Chapter 17 — Exercises

Three tiers. The 🪞 and 🔄 markers indicate reflection and retrieval respectively.

Tier 1 — Recall and Comprehension

R1. Name the eight myth shapes and give the structural tell for each — without looking. Then check against §17.1. Which two did you miss? Those are the ones you're most vulnerable to.

R2. Why is the fact that urine pH changes with diet evidence against the alkaline diet claim rather than for it?

R3. A stalk of celery contains about 6 kcal. Estimate the thermic cost of digesting it and give the net figure. Show the arithmetic.

R4. What did the USDA do with its ORAC database in 2012, and what reason did it give?

R5. The blood type diet study found that some of the diets were associated with better cardiometabolic markers. Why is that a refutation rather than a confirmation?

R6. Explain, in one sentence each, why microwaving often preserves more nutrients than boiling, and why microwaves do not make food radioactive.

R7. Distinguish PTFE from PFOA from PFAS. Which is the genuine public-health concern, and is your intact frying pan the main exposure route?

R8. What is the actual mechanism by which "immune boosting" claims connect to real physiology — and at what point does the inference fail?

R9. List the four claims in §17.10 that the chapter supports, with their verdicts. What do all four have in common structurally?

R10. According to §17.12, what actually kills a myth? Give two examples and name what did the work in each.

Tier 2 — Application

A1. Run the tells. For each claim below, name every shape from §17.1 that applies, and identify which tell fires first:

a) "Lectins in beans and grains are destroying your gut lining — this is why everyone is sick." b) "Our ancestors never ate three meals a day. Your body isn't designed for it." c) "The food industry doesn't want you to know about this one root vegetable." d) "I cut out dairy, gluten, sugar and nightshades for 30 days and my joint pain vanished." e) "Cold plunges activate brown fat and switch your metabolism into fat-burning mode."

A2. The 30-second arithmetic defence. Each of these makes a quantitative claim. Convert it to calories or grams and compare it to something ordinary:

a) "Green tea burns an extra 100 calories a day" b) "Chewing gum burns 11 calories an hour" c) "Standing instead of sitting burns 50 calories an hour" d) "Grapefruit before meals melts fat"

Which of the four is arithmetically real but practically negligible? Which is simply false?

A3. Find the narrower true version. For each over-extended claim, write the version that the evidence would actually support:

a) "Sugar feeds cancer" b) "Dairy causes inflammation" c) "Gluten is bad for everyone" d) "You should eat organic to avoid pesticides" e) "Eating late at night makes you gain weight"

(You'll get the fully worked verdicts on several of these in Chapters 18–22 and 28. Write your answer first, then compare — this is a calibration exercise as much as a comprehension one.)

A4. The contamination cluster, generalized. §17.9 identified a pattern: a genuine concern converted into an inaccurate claim. Find two more examples — anywhere, not necessarily nutrition. For each, state (i) the true version, (ii) the over-extended version, and (iii) what a person who dismissed the over-extended version might wrongly conclude about the true one.

A5. Triage. Rank these by whether you would intervene, using §17.13's table. Justify the top and bottom of your ranking:

a) A colleague drinks celery juice every morning b) Your father has stopped his statin in favour of a "natural cholesterol protocol" c) A friend spends $200/month on adaptogens she can't really afford d) Your sister is putting your 6-year-old niece on a gluten-free, dairy-free diet for behaviour e) Your neighbour does a juice cleanse each January f) A pregnant friend is taking a high-dose vitamin A supplement

A6. Run the ten-minute check (§17.14) on one claim you encountered in the last week. Show your working at each stage, including which minute it died at — or didn't.

Tier 3 — Analysis and Synthesis

S1. The confidence–accuracy inversion. Theo's four highest-confidence beliefs were among his wrong ones. Propose two mechanisms that could produce this pattern, and design a way to distinguish between them. What would you need to observe?

S2. The over-extension thesis. §17.1's interlude claims the dominant failure in nutrition is over-extension rather than fabrication, and offers a 24-row table as evidence.

a) Is that table a fair sample, or is it selected by the same book making the claim? b) Identify at least one myth not in the table that is genuine fabrication rather than over-extension. c) Does the thesis hold in another field you know well?

S3. Design a myth. Construct a nutrition claim that would be maximally sticky by §17.11's criteria — resolves uncertainty, offers a visible confirmation, provides agency, confers identity, is morally legible, produces genuine reported results through bundling, and is close to unfalsifiable.

Then answer: why is this a legitimate teaching exercise rather than an irresponsible one? And: could you distinguish your invented claim from a real one using only §17.1's tells?

S4. The sceptic's failure mode. §17.9 warns that dismissing the false version of a claim can lead you to dismiss the true one.

a) Give a concrete example where this has happened at scale — in nutrition, medicine, or public health. b) Is there a rule that reliably prevents it, or is this an irreducible cost of scepticism? c) How does the six-level verdict scale used in this book help, and where does it not?

S5. Why regulation and not persuasion? §17.12 argues myths die from regulation and counted harm rather than refutation.

a) Test this against three more examples of your choosing. b) If it's true, what does that imply about the value of a book like this one? c) The chapter concedes it doesn't know how much reading a chapter changes anyone's mind. Design a study that would find out. What's your outcome measure, and what's your comparison?

S6. 🔄 The Part IV frame. This chapter dealt with claims that were not arguments. Chapters 18–22 deal with genuine debates: sugar, seed oils, organic and GMO, intermittent fasting, ultra-processed food.

Before reading them, write down for each: (i) what you currently believe, (ii) your confidence 1–5, and (iii) what evidence would change your mind. Seal it. You'll grade it at the end of Chapter 22.

⚠️ Part (iii) is the important one and the one people skip. A belief for which you cannot name disconfirming evidence is functioning exactly like the claims in this chapter, regardless of whether it's correct.

🪞 Reflection

M1. You completed the Myth Audit. Which single belief was hardest to grade honestly, and why? Was the difficulty about the evidence, or about where the belief came from?

M2. §17.13 says never to make it about intelligence — and notes that Theo, who is careful and methodical, got eight of ten wrong. Have you ever been on the receiving end of a correction that made it about intelligence? What did you do with the information?

M3. The chapter asks you to set a three-year reminder because some of what it told you will be wrong by then. Which chapter of this book do you think is most likely to need revising, and why that one?

M4. §17.11 lists agency and identity among the reasons myths stick. Is there a belief you hold — about food or otherwise — that you'd be reluctant to give up for reasons that aren't evidential? You don't have to abandon it. Just name it.