Weight loss on any plan includes some lean mass, and GLP-1 medications are no different. The good news is that two simple habits help you keep more muscle.

What the trials show

  • In the STEP 1 trial of semaglutide, people lost about 15% of their body weight over 68 weeks. Body scans in a subgroup suggested close to 40% of the weight lost was lean mass.
  • In the SURMOUNT-1 trial of tirzepatide, scans suggested about a quarter of the weight lost was lean mass.

"Lean mass" on these scans includes water, glycogen and organ tissue, not only muscle, so these numbers overstate muscle loss. Still, protecting muscle is worth the effort, especially as we age.

Habit 1: enough protein, spread out

For adults losing weight, many dietitians suggest around 1.2 to 1.6 g of protein per kilogram of body weight per day. Mealpen uses about 1.4 g/kg.

  • 70 kg (154 lb): about 100 g a day
  • 90 kg (198 lb): about 125 g a day

With a small appetite, split it into 25 to 35 g at meals and 10 to 20 g at snacks, and eat the protein first. If you have kidney disease, ask your clinician for your own target.

Habit 2: strength training

Muscle is kept when it is used. Two or three short sessions a week of resistance exercise help: bodyweight squats, wall push-ups, resistance bands or weights. Walking is great for health but does not replace strength work. Check with your clinician before starting a new routine if you have health concerns.

Other things that help

  • Do not cut calories much further than the medication already does.
  • Sleep 7 to 9 hours when you can.
  • Keep moving every day.

Sources

This article shares general food ideas, not medical advice. Talk to your prescriber about your dose, side effects and any condition that changes what you should eat.