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GLP-1 Body Composition Check-In

Free, no-login check-in for muscle-retention risk, protein status, calorie context, and training adequacy while on a GLP-1 medication. Enter your own numbers below. Estimates only, not medical advice.

Fitness methodology by Andrew Menechian, Head of Fitness, FitCommit|Last updated: 2026-05-15

Medication Boundary

  • This tracker is nutrition and training support, not medical advice.
  • Do not change your medication dose, timing, or schedule based on this page.
  • Talk with the prescribing clinician if nausea, dizziness, dehydration, constipation, very low intake, or medication questions show up.
  • If you experience sudden vision loss or rapidly worsening eyesight while taking semaglutide, contact the prescribing clinician without delay.
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Enter your details above to see your check-in.

Why Track Body Composition on a GLP-1?

GLP-1 drugs suppress appetite so effectively that the scale can drop fast while telling you nothing about what kind of weight you are losing. Research on semaglutide (the STEP-1 trial) found roughly 40% of weight lost can be lean mass, including muscle, without protein and resistance training to counter it. Protein intake and consistent training reduce that share substantially.

This check-in compares your starting and current weight and body fat percentage to estimate how much of your loss came from lean mass versus fat, and flags your protein and training inputs against the reference points used in the GLP-1 nutrition guide.

Frequently Asked Questions

Is this tracker a substitute for medical advice?

No. This tracker gives nutrition and training estimates based on your entered numbers. It does not diagnose, treat, or give medication or dosing advice. Talk to your prescribing clinician about your GLP-1 medication, dose, or any symptoms.

How much of my weight loss should come from lean mass?

Research on GLP-1 drugs shows roughly 40% of weight lost can be lean mass without intervention. With adequate protein and resistance training, that share typically drops toward 20% or less. This tracker flags your entered numbers against that 20% reference point, it does not measure your actual body composition for you.

What is a safe rate of weight loss on a GLP-1?

A common reference point is up to about 1% of body weight per week. Faster loss increases the share that comes from lean mass rather than fat. If your entered numbers show a faster rate, slowing down (with your clinician's guidance) is one of the few levers that protects muscle.

Why does the calorie estimate say "context" instead of a target?

GLP-1 drugs suppress appetite, so eating to hunger can mean eating far below maintenance without noticing. The number here is your estimated maintenance calories (TDEE), for context on how far below it you may be running. For a full macro breakdown, use the TDEE calculator.

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