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Exercise on GLP-1 Medications

Resistance training isn't optional—it's essential. How to preserve muscle mass and optimize your workouts while losing weight.

December 2025 5 min read
The Single Most Important Thing
Resistance training 2-3x per week. This is not optional if you want to preserve muscle during rapid weight loss.

GLP-1 medications cause significant weight loss, but 25-40% of that can be lean mass (muscle, bone, connective tissue). The medication doesn't distinguish between fat and muscle—your body does. And the signal that tells your body to preserve muscle is: you're using it.

Exercise Types: What Matters Most

Essential
Resistance Training
Weights, machines, resistance bands, bodyweight exercises. 2-3 sessions per week, all major muscle groups. This signals your body to preserve muscle.
Helpful
Cardiovascular Exercise
Walking, cycling, swimming. Good for heart health and additional calorie burn. But doesn't preserve muscle like resistance training.
Helpful
Daily Movement
Steps, taking stairs, active hobbies. Contributes to overall energy expenditure and health. Easy to maintain.
Helpful
Flexibility/Balance
Yoga, stretching, mobility work. Important for injury prevention and quality of life. Especially valuable for older adults.

Practical Considerations

Energy levels may fluctuate. Especially early on, you're eating significantly less. Your body is adjusting. Don't expect PR workouts every session.

Protein timing matters. Eat protein within a few hours of resistance training. This maximizes muscle protein synthesis.

Start where you are. If you haven't exercised in years, beginning with resistance training can be daunting. Start light. Bodyweight exercises count. Build from there.

Hydration is crucial. Reduced eating often means reduced fluid intake. Dehydration impairs performance and recovery. Drink water before, during, and after exercise.

Minimum Effective Dose
  • 2-3 resistance training sessions per week
  • Hit all major muscle groups (legs, back, chest, shoulders, arms)
  • 2-3 sets of 8-12 reps per exercise
  • Progressive overload: gradually increase weight or reps over time

What About Cardio?

Cardio is great for cardiovascular health but doesn't preserve muscle. If you have limited time and energy, prioritize resistance training. Add cardio as you can—even walking counts.

That said, some combination of both is ideal. The healthiest outcome combines fat loss with maintained muscle and cardiovascular fitness.

The Bottom Line
Resistance training is essential—not optional—when using GLP-1 medications. It's the primary signal that tells your body to preserve muscle during rapid weight loss. Aim for 2-3 sessions per week hitting all major muscle groups. Combine with adequate protein intake. Cardio is beneficial for heart health but doesn't replace resistance training. Start where you are and build progressively.
Sources
  1. Research on muscle preservation during weight loss.
  2. Exercise recommendations for obesity treatment.
  3. ACSM guidelines for resistance training.