The FFMI Check Blog

Long-form, peer-reviewed-grounded reads to help you turn raw numbers into smarter training decisions.

• Beyond BMI: Why FFMI is the Only Metric That Matters for Lifters — Body Composition · 7 min read — Why the body-mass index fails athletes — and how lean-mass-driven metrics replace it for serious training decisions.
• Can You Reach FFMI 25 Naturally? What 157 Real Lifters Showed — Sports Science · 9 min read — FFMI 25 is where naturals stop and steroid users begin — Kouri 1995 proved it with 157 lifters. Here is the exact data, the height-normalized formula, and where you actually cap out.
• The Athlete's Guide to Estimating Body Fat Percentage Safely at Home — Practical Guide · 10 min read — Garbage in, garbage out. Your FFMI is only as accurate as your body fat input — here is how to get it right without leaving your bathroom.
• Mifflin-St Jeor TDEE Calculator: Accuracy and Error Range — Energy Balance · 8 min read — The Mifflin-St Jeor equation is the most-cited TDEE formula in nutrition research. How close does it actually land to metabolic-cart measurements, and when does it fail? The data.
• TDEE Calculator to Lose Weight: The 4-Step Setup That Actually Works — Fat Loss · 9 min read — A TDEE number alone will not melt fat. Here is the four-step protocol that turns a calculator output into a calibrated, sustainable cut.
• Epley vs Brzycki 1RM Formula: Which One to Use and When — Strength · 7 min read — Epley vs Brzycki: two 1RM formulas that give different answers. See when each one is more accurate, when both fail, and the best way to combine them for a reliable estimate.
• What Is a Good FFMI? Benchmarks by Age, Height & Training Years — Body Composition · 8 min read — FFMI 20 is solid intermediate. FFMI 22 puts you in the top 10%. FFMI 25 is the natural ceiling. See exactly where you land by training years, age, and sex.
• Average FFMI by Age and Height: Complete Benchmark Table — Body Composition · 9 min read — Untrained men average FFMI 18-19. Trained lifters hit 21-23. Advanced naturals reach 24. Find the exact benchmark for your age, height, and training years.
• Golden Era Bodybuilders FFMI: Pre-Steroid Reference Chart — History & Reference · 12 min read — Reeves, Grimek, Park, Pearl — every golden-era bodybuilder FFMI reconstructed from historical records. The ground-truth reference showing what natural muscularity actually looks like.
• Macro Calculator for Muscle Gain (2026): Protein, Calories & Bulk Split — Nutrition · 11 min read — Free macro calculator for muscle gain — protein 1.6–2.2 g/kg (Morton 2018), 200–500 kcal surplus, evidence-based split. Includes the 2-week calibration loop that separates lean bulks from fat gain.
• Macro Calculator for Fat Loss (2026): Cut Fat, Keep Muscle — Nutrition · 11 min read — Free macro calculator for fat loss — protein 2.0–2.4 g/kg to protect muscle, 15–25% deficit, hormonal-minimum fat. Includes cutting split, 2-week calibration loop, and stopping criteria.
• FFMI Chart by Number: What Every Score From 17 to 28 Actually Means — FFMI · 13 min read — Every FFMI score from 17 to 28 tells a specific story about training age, lean mass, and how close you are to the natural ceiling. This is the complete reference chart with what each number means and how to reach the next one.
• TDEE Complete Guide: How to Calculate, Verify, and Use Your Number — Energy Balance · 12 min read — TDEE is the calorie number that drives every cut, bulk, and recomposition decision. Here is the complete guide: how to calculate it, verify it against reality, and use it correctly across the four common lifting goals.
• 1RM Formulas Complete Guide: Every Method Compared for Accuracy — Strength · 11 min read — Every 1RM formula — Epley, Brzycki, Lombardi, O Conner, Wathan — compared side by side. See which method is most accurate at what rep range, when they diverge, and how to pick the right one for your programming.
• Body Fat Measurement Methods Compared: Accuracy, Cost, and Best Use — Body Composition · 11 min read — DEXA ±1% costs $150. US Navy ±3% is free. Smart scales are off by 8%. Every body fat method ranked by accuracy, cost, and when to actually use it.
• FFMI for Women: What the Numbers Really Look Like — FFMI · 10 min read — Women rarely see themselves in the FFMI chart because the number was validated on male athletes. Here are the actual female ranges, the natural ceiling data, and why the "22 ceiling" for women is more contested than the male 25.
• Brzycki Formula 1RM Calculator: How the Formula Works and When to Use It — Strength · 9 min read — The Brzycki formula estimates 1RM from a submaximal set using a simple ratio. Here is how the formula works, where it beats Epley, its accuracy limits, and how to use it without over-programming your training.
• Leangains Macro Calculator: Berkhan Method (Free Guide 2026) — Nutrition · 11 min read — Martin Berkhan's Leangains method: +20% training-day surplus, −10% rest-day deficit. The exact math, the 2:1 ratio logic, and how to run it for your bodyweight.
• The AthleanX FFMI Debate: What Jeff Cavaliere Actually Says — FFMI · 9 min read — The AthleanX FFMI numbers get quoted in every "natty or not" debate on the internet. Here is what Jeff Cavaliere’s measurements actually show, why they matter for the FFMI 25 conversation, and how to read them without picking a side.
