Lean Body Mass - Watcher is a body composition tracker for people who want to lose fat without losing muscle. Enter your weight, add body fat when you measure it, and the app tells you how much to eat today, how far your target is, and whether the week protected your muscle. Free, no account, no food logging, and your entries are stored on your phone, not on a server.

LOSE FAT, KEEP YOUR MUSCLE
• Cut only as fast as your fat can pay for it: the app caps your daily calorie deficit at what your fat mass can release, about 69 kcal per kilogram of fat a day (Alpert, 2005).
• Set your cut aggressiveness, from 0 to 100 percent of that ceiling, in three color zones: protected, aggressive, risk. The edges move with your own fat mass and stop at a calorie cap.
• Get two numbers, not one: a daily target and a minimum intake, so a bad day still has a floor.
• Stay realistic on the way down: projections stop at a lean mass ceiling, FFMI 25 for men and 22 for women.

KNOW HOW MUCH TO EAT, WITHOUT LOGGING FOOD
• No meal diary: your maintenance calories come from your smoothed lean body mass and your activity factor (Katch-McArdle), or you set them by hand.
• The calorie range follows the phase you are in and updates with every entry.
• See where you are heading: a projected date for your target body fat, recalculated every time you weigh in.

CUTTING, BULKING OR RECOMP, IN ONE APP
• The app reads your weight trend and recognizes the phase on its own, or you set it by hand.
• Cutting: a deficit bounded by what your fat stores can supply, the kind of weight loss that spares muscle.
• Bulking: set your surplus, 0 to 50 percent above maintenance. Up to 20 percent is a lean bulk and funds the muscle gain your training level allows; 21 to 30 is aggressive, 31 and up a dirty bulk. Optimal intake, maintenance plus 20 percent, sits beside your target.
• Recomp: the scale holds while lean mass climbs and fat falls, and the weekly verdict rests on that climb alone; you eat at maintenance, plus or minus 10 percent.

THE THREE NUMBERS THAT MATTER
• Weight, smoothed so a heavy water day does not read as progress.
• Body fat percentage against the target you set, with American Council on Exercise ranges, separate for men and women.
• Lean mass, derived from the two, plus FFMI and BMI with their reference zones.

READ THE WEEK AT A GLANCE
• A weekly review reads your last seven days and says in one sentence whether the week protected your muscle or cost you some, and what to change.
• Trend charts for weight and lean mass, the second with a projection band: the loss a cut should cost you, or the muscle gain a bulk or recomp should bring at your training level.
• Notes per entry for refeeds, illness or travel, marked on the chart.

TEN SECONDS A DAY
• One weight entry a day, or every other day. Body fat only on the days you measure it; the app carries your last reading forward.
• Several days at once when you catch up.
• Your history stays yours: CSV export and import when you change phones.
• Metric or imperial, light or dark, English or German.

ON YOUR PHONE, NOT ON A SERVER
• Entries are written to the app's local storage on your device. The app has no server and no account, and its code contains no analytics and no tracking.
• Nothing leaves the device unless you export it yourself, and an export is a file you then control.
• The app needs no network and keeps working in flight mode.

NOT A MEDICAL DEVICE
LBM Watcher is an informational tracking tool. It is not a medical device and does not provide medical advice, diagnosis or treatment. Its calculations follow published research, but individual physiology varies. Talk to a doctor, a registered dietitian or a sports medicine specialist before making significant changes to your diet, training or energy intake. It is intended for adults, not for children or adolescents.

For adults who take their cut, bulk or recomp seriously and want the numbers, not the noise. No ads. No tracking. No subscription.

Feym Luna

Additional Information