Track the whole picture, not just the scale.
On GLP-1 medication or a peptide, the weight that comes off is a mix of fat and lean tissue, and the scale alone cannot show which. Composa brings your medication log, food and weekly measurements together, and estimates how your body composition is trending — free, with no scan to book and no smart scale to buy.
How the estimates work
Body-composition trends are estimated from your weight and tape measurements. Composa uses the US Navy circumference method — your waist and neck (and hips, for women) with your height — to estimate body-fat percentage, then works out estimated fat mass and fat-free mass from your weight. Without a waist measurement there is no estimate: nothing is assumed about how your weight change splits.
What you record: weight, tape measurements, food, medication doses, steps and photos. What Composa estimates: body-fat percentage, fat mass and fat-free mass, your protein target and calorie floor. Composa does not use scan data today, so every composition figure is an estimate and is labelled as one.
Limits: tape-based estimates move with how and when you measure, hydration and the time of day, so trends across several weeks mean more than any single number. Fat-free mass is everything that is not estimated fat — muscle, water, bone and organs — so it is not a muscle measurement. An estimate that looks unusual (for example fat-free mass rising while your weight falls) is marked as needing a re-check rather than shown as a result. Muscle Protection shows the protein and strength training you logged — the habits that help protect muscle — not a score.
What you can do, free
Log any medication or peptide, with dose reminders. Keep a food diary — search foods, scan a barcode, describe a meal or log one you saved — and work towards a protein target. Track your weight and tape measurements and see your body-composition estimates. Keep a daily log, steps, habits and private progress photos. Read the Community. Export or delete your data at any time.
Optional paid coaching
Composa Coaching is a named human coach who reads your week and writes back: a weekly check-in with a written or voice review, messages between check-ins (asynchronous, not live chat), the Off-ramp planning screen for when your medication changes, and posting in the Community. You apply first; your coach and start date are agreed with you before you pay. Composa Plus and personal training are not on sale yet.
What Composa is not
Composa is not a medical device and gives no medical advice, no dosing guidance and no diagnosis — anything about your medication is a conversation for your prescriber, not an app. There is no AI pretending to be a human coach here: coaching is delivered by a named person.
Getting started
Composa works in your web browser on iPhone, Android and computer — add it to your home screen. There is no app-store download yet.
Start free