Why the scale lies on GLP-1s

Weight ≠ composition

A 50 lb weight loss can be 35 lb fat + 15 lb lean mass (typical without resistance training) or 45 lb fat + 5 lb lean mass (with training + protein). The scale shows the same number. Body composition methods distinguish the two.

DEXA vs InBody vs tape measure vs scale

• DEXA scan — gold standard. Measures fat, lean, and bone density. ~$50-100/scan in major metros. Baseline + every 6 months on GLP-1 is the optimal cadence.
• InBody / BIA — bioelectrical impedance. Free at many gyms. Less accurate than DEXA (±3-5%) but consistent enough for tracking trend over months.
• Tape measure — waist, hip, thigh, upper arm. Free, accurate trend tracker. Waist-to-hip ratio independently predicts cardiovascular risk.
• Smart scales — Withings, RENPHO, etc. ±5-7% accuracy on body fat. Useful for trend if used at same time daily, not absolute value.
• Bathroom scale — total weight only. Useful but incomplete on GLP-1s.

Preserving lean mass on a GLP-1

1. 1. Protein 1.4 g/kg/day. A 180-lb adult needs ~115 g protein daily. On GLP-1-reduced appetite, this requires deliberate prioritization at every meal. Whey/casein/soy supplements help.
2. 2. Resistance training 2-3x/week. Compound lifts: squat, deadlift, bench, row, overhead press. 8-12 reps to near failure. Non-negotiable for muscle preservation.
3. 3. Daily steps 8,000+. Aerobic activity preserves cardiovascular function. Does not replace resistance training for muscle.
4. 4. Creatine 5g daily. Cheap, evidence-based, preserves lean mass during caloric deficit. Especially helpful postmenopausally.
5. 5. DEXA baseline + 6-month follow-up. Quantify your trajectory. If lean mass is dropping more than 10%, dial up protein and lifting.