Strength Training and Muscle Preservation
Here is a fact that surprises many people starting a peptide protocol. Weight loss with peptides can reduce lean muscle mass if you do nothing to protect it. The medication lowers your calorie intake by reducing appetite. When your body has fewer calories coming in, it looks for energy to burn. If you are not strength training, it will pull from muscle as well as fat.
Weiss et al. (2022) presented data from Novo Nordisk showing the difference exercise makes. Patients on semaglutide who strength-trained two to three times per week lost weight that was 85 percent fat and 15 percent muscle. Users on the same medication who did not exercise lost weight that was only 70 percent fat and 30 percent muscle. That is a dramatic gap in outcomes from the same medication.
The mechanism is straightforward. Resistance training signals your body to hold onto muscle even in a caloric deficit. You are giving your muscles a reason to stay.
The most studied approach uses compound movements. Squats, bench presses, deadlifts, and pull-ups work multiple muscle groups at once and stimulate the kind of systemic response that protects lean mass. Three sets of eight to twelve reps, two to three sessions per week, is enough to see results. You do not need to live in the gym.
If you want to track your progress, PeptPro pulls your strength training data from Apple Health and lets you log weight and photos to compare over time. The visual record matters because the scale does not tell the whole story when you are gaining muscle and losing fat at the same time.