Chapter 24 — Self-Check Quiz

20 questions. Answers with explanations at the end. Aim for 16+.

Questions

1. Heritability of BMI, from twin and adoption studies, is approximately:

• a) Under 10%
• b) 40–70%, comparable to height
• c) 95%
• d) Not measurable

2. The population-level rise in body weight over fifty years is best explained by:

• a) Genetic change
• b) The food environment
• c) A decline in individual willpower
• d) Improved measurement

3. Which is described as the most actionable and least discussed determinant in §24.1b?

• a) Genetics
• b) Medications
• c) Sleep
• d) Early-life factors

4. The feedback asymmetry between loss and maintenance is that:

• a) Both are equally rewarding
• b) Loss is intrinsically reinforcing; maintenance produces no signal — the reward is that nothing happened
• c) Maintenance is more rewarding
• d) Neither produces feedback

5. Adaptive thermogenesis refers to:

• a) Any fall in metabolic rate after weight loss
• b) Metabolic rate falling MORE than the tissue loss predicts
• c) Increased heat production during dieting
• d) Brown fat activation

6. Regarding adaptive thermogenesis, the chapter concludes:

• a) It doesn't exist
• b) It occurs (✅), but its magnitude and persistence are genuinely disputed, and at typical magnitudes it is not large enough to explain the regain
• c) It fully explains weight regain
• d) It only affects women

7. The Biggest Loser follow-up (Fothergill et al., 2016) should not be generalized because:

• a) The data were fabricated
• b) n=14, the intervention was extreme and unlike clinical weight management, and other populations show smaller or resolving adaptation
• c) It was never peer reviewed
• d) It measured the wrong outcome

8. After weight loss, Sumithran et al. (2011) found:

• a) Ghrelin down and leptin up
• b) Ghrelin up; leptin, PYY and CCK down; subjective hunger up — still present at 12 months
• c) No hormonal changes
• d) Changes that resolved within four weeks

9. The body defends lost weight primarily through:

• a) Metabolic rate
• b) Appetite regulation
• c) Thyroid suppression
• d) Reduced nutrient absorption

10. Which asymmetry must any model of weight regulation explain?

• a) The body defends against gain more vigorously than loss
• b) The body defends against loss far more vigorously than against gain
• c) Defence is symmetrical
• d) There is no defence

11. The National Weight Control Registry shows that its members:

• a) Rarely exercise
• b) Exercise around an hour a day, most commonly walking, and self-monitor frequently
• c) Follow a single specific diet
• d) All used medication

12. The registry's central limitation is:

• a) It is too small
• b) Survivorship — it contains only those who succeeded, and cannot show that its listed behaviours cause maintenance
• c) It is industry funded
• d) It only enrolls Americans

13. The Diabetes Prevention Program achieved roughly 7% weight loss and reduced progression to type 2 diabetes by approximately:

• a) 5%
• b) 58%, outperforming metformin
• c) 95%
• d) It showed no effect

14. Look AHEAD found that intensive lifestyle intervention in people with type 2 diabetes:

• a) Reduced cardiovascular events substantially
• b) Did not reduce cardiovascular events, but improved remission, mobility, sleep apnoea, quality of life and medication requirements
• c) Increased mortality
• d) Produced no weight loss

15. The most likely explanation for a weight-loss plateau is:

• a) Metabolic damage
• b) Intake has risen without a decision being made
• c) Thyroid failure
• d) Starvation mode

16. Prospective research on weight discrimination finds it is associated with:

• a) Subsequent weight loss
• b) Subsequent weight gain, plus healthcare avoidance and disordered eating
• c) No measurable effects
• d) Improved motivation

17. GLP-1 receptor agonists work principally by:

• a) Blocking fat absorption
• b) Acting on appetite regulation — the same system §24.5 identified as the mechanism of regain
• c) Raising metabolic rate substantially
• d) Preventing carbohydrate digestion

18. On discontinuing a GLP-1 agonist:

• a) Weight loss is permanent
• b) Substantial regain occurs — these are treatments for a chronic condition, not a course
• c) Weight continues to fall
• d) No data exist

19. Diabetes remission after bariatric surgery often occurs before much weight is lost because:

• a) The measurement is inaccurate
• b) The procedures substantially alter gut hormone signalling, including GLP-1
• c) Patients stop eating entirely
• d) It doesn't — remission always follows weight loss

20. The chapter's position on "weight loss is futile and shouldn't be attempted" is:

• a) Correct
• b) 🟠 — it was a defensible reading of the evidence in 2015 and is no longer
• c) Untestable
• d) Correct for everyone except athletes

Answers

1. b) 40–70%. ⚠️ Comparable to height — twin and adoption studies converge on this, hundreds of common variants have been identified with small individual effects, and rare monogenic forms exist. §24.1b.

2. b) The food environment. ⚠️ The genes didn't change in fifty years. Both facts hold at once: individual differences are substantially genetic AND the population rise is environmental — they answer different questions, and most public arguments involve one side answering the question the other didn't ask. §24.1b, Chapter 22.

