Required Readings - Midterm Flashcards
Average weight loss maintained after 4.5 years upon completing a weight loss program?
3 kgs
Define successful weight loss (According to the study: defence of body weight)
Intentionally losing at least 10% of initial weight and keeping it off for at least one year
Where is the homeostatic regulation of body weight regulated?
The arucuate (ARC) nucleus Hypothalamus - involved in the control of food intake.
What protects us from weight loss? Is it the same for weight gain?
Regulation of signals from the hypothalamus - not as vigorously regulated for weight gain (easier to gain weight)
What does the evolutionary protection of weight loss mean?
It is difficult to lose weight
What two neuro-peptides within the ARC responsible for stimulating food intake?
1) Neuropeptide Y
2) Agouti-related peptide
What neuro-peptide within the ARC is responsible to suppress food intake?
POMC
Anorexigenic neuropeptides from the pancreas?
- Amylin
- Insulin
- PP
Anorexigenic neuropeptides from the adipocytes?
Leptin
Anorexigenic neuropeptides from the GI tract?
CCK
GLP-1
PYY
What is the reward circuit?
Hedonic pathway
What is the hedonic pathway? Can it override the homeostatic system?
Relates to the sight, smell and taste of food along with emotional and social factors. Can override homeostatic system, causing us to gain weight
Name the physiological adaptations to diet-induced weight loss (EFTC)
- Decr. Energy expenditure
- Decr. Fat oxidation
- Decr, thyroid homrones
- Incr. cortisol
What does EFTC favour
Increase in energy storage
Name the physiological changes to diet-induced weight loss (PAIL-GG-A)
- decr. PPY
- decr. Amylin
- decr. Insulin
- decr. Leptin
- incr. GIP
- incr. Grehlin
- incr. Appetite
What doe PAIL-GG-A favour?
Work together to increased food intake
What physiological factor may reduce food intake after diet-induced weight-loss?
An increase in pancreatic polypeptide
Diet-induced weight loss of 10% of BW leads to a reduction in TEE by ___ due to changes in body mass and composition.
15%
Weight stable formerly obese patients have lower fasting / 24 hour rates of ___ oxidation
fat
What does a lower rate of fat oxidation cause?
May lead to a positive fat balance and negative carbohydrate balance
Low fat oxidation (burning carbohydrate instead of fat) is associated with what?
Weight gain
How can we increase fat oxidation rate?
Exercise, which may cause slow-twitch muscle fibres to derive more energy from fat, compared to fast-twitch which rely on glycogen stores.
Obesity is associated with a resting ____ overactivity
sympathetic nervous system
What does overactive SNS cause?
down-regulation/desensitization to adrenoreceptors
-impair EE, TEF and fat oxidation
___ hormones play an important role in energy expenditure
Thyroid
Increase is TSH increase/decrease REE
Increase
How does diet-induced weight loss impact thyroid hormones?
Energy restriction suppresses the hypothalamic-pituitary axis, impairing secretions of thyroid hormones.
Following reduction of food intake, higher amounts of ___ is secreted
Cortisol
Wha are the effects of increased cortisol?
- Suppression of cortisol
- Weight gain
- Central adiposity
How does leptin decease food intake?
Reduces expression of AgRP and NPY (orexigenic) and stimulates POMC (anorexigenic)
Leptin secretion is proportional to ___
fat mass
Leptin administered to people at baseline weight had ___ effect on BW and appetite
little
Leptin administered to people during an energy deficit ___ appetite
decreases
In weight-stable, weight-reduced subjects, leptin “replacement” to pre-weight loss levels___ many fo the adaptive physiological changes to diet-induced weight-loss.
reverses
What neuropeptides INCREASE during diet-induced weight loss and INCREASE food intake?
Grehlin
GIP