• FFMI vs Lean Body Mass: Two Metrics, One Physique — FFMI · 9 min read — Lean body mass is the raw kilograms of tissue that is not fat. FFMI is that number normalized against your height. Here is why the two numbers tell different stories and which one to use for what.
• How to Improve Your FFMI: The Realistic Playbook — FFMI · 10 min read — Improving FFMI is not a special protocol — it is the same three levers every muscle-gain plan uses (progressive overload, protein, calorie surplus), applied with the patience the FFMI scale demands. Here is the realistic playbook.
• The Most Accurate Body Fat Measurement Method: A Ranked Comparison — Body Composition · 11 min read — Which body fat method is actually the most accurate? A ranked comparison of DEXA, BOD POD, hydrostatic weighing, US Navy, InBody, calipers, and smart scales — with the accuracy data, cost, and access reality for each.
• FFMI for Men: Benchmarks, Averages, and Natural Limits by Age — FFMI · 11 min read — Every FFMI benchmark for men — averages by age, thresholds for "good", advanced, and elite natural, and where the drug-free ceiling sits. Data from NHANES, the Kouri 1995 study, and modern hypertrophy research.
• Best Macro Calculator 2026: Protein, Carbs & Fats for Every Goal — Nutrition · 14 min read — Free macro calculator with evidence-based splits for muscle gain, fat loss, and recomposition. Backed by Morton 2018, Helms 2014, and Aragon–Schoenfeld — not diet-culture heuristics.
• Built With Science vs AthleanX: FFMI, Macros, and Method Compared — Method Comparison · 11 min read — Built With Science (Jeremy Ethier) and AthleanX (Jeff Cavaliere) both build fitness content on the same peer-reviewed research base. See exactly where their FFMI thresholds, macro splits, and programming approaches align — and where the practical differences matter.
• Eric Helms FFMI: What the Natural Bodybuilding Researcher Actually Uses — Sports Science · 10 min read — Eric Helms uses Kouri 1995 FFMI, protein 1.8-2.7 g/kg LBM, and DEXA-tracked cuts. His exact formulas, his competing FFMI (~24-25), and what he actually recommends.
• Body Recomposition Macro Calculator: Lose Fat and Gain Muscle at the Same Time — Nutrition · 12 min read — Body recomposition — losing fat and gaining muscle at the same time — is real but slower than dedicated cutting or bulking. See the exact macro split, calorie target, timeline expectations, and who recomp actually works for.
• What Is FFMI? The Complete Explanation (Formula, Meaning, and Use) — FFMI · 10 min read — FFMI (Fat-Free Mass Index) is the metric BMI wishes it was — a measurement of lean muscle mass relative to your height. See what FFMI actually measures, how to calculate it, what your number means, and where the natural ceiling sits.
• FFMI 25: The Natural Ceiling Explained (Kouri, Helms, and the Real Data) — Sports Science · 10 min read — FFMI 25 is the most famous number in natural bodybuilding — the statistical ceiling separating drug-free lifters from anabolic-assisted physiques. See exactly where the number came from (Kouri 1995), who has reached it, and whether it should be your goal.
• DEXA Scan Cost 2026 + Best At-Home Alternatives Compared — Body Composition · 11 min read — DEXA scans cost $75–$200 per session — but a $30 smart scale + tape measurements deliver 80% of the insight for 1% of the cost. Here is the honest cost breakdown, accuracy comparison, and the exact home protocol that gets you to DEXA-adjacent numbers.
• Fitness Influencer Calculator Methods Compared (2026 Guide) — Named Methods · 12 min read — Jeff Nippard, AthleanX, Built With Science, Eric Helms, Martin Berkhan — each markets a distinct "method," but the underlying math is often the same. Here is what actually differs, backed by research, and which framework fits which lifter.
• Jeff Nippard vs AthleanX vs Built With Science: FFMI & Macro Method Compared — Named Methods · 10 min read — Jeff Nippard, Jeff Cavaliere (AthleanX), and Jeremy Ethier (Built With Science) all claim natural status — but their FFMI numbers, macro recommendations, and coaching styles differ meaningfully. Here is the head-to-head breakdown.
• How to Measure Body Fat Percentage: 7 Methods Compared (2026) — Body Composition · 11 min read — Seven ways to measure body fat percentage — from $200 DEXA scans to $5 tape measures. Accuracy, cost, home vs clinic, and the exact protocol that gets you within 1% of DEXA accuracy at home.
• Skinny Fat Recovery: Complete Guide for Lifters (2026) — Body Composition · 13 min read — Skinny fat is the "look thin but soft" body composition: low weight, high body fat, low FFMI. Here is the exact 12-month recomposition protocol — maintenance calories, 1.8–2.2 g/kg protein, progressive lifting — that fixes it without extreme cuts or bulks.
• Body Recomposition for Beginners: Step-by-Step Guide (2026) — Body Composition · 11 min read — Body recomposition is simultaneously losing fat and gaining muscle at the same bodyweight. This is the step-by-step protocol — exact maintenance calories, 1.8–2.2 g/kg protein, progressive lifting — that actually works for beginners.