CBC Obesity Science and Etiology Questions and Answers — Questions and Answers
Question 1: Which of the following accurately describes the primary role of the hormone ghrelin in the regulation of body weight?
- It is released by adipose tissue and signals satiety to the brain.
- It is secreted by the stomach and stimulates appetite. (Correct answer)
- It is produced by the pancreas to regulate blood glucose after a meal.
- It is secreted by the adrenal glands in response to stress, promoting fat storage.
Correct answer: It is secreted by the stomach and stimulates appetite.
Ghrelin is commonly known as the 'hunger hormone'. It is primarily produced and secreted by the stomach when it is empty. It then travels to the brain, specifically the hypothalamus, where it acts to stimulate appetite and food intake. In contrast, leptin is the hormone released by adipose (fat) tissue to signal satiety, insulin is produced by the pancreas, and cortisol is the primary stress hormone from the adrenal glands.
Question 2: A client expresses frustration, stating, 'No matter how much I diet and lose weight, my body seems to fight me to get back to my usual weight.' This experience is best explained by which of the following concepts in obesity science?
- The thrifty gene hypothesis.
- The body weight set-point theory. (Correct answer)
- The glucostatic theory.
- The obesogenic environment theory.
Correct answer: The body weight set-point theory.
The body weight set-point theory posits that the body has a predetermined weight range that it actively defends. When weight drops below this set point, the body initiates compensatory physiological mechanisms, such as increasing appetite and decreasing metabolic rate, to promote a return to the set-point weight. This explains the feeling of the body 'fighting back' against weight loss efforts. The other options are related but less specific to this phenomenon.
Question 3: A counselor is working with a community to identify factors contributing to high obesity rates. Which of the following is the BEST example of a macro-level factor within the 'obesogenic environment'?
- The widespread availability and low cost of ultra-processed, high-calorie foods. (Correct answer)
- A family's tendency to eat meals while watching television.
- An individual's genetic predisposition to store fat.
- A person's lack of motivation to engage in regular physical activity.
Correct answer: The widespread availability and low cost of ultra-processed, high-calorie foods.
The 'obesogenic environment' refers to external, systemic factors that promote weight gain. The widespread availability and low cost of unhealthy foods is a macro-level (large-scale, societal) factor that influences the entire community. The other options represent a micro-level family habit, an individual genetic factor, and a personal psychological factor, not macro-level environmental conditions.
Question 4: From a metabolic standpoint, what is the primary functional difference between brown adipose tissue (BAT) and white adipose tissue (WAT)?
- BAT primarily stores energy as triglycerides, while WAT is specialized for thermogenesis.
- WAT is the primary tissue affected by insulin resistance, while BAT is not.
- WAT secretes the hormone ghrelin, while BAT secretes leptin.
- WAT primarily stores energy, while BAT is specialized to burn calories to produce heat. (Correct answer)
Correct answer: WAT primarily stores energy, while BAT is specialized to burn calories to produce heat.
White adipose tissue (WAT) is the body's main energy storage depot, storing excess energy as large triglyceride droplets. In contrast, brown adipose tissue (BAT) is metabolically active, containing many mitochondria that allow it to burn calories and dissipate energy as heat, a process called non-shivering thermogenesis. Therefore, their functions are essentially antagonistic: WAT stores energy, and BAT expends it.
Question 5: The concept of epigenetics in obesity etiology suggests which of the following?
- Obesity is solely determined by a single 'obesity gene' that is either active or inactive.
- Environmental factors can modify gene expression without changing the DNA sequence, influencing obesity risk. (Correct answer)
- An individual's DNA sequence is permanently altered by their parents' lifestyle choices.
- Genetic factors have no significant influence on an individual's susceptibility to weight gain.
Correct answer: Environmental factors can modify gene expression without changing the DNA sequence, influencing obesity risk.
Epigenetics refers to heritable changes in gene function that do not involve changes to the underlying DNA sequence. In the context of obesity, environmental factors (like diet or stress) can cause epigenetic modifications (such as DNA methylation) that turn genes 'on' or 'off', thereby altering an individual's lifelong susceptibility to weight gain without changing their genetic code.
Question 6: Research into the etiology of obesity has increasingly focused on the gut microbiome. Which of the following is a proposed mechanism by which gut microbiota can influence body weight?
- By altering the efficiency of energy extraction from food and influencing appetite-regulating hormones. (Correct answer)
- By directly controlling the secretion of thyroid hormones to regulate metabolism.
- By exclusively producing leptin, the body's primary satiety hormone.
- By altering the genetic code of intestinal cells to prevent all fat absorption.
Correct answer: By altering the efficiency of energy extraction from food and influencing appetite-regulating hormones.
The gut microbiome can influence body weight through several mechanisms. These include altering the efficiency of calorie extraction from food, producing short-chain fatty acids that influence metabolism, and modulating the secretion of gut hormones (like GLP-1 and PYY) that affect appetite and satiety. This complex interplay can impact energy balance and fat storage.
CBC Obesity Science and Etiology Questions and Answers
Which of the following accurately describes the primary role of the hormone ghrelin in the regulation of body weight?