Metabolism of weight loss Flashcards
what are the 3 parts of the body that expends more energy at rest
- brain (20%)
- liver (21%)
- skeletal muscle (22%)
however, skeletal muscle is bigger than the other organs
most energy is stored as
adipose tissue
what is the diff between 100 kcal of glycogen, protein and lipids
glycogen and protein are stored with majority water and adipose tissue is mostly fat
for 100 grams of protein or glycogen - 80% is water. But for 10g of adipose tissue it is almost 10g for fat
in the beginning of weight loss the first thing we lose in glycogen and protein is
water
what is the path of ingested glucose in out body
ingested glucose goes in our liver, and then it is transformed in VLDL to form adipocytes
OR muscle and adipocytes are sensitive to ingested glucose and it can also go to CNS, RBC
describe the blood glucose curve and the hormones or pathways that takes place
- uptake slope
- decay slope
- steady phase
- uptake slope:
insulin release, increase in GI abs, glycolysis, decrease in glycogenolysis and gluconeogenesis - decay slope:
high insulin: high tissue uptake, high glycogenesis
increase in glucagon
- steady phase
decrease in insulin high in glucagon
high glycogenolysis and gluconeogenesis
what is the response to a meal (what increases and decreases)
increase: insulin, glucose, lactate, pyruvate, triglycerides, alanine, total amino acids
decrease: glucagon, free fatty acids, ketoacids, glycerol, urea nitrogen
what is the diff of the blood glucose curve between a person who is insulin resistance and normal
normal: the blood glucose will pick after h and then it will go down
insulin resistance: blood glucose will pick very high one hour after and then it will go extremely down after 4 hours after eating (below normal) which is called reactive hypoglycemia (resistant to insulin and glucagon)
what is reactive hypoglycemia
when the blood glucose level go extremely down normally after 4h after eating. Glucagon resistance
how do people sell fad diet with the carb-insulin model of obesity
they say that carbs have the most effect on insulin therefore it favor energy storage and weight gain. They say that eating food that has a low GI favors weight loss by controlling the amount of carbs and insulin in the food
what causes fat storage
high carb intake and high fat intake cause fat storage and not necessarily GI alone
What are the goals when adapting to fasting
- meet energy needs (for all of our tissue live and survive)
- meet glucose reqt (important to maintain glucose level)
- spare protein (conserve mass)
what is the energy paradox
- the brain needs around 500 kcal of water soluble (glucose) fuels per day
- almost all energy is stored as fatty acids and not glycogen
- fatty acids cannot be converted to glucose
what happens to the fuel flux after 24h of fasting (2000 kcal)
- triglycerides releases fatty acids in the circulation goes to muscle and liver
- muscle send amino acids to the liver
- liver produce glucose that goes into the cori cycle ( goes to the brain, RBC) and it produces ketones
what happens to the fuel flux after prolonged fasting (1500) compared to early fasting
you have less amino acids in the muscle, less glucose goes to the cori cycle. One part becomes urine and less glucose goes to the brain
LOW insulin
What is the glucose utilization from different sources in fasting
- exogenous
- glycogen
- gluconeogenesis
- ketoacids
when glucose stores are depleted what is the other fuel for the brain
ketone bodies
how can ketoacids be secreted
it can be secreted by the lungs and kidney
what are the implications of secreting ketones
because they are acids they need to be buffered with potassium so it leads to hypokalemia
the diff of urinary nitrogen constituents between normal and starvation
normal: a lot of urea, less ammonia
starvation: less urea and more ammonia.
you have less protein coming therefore there is less urea excretion
what is the consequence of starvation in renal
- need normal kidney function
- ammonia is toxic so needs more water for excretion
- acid/base balance changes in response to starvation and it needs to be controlled by the kidneys
what is the relationship between nitrogen intake, energy intake and N balance
with a less nitrogen intake ( protein) you will have a negative nitrogen balance until you reach the reqt by eating more protein
person that has a deficiency will take more protein intake to reach a balance nitrogen balance
what is the difference between 2 groups that have 2 diff nitrogen balance and that want to loose weight
in the beginning the 2 groups drops of nitrogen balance but then the one that eats more protein will reach nitrogen balance and maintain over time the weight and the one that eat not a lot of protein will have a negative nitrogen balance
explain the forbes equation
a graph of lean body mass to change weight by body fat. The more a person is fat the harder it is to change weight
what are the 2 predictions of Forbes equation
- during fast, obese individuals will lose less nitrogen than thin people
- the fatter the subject the less the contribution of LBM to total weight loss on energy-restricted diets
what are the physiological changes to severe weight loss in
cardiovascular and renal
immune function
gastrointestinal function
electrolytes
- cardiovascular and renal:
decrease cardiac output, heart rate, BP
increase tachycardia
increase stress on kidneys (acid/base balance) - immune function
decrease of T cell function/lymphocytes - gastrointestinal function
decrease on lipid absorption
decrease on gastric, pancreatic and blue secretion/production
decrease of villous surface area - electrolytes
potassium losses
what is the refeeding syndrome
refeding a person that has being fasting for a long period of time or that is on a diet for a long period of time
people that are on a diet for a longtime or fatsing what they were used to and what it will change
they were used to keto acids and they will shift to glucose
what should we expect when they shift back to glucose
- rapid fluxes of insulin due to CHO load
- rapid shift of electrolytes and intracellular anions and cations to intracellular space
- sodium and water retention
what is going to be their symptoms when they are back to glucose (refeeding syndrome)
fatigue, lethargy, dizziness, msucle weakness, arrythmia, hemolysis and edema
what are the physiological changes during repletion
ECF expansion : edema from increased Na intake and electrolyte imbalances
Glycogen synthesis lower serum PO4 and K concentrations
Increased REE : lean body mass rebuilding
increased insulin secretion form carb intake : stimulates Nitrogen retention (retention of protein), stimulates cell synthesis, growth, and rehydration
what are the steps in refeeding
- normalize fluid and electrolyte imbalances
use supplementation, limit sodium in the first days - provide a mixed diet at a maintenance energy level
to establish tolerance and avoid refeeding syndromes. Aims 100-150g glucose to stop LBM breakdown + thiamine supplementation - provide protein at 1.5-2g/kg
start with 20g/day to urea cycle enzyme adaptation - monitor serum electrolytes, weight, intake and output
what is the weight loss trajectory
normally you regain some weight but less than you started with
what are some physiological changes after diet induced weight loss
high energy store and high food intake
what are the causes of a high energy store and a high food intake
high energy store : high cortisol, low fat oxidation, low energy expenditure
high food intake: less satiety bc the hormones (leptin, insulin, amylin decrease), and high ghrelin so higher appetite
what are the weight loss countermeasures
lower energy expenditure : REE decrease bc of the metabolic adaptation, decrease in P.A, decrease TEF
and higher appetite: less satiety more hunger bc of the hormonal adaptation (ghrelin increases an PYY decreases)
true or false
obese have a higher REE than lean
true
metabolic adaptation
it is when your body adjust to reducing the REE
explain the biggest loser study after 6 years
they lost a low of weight in the program and after 6 years they went to review their weight. They gained weight compared to when they were in the show but it is less than when they started however, the amount fo calories they are eating is the same as it was during the show meaning there was some metabolic adaptations
Are there some difference in effects of carbs and fat ration in energy expenditure and fat loss
no
which type of macronutrient has the more + influence on weight loss and gain of lean mass and REE and maintain new weight
protein
