Guides

Longer explainers behind the tools: the formulas, the conventions and the mistakes worth avoiding.

• One-rep max formulas compared: Epley vs. Brzycki vs. Lombardi, and where they break down

  How the three common 1RM estimators differ, a worked example showing the gap, and how to turn an estimate into a real training percentage.

  Updated 2026-09-25

• How to estimate your maintenance calories (and why the number is only a starting point)

  Compares Mifflin-St Jeor, Harris-Benedict and Katch-McArdle BMR formulas with a worked example, then explains how to turn the estimate into a real number.

  Updated 2026-09-25

• Setting macros for a cut vs. a lean bulk

  Protein first, a fat floor, carbs as the remainder — ISSN and Helms 2014 sourcing with worked examples for both a cut and a lean bulk.

  Updated 2026-09-25

• Ideal weight formulas are from the 1970s, and weren't built for health

  Devine, Robinson, Miller and Hamwi were designed for drug dosing, not fitness goals; why waist-to-height ratio screens better than BMI.

  Updated 2026-09-25

• Hydration: what the evidence actually says about '8 glasses a day'

  Where the 8-glasses rule came from, what EFSA and IOM actually recommend, exercise and heat adjustments, and hyponatremia risk from overdrinking.

  Updated 2026-09-25

• How much protein you need per kilogram, for muscle gain and for fat loss

  What Morton's 2018 meta-analysis and the ISSN position stand say about grams of protein per kg, plus meal distribution and safety limits.

  Updated 2026-09-25

• How fast should you lose weight? What a calorie deficit actually predicts

  The 7,700 kcal-per-kg rule explained, why Kevin Hall's research shows it overstates real-world loss, and how to set a deficit with a floor.

  Updated 2026-09-25

• FFMI and the natural limit debate: what the 1995 study actually found

  Where the 'FFMI 25' natural limit claim comes from, what normalized FFMI corrects for, and where the metric genuinely breaks down.

  Updated 2026-09-25

• Body fat estimation methods compared: tape, calipers, BIA and DEXA

  Error ranges for the US Navy tape method, skinfold calipers, bioelectrical impedance and DEXA, with sources, so you know how much to trust the number.

  Updated 2026-09-25

• Activity multipliers: why most people overestimate theirs

  The activity multiplier is the biggest source of TDEE error. How to pick a conservative starting point and calibrate it with two weeks of scale data.

  Updated 2026-09-25