Nutrition

GLP-1 and exercise: users are moving less, studies confirm

Research from ENDO 2026 confirms the GLP-1 paradox: users of semaglutide and tirzepatide move less after losing weight. Here's why that's dangerous and what the evidence says to do about it.

keedia July 9, 2026 · 5 min read
An injectable pen, worn running shoes, and a dumbbell abandoned on a cream surface in warm golden light.

GLP-1 and exercise: users are moving less, studies confirm

Here's the paradox nobody predicted. People take GLP-1 medications, semaglutide, tirzepatide, liraglutide, they lose significant weight, and they become less physically active than before. Research presented at ENDO 2026, the Endocrine Society's annual meeting, confirmed it with objective data across thousands of patients.

Key Takeaways

  • ENDO 2026 data shows GLP-1 users significantly decreased physical activity despite weight loss
  • GLP-1 drugs reduce fat AND lean muscle mass — resistance training is non-negotiable
  • 25-40% of total weight loss under GLP-1 can come from muscle if resistance training is absent
  • Since May 2026, Medicare GLP-1 patients must enroll in a certified lifestyle support program
  • Resistance training + adequate protein is the only validated strategy to protect muscle on GLP-1

Why GLP-1 users move less

The mechanism is counterintuitive but makes sense. GLP-1 agonists work through multiple pathways: reducing appetite, slowing gastric emptying, and modulating the brain's reward signals. That last part is the key here. GLP-1 reduces the drive to do things perceived as energetically costly, including exercise.

The ENDO 2026 study tracked patients on semaglutide, liraglutide, dulaglutide, and tirzepatide. Weight loss was real and significant. But objectively measured physical activity decreased in the majority of participants. The correlation is consistent: reduced hunger, reduced perceived available energy, reduced desire to move.

It's not that patients are making less effort. Their drive to exercise has also dropped, as a pharmacological side effect of the medication.

The real problem: you're losing muscle, not just fat

This is where the paradox gets dangerous. GLP-1 medications don't distinguish between fat mass and lean mass. Based on aggregated clinical data across major approved GLP-1 drugs, 25-40% of total weight loss can come from muscle if resistance exercise is absent.

That proportion matters. For someone losing 20kg on GLP-1 without strength training, that could mean 5-8kg of muscle lost. Short-term, that's reduced functional strength. Long-term, it's a lower resting metabolic rate — making weight maintenance after stopping treatment harder to sustain.

The medical community is unanimous: GLP-1 without resistance exercise is an incomplete strategy.

What patients and practitioners need to do

The recommendations converge on three points:

1. Resistance training is priority, not optional. At minimum, two strength sessions per week targeting all major muscle groups. The goal isn't performance. It's muscle preservation. Moderate to heavy loads with sufficient volume (10+ sets per muscle group per week per the 2026 ACSM guidelines) is the validated approach.

2. Protein intake needs to go up. Protein requirements are higher than normal under GLP-1, precisely because the body is in caloric deficit. The evidence converges on 1.6-2.2g per kg of body weight daily to preserve lean mass during a deficit.

3. Reduced appetite masks protein deficit. GLP-1 drugs cut appetite — so patients eat less, including far less protein. Active nutritional monitoring is needed to ensure protein targets are met despite overall calorie reduction. This is where a coach or dietitian adds irreplaceable value.

What the fitness industry is doing about it

The sector is moving fast. According to the Inspire360 GLP-1 Health Club Intelligence Report (March 2026), 17 fitness clubs and 10 solution providers had already created GLP-1-specific programs. These programs center resistance training and nutrition, positioning them as clinical complements to medical treatment, not alternatives.

In May 2026, the Centers for Medicare and Medicaid Services went further: Medicare GLP-1 patients are now required to enroll in a certified lifestyle support program. That creates a significant regulatory opening for gyms and coaches who build structured GLP-1 programs that meet CMS criteria.

For fitness professionals, the message is clear: GLP-1 clients aren't standard clients. They have specific physiological needs, and the clubs and coaches who address those needs correctly have a real competitive advantage — one backed by policy, not just positioning.