Most protein calculators use your total weight. LeanFuel uses the U.S. Navy Method to find your real body fat %, then gives you a protein target based on your lean mass — the muscle you actually need to fuel.
Requires iOS 18.0 or later. No account needed.
Science-backed body composition analysis meets daily protein tracking.
Enter your neck, waist, and height measurements to get an accurate body fat percentage — no DEXA scan needed. Supports both imperial and metric units.
Your daily protein target is calculated from your lean body mass and fitness goal — build muscle, lose fat, recomp, or maintain. Adjusts for activity level too.
Pre-loaded with 100+ foods across 11 categories, each with USDA-verified protein values. Quick-log in one tap or add your own custom foods.
Watch your body fat % trend down and lean mass trend up over time. Protein adherence charts show how consistently you hit your daily target.
Earn XP for logging protein, hitting targets, and measuring. Level up through 15 ranks, unlock 18 badges, and maintain daily streaks to stay motivated.
Glance at your daily protein progress right from your home screen. Small and medium widgets show your protein ring, target, and body fat percentage.
Daily protein reminders that adapt to your progress — telling you exactly how many grams you have left. Monthly measurement reminders keep you on track.
Fully localized in 30 languages including Japanese, Korean, Chinese, Arabic, Hebrew, Thai, and all major European languages. Food names translated too.
A dark, focused interface designed to keep you on target.
Built on peer-reviewed research and the USDA FoodData Central database.
LeanFuel uses the U.S. Navy Method, a scientifically validated formula that estimates body fat from simple tape measurements (neck and waist circumference, plus hip for women). It's been used by the military for decades and correlates well with more expensive methods like DEXA scans.
Your muscles need protein — your body fat doesn't. A 220 lb person at 30% body fat has very different protein needs than a 220 lb person at 15%. By calculating your lean body mass first, LeanFuel gives you a target that actually matches the muscle tissue you're fueling.
LeanFuel offers a 7-day free trial with full access to all features. After the trial, you can continue with a weekly ($4.99/week) or yearly ($29.99/year) subscription for unlimited measurements, full charts, and all features.
Studies show the Navy Method typically estimates body fat within 1-3% of DEXA results for most people. It's most accurate when measurements are taken consistently at the same time of day. LeanFuel includes a measurement guide to help you get reliable readings.
LeanFuel comes with 100+ pre-loaded foods across 11 categories: poultry, red meat, fish, dairy, eggs, plant protein, legumes, nuts, grains, and supplements. All protein values are verified against the USDA FoodData Central database. You can also add unlimited custom foods.
No — all your data stays on your device. LeanFuel uses Apple's SwiftData framework for local storage with no cloud sync, keeping your body composition and nutrition data completely private.
Calculate your body fat %, get a smart protein target, and track your recomposition — all in one app.