigue, weakness, arrhythmia, hemolysis, edema, dizziness, lethargy

Question 47

how fast is onset of referring syndrome

Answer 47

fast ( first day of repletion )

Question 48

what changes physiologically during repletion

Answer 48

ECF expansion - deem from increased Na intake and electrolyte imbalances ( this is why want to limit water and salt intake during referring )

Question 49

ECF expansion

Answer 49

The sodium retention and extracellular fluid expansion together with thiamine deficiency can lead to congestive cardiac failure. excess carbs lead to the retention of sodium and water

Question 50

glycogen synthesis during refeeding

Answer 50

may lower serum Po4 and K concentration

Question 51

increased REE during refeeding

Answer 51

due to the reversal of starvation and LBM rebuilding and thermogenic effects of metabolizing food

Question 52

physiological changes during repletion

Answer 52

1. glycogen synth 2. insuring secretion 3. ECF expansion 4. increased REE

Question 53

steps in refeeding

Answer 53

- normalize fluid balance and electrolytes - PO4, K and Mg with supplements ( seperatee from food) - limit sodium and water intake - mixed diet- aim for 100-150g glucose to stop LB breakdown but start with 25% dose - thaimine supplement protein at 1.5-2 ( but start at 20g/day) - monster

Question 54

why is thiamine so important in refeeding syndrome

Answer 54

cofactor for many anabolism mechanism - for production of ATP

Question 55

PRO for refeeding

Answer 55

start with 20g/day but gradually increase to 1.5-2 g/kg/d

Question 56

glucose for refeeding

Answer 56

aim for 150-200g/d but start with 25% dose

Question 57

important supplements during refeeding

Answer 57

K, PO4, Mg, thiamine

Question 58

physiological changes after diet induced weight loss that lead to increased energy storage

Answer 58

lowered FA oxidation, EE, thyroid hormones, increased cortisol

Question 59

physiological changes after diet induced weight loss that lead to increased food intake

Answer 59

low leptin, PYY, amylin, insulin and raised gherkin and altered neural activity

Question 60

how much does REE decrease per kg lost

Answer 60

15%

Question 61

what lead to a decrease in EE during weight loss

Answer 61

15% REE less PA decrease in TEF

Question 62

PYY _____ after weight loss

Answer 62

decreased ( it is an anorexigenic hormone that decreases hunger)

Question 63

what did high fat/low carb diet resemble

Answer 63

metabolically similar to "fasting state"

Question 64

describe high Fat vs high carb diet results

Answer 64

more severe weight loss initially with high fat (more water loss?), but net result was only a slight weight difference ( < 1kg)

Question 65

effect of insulin on low fat vs low carb?

Answer 65

no effect- didn't prevent baseline insulin

Question 66

short term effects of keto

Answer 66

halitosis, muscle cramps, headache, weakness, rash,

Question 67

long term effects of keto

Answer 67

``` ketoacidosis ( if illness also) elevated LDL renal stones thiamine def carotene def water sol vitamin def ```