Why muscle loss happens
Two mechanisms: (1) calorie deficit — appetite drops, body breaks down both fat and muscle for energy; (2) reduced protein intake — nausea and meat aversion at higher doses can reduce protein specifically. STEP-1 sub-analysis showed ~30-40% of weight lost on semaglutide 2.4 mg was lean mass — similar to bariatric surgery and prolonged caloric restriction.
Protein target on GLP-1
ACSM recommends 1.6-2.0 g/kg of target body weight (not current weight) during weight loss for resistance-training adults.
| Target weight | Protein/day | Per meal (4 meals) |
|---|---|---|
| 140 lb | 100-130 g | 25-32 g |
| 160 lb | 115-145 g | 29-36 g |
| 180 lb | 130-165 g | 33-41 g |
| 200 lb | 145-180 g | 36-45 g |
Practical sources (GLP-1-friendly volumes)
- 4 oz chicken breast: 30g · 165 kcal
- 4 oz salmon: 25g · 230 kcal
- 1 scoop whey: 24g · 120 kcal (smoothies for solid-food aversion)
- 1 cup Greek yogurt: 17g · 130 kcal
- 4 eggs: 24g · 280 kcal
Resistance training program
Minimum effective dose: 2-3 sessions/week, major muscle groups, 6-12 reps, 2-4 sets per movement.
Full-body 3x weekly (Mon/Wed/Fri)
- Squat or leg press: 3 × 8
- Romanian deadlift: 3 × 8
- Bench press: 3 × 8
- Row: 3 × 8
- Overhead press: 2 × 10
- Farmer carry: 3 × 30s
Creatine and supplements
- Creatine monohydrate, 3-5g/day: highest-evidence supplement for muscle preservation in a deficit
- Vitamin D + B12: common deficiencies; supplement if labs show deficiency
- Hydration: 2.5-3L water daily
- BCAAs: redundant if protein intake is hit
How to monitor
- DEXA every 6-12 months (gold standard)
- InBody/BIA every 4-8 weeks (trend useful)
- Grip strength dynamometer (simple proxy)
- Reps maintained at constant load = lean mass preserved
Red flags suggesting sarcopenia
- Strength dropping 15%+ at same dose/volume
- Grip strength below age/sex norms
- Fatigue disproportionate to calories
- Inability to do normal daily activities
- DEXA showing >40% of weight lost is lean mass
If any appear, reduce GLP-1 dose, increase protein, add resistance sessions.