Catalyst Performance
Loading
Catalyst Performance
Loading
GLP-1 / Weight-loss medications
On a GLP-1 like Ozempic, Wegovy or Mounjaro, not all of the weight you lose is fat. A large share can be muscle. Enter your numbers to estimate how much muscle is at risk, then see how to keep it.
GLP-1 medications work by cutting appetite, which puts you in a large calorie deficit. The scale moves fast, but a deficit does not choose fat for you. Across trials of these drugs, roughly 25 to 39% of the total weight lost came from lean, fat-free mass rather than fat (Prado et al. 2024). That muscle is the tissue that keeps you strong, holds your metabolic rate up, and protects the weight loss from coming back. Losing it quietly is the cost most people are not told about.
You cannot make muscle loss zero, but you can change the ratio sharply. In a randomised trial of dieting adults, those who added resistance training kept more lean mass than those who only did aerobic work (Villareal et al. 2017). Two things do the work: strength training tells your body to keep the muscle, and enough protein gives it the raw material. That is the entire job while the medication handles the fat. The GLP-1 Muscle Protocol is the 12-week strength-and-protein plan our coaches use for exactly this, written and medically reviewed by a doctor, with a complimentary sample chapter you can read first.
| Total weight lost | Likely muscle (25 to 39%) |
|---|---|
| 10 kg | about 2.5 to 3.9 kg |
| 15 kg | about 3.8 to 5.9 kg |
| 20 kg | about 5.0 to 7.8 kg |
Source: Prado et al. 2024, Lancet Diabetes Endocrinol. A range, not a precise figure: tirzepatide tends toward the lower end, and training plus protein moves you lower still.