Appendix B — Calculation Toolkit
⚠️ CONTENT NOTE, and it changes how this appendix is written.
⚠️ This appendix contains formulas that produce numbers about your body and your intake. ⚠️ Chapter 34 §34.7 named exactly this as a way nutrition material can act as a vector, and Chapter 38 §38.1 conceded that no framing prevents it.
⚠️ So: every calculation here comes with its error bars, because the error bars are usually larger than people assume and are the most useful part.
⚠️ If you are unwell in the way Chapter 34 describes, or if numbers about your body function as targets for you, this appendix is not for you and §34.14 is.
1. ⚠️ Read this before any calculation below
⚠️ Every equation here is a POPULATION ESTIMATE applied to one person, and the error is not small.
| ⚠️ What people assume | ⚠️ What is true |
|---|---|
| ⚠️ These formulas give my number | ⚠️ They give a population average for someone with my inputs. Individual variation around it is substantial |
| ⚠️ More decimal places = more accuracy | ⚠️ A result of "2,347 kcal" is a result of "roughly 2,300, give or take a few hundred" |
| ⚠️ If my weight doesn't change as predicted, the formula was right and I was wrong | ⚠️ Ch 24: adaptive changes in appetite and expenditure are real, and self-reported intake is unreliable (Ch 3) |
⚠️ Chapter 4's threshold applies to this entire appendix: energy balance is thermodynamically true and behaviourally insufficient. ⚠️ A correct equation does not become a plan.
2. Resting metabolic rate
⚠️ The Mifflin-St Jeor equation, the most commonly used:
⚠️ Men: RMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 ⚠️ Women: RMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
⚠️ Worked example — Theo, from Chapter 4:
⚠️ Male, 84 kg, 178 cm, 41 years. ⚠️ (10 × 84) + (6.25 × 178) − (5 × 41) + 5 = 840 + 1,112.5 − 205 + 5 = 1,752.5
⚠️ His measured RMR was 1,908 — about 9% higher than the equation predicted.
⚠️ That gap IS the lesson of this appendix. The equation was not wrong; it was an estimate, and he sits above the average for his inputs.
⚠️ Error to expect: roughly ±10% for most people, and worse at the extremes of body composition. ⚠️ Equations using fat-free mass (Katch-McArdle) are better if you have a reliable body composition measurement, and most people do not.
3. Total daily energy expenditure
⚠️ TDEE = RMR × activity factor
| ⚠️ Factor | ⚠️ Description |
|---|---|
| 1.2 | ⚠️ Sedentary — desk work, little movement |
| 1.375 | Light activity 1–3 days/week |
| 1.55 | Moderate 3–5 days/week |
| 1.725 | Heavy 6–7 days/week |
| 1.9 | ⚠️ Very heavy, physical job plus training |
⚠️ Theo: 1,908 × ~1.4 = ~2,670 kcal, ⚠️ which is his canon figure from Chapter 4.
⚠️ The activity factor is the largest source of error in this calculation, and it is the one you choose yourself. ⚠️ Most people over-estimate it. ⚠️ The gap between 1.375 and 1.55 is several hundred calories a day, and nothing distinguishes them but a judgement.
⚠️ And the component people forget: ⚠️ NEAT — non-exercise activity thermogenesis — varies enormously between people and within one person over time, and it moves in response to energy intake (Ch 5). ⚠️ It is inside the activity factor and it is not stable.
4. Protein
⚠️ Requirement (g/day) = target (g/kg) × body weight (kg)
| ⚠️ Situation | ⚠️ g/kg/day | ⚠️ Chapter |
|---|---|---|
| ⚠️ Population minimum | ~0.8 | ⚠️ 8 — a floor, not an optimum |
| General adult, active | ~1.2–1.6 | 8, 23 |
| Resistance training | ~1.6–2.2 | ⚠️ 23 — above this, no further benefit shown |
| ⚠️ Adults over ~65 | ⚠️ ~1.2–1.5 | ⚠️ 25 — and Ch 37 §37.9 flags this as a place the book may be overconfident |
| Energy restriction | Higher end | 8, 24 |
⚠️ Distribution matters as well as total (Ch 23): ⚠️ roughly 25–40 g at each of several meals outperforms the same total concentrated in one.
5. Fibre, and the gap most people have
⚠️ Target: ~25–30 g/day. ⚠️ Typical intake in many high-income countries: substantially less.