3. b) Medications. ⚠️ Several antipsychotics, some antidepressants, corticosteroids, insulin and sulfonylureas, some antiepileptics and hormonal treatments can cause substantial gain. If someone gained 12 kg after starting a medication, that's a prescriber conversation about alternatives and monitoring — not a diet. Check the timeline first. §24.1b.

4. b) Loss is reinforcing; maintenance produces no signal. ⚠️ The reward for a year of successful maintenance is that nothing happened. Chapter 10 §10.4's adherence finding in its harshest form: the behaviour that must persist longest has the weakest reinforcement — which is why §24.7's self-monitoring finding matters, and §24.14's step 4. §24.2.

5. b) Falling MORE than tissue loss predicts. Some fall is expected — a smaller body costs less to run. ⚠️ The question is the excess. §24.3.

6. b) It occurs, magnitude and persistence disputed, and it's not large enough to explain regain. ⚠️ A hundred kcal a day is real, matters, and does not account for a 15 kg return. Which is what points at §24.5. §24.3.

7. b) n=14, extreme intervention, other populations differ. ⚠️ The study demonstrates that severe, rapid weight loss can produce large and durable adaptation. It does not establish that this happens to everyone who loses 10 kg over six months — and it gets cited as though it did, by both sides. §24.4.

8. b) Ghrelin up; leptin, PYY, CCK down; hunger up — still present at 12 months. ⚠️ The duration is the crucial finding. §24.5.

9. b) Appetite regulation. ⚠️ This is the chapter's key correction and it gets a fraction of the attention metabolic rate does. A person who has lost 15 kg is fighting persistent, hormonally-driven hunger every day, indefinitely — and unlike metabolic rate, they feel it, can't demonstrate it, and are routinely told it's in their head. It is in their blood, and it has been measured. §24.5.

10. b) Defence against loss is far more vigorous than against gain. ⚠️ Which makes evolutionary sense and is spectacularly badly matched to a food environment engineered for overconsumption. The dual intervention point model handles this best. §24.6.

11. b) ~1 hour/day of activity and frequent self-monitoring. ⚠️ Note that the exercise volume is far more than most weight-loss guidance recommends — and the registry suggests activity matters much more for MAINTENANCE than for LOSS, which is the reverse of how it's sold. §24.7.

12. b) Survivorship. ⚠️ If a hundred people attempt loss and ten maintain, the registry contains the ten — and if the ninety were doing identical things, the registry would look the same and the behaviours would be worthless as predictors. It establishes that maintenance is possible and what it looks like from the inside. It does not establish a route. §24.7.

13. b) ~58%, outperforming metformin (~31%). ⚠️ Seven percent weight loss. Not thirty. Modest weight loss produces disproportionate health benefit, and this is the most under-taught fact in the chapter. §24.8.

14. b) No CV event reduction, but real benefits elsewhere. ⚠️ The trial was stopped for futility on the cardiovascular endpoint. Both DPP and Look AHEAD are real and both should be taught: lifestyle intervention prevents diabetes impressively and did not, in that trial, prevent heart attacks. §24.8.

15. b) Intake has risen without a decision. ⚠️ By a wide margin — Chapter 21 Case Study 1's compensation curve. The rule: if the scale hasn't moved in two weeks, measure intake before changing anything. (The other two: expenditure has fallen, and water/glycogen masking — Chapter 4 §4.8's weight-is-not-fat point.) §24.8b.

16. b) Subsequent weight gain, healthcare avoidance, disordered eating. ⚠️ Shame is not an intervention — there's no evidence it works and reasonable evidence it backfires. For clinicians the operative finding is healthcare avoidance: a patient who stops attending has not been helped by candour, whatever was intended. §24.9.

17. b) Appetite regulation. ⚠️ They mimic a gut hormone released after eating (Chapter 3 §3.6). Which is a striking vindication of §24.5: the drugs work because the problem was appetite regulation all along. Mechanism identified first, treatment followed — which is how this is supposed to go and in nutrition almost never does. §24.11.

18. b) Substantial regain — a chronic treatment, not a course. ⚠️ Unremarkable for antihypertensives and startling to people when it's weight. §24.11.

19. b) Altered gut hormone signalling, including GLP-1. ⚠️ The mechanism is not primarily mechanical restriction, which surprises people. §24.12.

20. b) Defensible in 2015, not now. ⚠️ A pharmacological intervention that acts on the actual mechanism of regain and produces outcome benefit (SELECT) is a different situation. Claim 4 is the honest-sounding conclusion from claims 2 and 3, and it doesn't follow. §24.1, §24.11.

Scoring

Three items worth checking regardless of score.

Question 9. ⚠️ If you had "metabolic rate," you have the standard model and it's the wrong one. Everything about how you'd counsel someone changes when the answer is appetite.

Question 3. ⚠️ The medication question takes thirty seconds and is skipped constantly.

Question 16. ⚠️ If you thought stigma motivates, the evidence runs the other way — and this is the item most likely to change how you speak to someone.