Endocrine Weight Loss Endocrine System 3 — Questions and Answers
Question 1: Which of the following best explains why caloric restriction alone often fails to sustain long-term weight loss?
- Gut microbiome changes overwhelm the deficit
- Compensatory rise in ghrelin and fall in leptin increase hunger (Correct answer)
- Insulin secretion permanently increases
- Cortisol drops too low to maintain energy
Correct answer: Compensatory rise in ghrelin and fall in leptin increase hunger
Caloric restriction raises ghrelin and lowers leptin and PYY, creating a hormonal environment that strongly drives appetite and slows metabolism.
Question 2: Insulin resistance causes weight gain primarily by:
- Increasing thyroid hormone clearance
- Driving excessive glucagon secretion
- Promoting fat storage and impairing lipolysis (Correct answer)
- Suppressing leptin production
Correct answer: Promoting fat storage and impairing lipolysis
High insulin levels signal adipocytes to take up glucose and fatty acids for storage while simultaneously inhibiting fat breakdown.
Question 3: Which hormone released by the pancreas counteracts insulin by raising blood glucose and promoting lipolysis?
- Somatostatin
- Glucagon (Correct answer)
- Amylin
- Pancreatic polypeptide
Correct answer: Glucagon
Glucagon, secreted by pancreatic alpha cells during fasting, stimulates hepatic glucose release and fat breakdown.
Question 4: A patient on long-term glucocorticoid therapy develops a 'buffalo hump' and central obesity. This is an example of:
- Primary hypothyroidism causing fat redistribution
- Exogenous Cushing's syndrome from chronic cortisol excess (Correct answer)
- Leptin resistance from sustained hyperleptinemia
- Growth hormone excess causing lipodystrophy
Correct answer: Exogenous Cushing's syndrome from chronic cortisol excess
Chronic exogenous glucocorticoid use mimics Cushing's syndrome, redistributing fat to the neck and abdomen.
Question 5: Which incretin hormone, released after eating, stimulates insulin secretion and is the basis for GLP-1 receptor agonist weight loss drugs?
- Cholecystokinin (CCK)
- Glucagon-like peptide-1 (GLP-1) (Correct answer)
- Vasoactive intestinal peptide (VIP)
- Secretin
Correct answer: Glucagon-like peptide-1 (GLP-1)
GLP-1 is released from intestinal L-cells postprandially and enhances glucose-dependent insulin secretion while also reducing appetite.
Question 6: The set-point theory of body weight regulation suggests that after weight loss, the body defends its prior weight mainly through:
- Permanent changes in muscle fiber type
- Neuroendocrine adaptations that reduce metabolism and increase hunger (Correct answer)
- Increased insulin sensitivity reducing energy use
- Accelerated gastric emptying raising caloric absorption
Correct answer: Neuroendocrine adaptations that reduce metabolism and increase hunger
After weight loss, metabolic rate drops more than expected for the new body size and appetite hormones shift to promote regain.
Question 7: Which thyroid hormone is considered the metabolically active form that directly regulates cellular energy use?
- Thyroxine (T4)
- Reverse T3 (rT3)
- Triiodothyronine (T3) (Correct answer)
- Thyroid-stimulating hormone (TSH)
Correct answer: Triiodothyronine (T3)
T3 binds nuclear receptors in cells and upregulates genes involved in basal metabolic rate, thermogenesis, and mitochondrial function.
Endocrine Weight Loss Endocrine System 3
Which of the following best explains why caloric restriction alone often fails to sustain long-term weight loss?