Diet setup per Lyle McDonald's Intermittent Modified Fasting — RFL days, maintenance days, and weekly patterns. This calculator only covers the basics — get the book for the full method.
Right box = minutes per session.
Plus – of combined EPA/DHA (fish oil), 3–4 cups (225–325 g) of vegetables, and liberal salt/potassium (Lite-Salt). Leanest protein sources only; keep tag-along carbs and fats to ~20 g each per day. No calorie target — protein is the target.
| Macro | Grams / day | Calories | Notes |
|---|---|---|---|
| Protein | – | – | same as RFL day |
| Fat | – | – | – |
| Carbohydrate | – | – | whatever calories remain |
Swap rule: 10 g fat ⇄ 25 g carbs (~100 cal). Keep protein, EFAs and vegetables identical to the RFL day and add carbs/fats on top — a modular diet.
Days are placeholders — shuffle RFL/maintenance days freely around key workouts and social life, as long as the weekly pattern holds. Put maintenance days on your hardest training days.
If it saved you some spreadsheet time, you can support the project — thank you! ❤️
☕ Support this projectIntermittent Modified Fasting (IMF) is a flexible dieting framework from Lyle McDonald's 2026 book Intermittent Modified Fasting. Instead of a fixed daily calorie deficit, you alternate two kinds of days: very-low-calorie RFL days (a protein-sparing modified fast — lean protein, vegetables, and fish oil only, no calorie counting) and maintenance days where you eat at your full maintenance calories (TDEE). Weekly patterns range from a gentle 6:1 (one fasting day per week) through 5:2 and 4:3 alternate-day fasting up to near-continuous RFL.
It runs the book's setup charts for you: your diet category from body fat percentage (with a DEXA correction), the minimum protein target for RFL days, TDEE and full macros — protein, fat, and carbohydrates — for maintenance days, plus estimated daily deficit and weekly fat loss for every IMF pattern. Free, no sign-up, works in lb or kg on desktop and mobile. The calculator covers the basic setup only — the book explains food choices, adjustments over time, refeeds, and when to move between patterns.