⚠️ Theo: 14 g → ~31 g over three years (Ch 38 CS1), ⚠️ which is the single largest dietary change in this book's cast and came from adding pulses several times a week.
⚠️ Rough contributions:
⚠️ A cup of cooked lentils ~15 g · a cup of beans ~12 g · a pear or apple with skin ~4–5 g · two slices wholemeal bread ~4 g · a cup of oats ~4 g · a cup of most vegetables ~2–4 g.
⚠️ The arithmetic is why Chapter 11 and Chapter 32 both land on pulses: one portion closes about half a typical gap, and they are the cheapest food per nutrient in the shop.
6. Energy density and the label
⚠️ Energy density = kcal per 100 g. It is printed on every European label and is the most useful number on it (Ch 30).
| ⚠️ kcal/100 g | ⚠️ Category |
|---|---|
| <100 | ⚠️ Low — most vegetables, fruit, broth soups |
| 100–250 | Moderate — cooked grains, pulses, lean protein |
| 250–400 | High — breads, cheeses, drier baked goods |
| >400 | ⚠️ Very high — oils, nuts, most snack foods, chocolate |
⚠️ Chapter 22's finding runs partly through this: ultra-processed diets are typically more energy dense, and energy density predicts intake.
⚠️ Nuts are >400 and are recommended (Ch 19, Ch 37). ⚠️ Energy density is a useful variable, not a verdict — which is the error §35.5's CGM apps make in the other direction.
7. ⚠️ Cost per nutrient — the Chapter 32 calculations
⚠️ The most practically useful arithmetic in this appendix, and the one nobody does.
⚠️ Cost per 100 kcal = (price ÷ total kcal in pack) × 100 ⚠️ Cost per 10 g protein = (price ÷ total g protein in pack) × 10 ⚠️ Cost per serving of vegetables = price ÷ number of servings
⚠️ The point (Ch 32 §32.2): ⚠️ these three rank foods in DIFFERENT orders, and the dozen foods that are cheap in all three are where the answer lives.
⚠️ Waste-adjusted cost, which is the one that changes most people's number:
⚠️ Effective cost = spend ÷ (1 − waste fraction)
⚠️ Buy $180, throw away 25%, and your effective cost per meal is 33% higher than the receipt says (Ch 32 §32.4).
⚠️ And the time-value calculation (Ch 32 §32.6): ⚠️ money saved ÷ hours spent = your effective hourly rate. ⚠️ Cutting waste runs at roughly $108/hr; soaking dried beans at about $6/hr.
8. ⚠️ Hydration and sweat rate
From Chapter 15. ⚠️ The one calculation here that is genuinely individual and worth doing.
⚠️ Sweat rate (L/hr) = (pre-exercise weight − post-exercise weight + fluid consumed) ÷ hours
⚠️ Weigh before and after a session, in minimal clothing, having recorded what you drank.
⚠️ Priya Achterberg's, from Chapter 15: roughly 1.2 L/hr in warm conditions — and she had been drinking to a schedule that bore no relation to it.
⚠️ This is individual, measurable, short-latency and actionable — which is exactly Chapter 35 §35.9's description of what an n-of-1 experiment CAN answer.
9. ⚠️ What is deliberately not in this appendix
⚠️ No calorie targets for weight change. ⚠️ The "3,500 kcal per pound" rule is a linear approximation of a non-linear system and systematically over-predicts (Ch 24).
⚠️ No goal weights, no goal body compositions, no BMI interpretation tables. ⚠️ Chapter 23 §23.13 refused body-composition targets and Chapter 24 explains why weight is a defended system rather than a dial.
⚠️ No energy availability threshold. ⚠️ Chapter 34 §34.6 removed that figure deliberately: a threshold becomes "am I under it?", which is the wrong question and the one people ask.
⚠️ No macronutrient ratio prescriptions. ⚠️ Chapter 10 and Chapter 35 §35.3b between them establish that the ratio matters less than adherence and that no test predicts which suits you.
⚠️ Chapter 37 §37.3's plate has no numbers in it either, and that was the same decision made once for the whole book.
10. The honest summary
⚠️ Every calculation in this appendix is a starting estimate with error bars wider than its decimal places suggest.
⚠️ The two most useful are not about your body at all: cost per nutrient (§7) and sweat rate (§8).
⚠️ A number you calculated is not more true than a number you were given. It is just yours.
⚠️ Chapter 4's threshold, one last time: the arithmetic is correct and it is not sufficient.