GLP-1 and lean mass loss: why you need movement to retain muscle

GLP-1 medications are having a strong and fast impact. Patients are losing weight and in the short term, results are positive.

These medications work effectively to promote fast weight loss by curbing appetite, slowing gastric emptying, and improving glycemic control. The possibility of delivering these outcomes without stimulants or surgery represents a significant step forward for obesity treatment.

However, employers and insurers need to make sure that GLP-1 drug usage is supported by regular physical activity over a longer time horizon to protect against longer term risk factors. One clinically significant issue in particular often goes unnoticed.

GLP-1-induced lean mass loss is a hidden danger

The cost of muscle loss can be significant for patients and health insurers alike.

Up to 39% of lean muscle mass is lost during GLP-1 medication usage.₁

Muscle loss often goes unnoticed during GLP-1 treatment programs and this won’t show up in pharmacy claims.₁

• Lean muscle loss is rarely coded as a primary condition. Sarcopenia (a condition characterized by progressive loss of skeletal muscle mass and strength)¹⁵ is underdiagnosed in clinical settings, particularly when it is medication-induced or occurs in non-elderly populations₅.
• Patients are unlikely to monitor this risk factor. However, the downstream impact of lean muscle loss is significant and serious, leading to an increased risk of musculoskeletal conditions.¹⁵
• Sedentary GLP-1 users are at higher risk. Without structured physical activity or strength training, muscle atrophy can occur gradually. This secondary effect is likely to go unnoticed as the required strength assessments or body composition testing are rarely practiced.¹⁴

Thankfully, the solution is simple, effective, and affordable. GLP-1 prescriptions can be supported by structured movement programs like Sword Move to help patients develop regular physical activity patterns and protect against muscle loss.

How GLP-1s contribute to lean mass loss 

GLP-1 medications mimic a hormone that helps regulate hunger and digestion. By reducing appetite and slowing the rate of digestion, patients tend to eat smaller portions and less frequently. This leads to a significant reduction in calorie intake, contributing to weight loss observed on the scale.₁

Importantly, not all weight lost is fat.

GLP-1 drugs are non-selective. 

Without a supporting treatment plan to prevent lean muscle loss, both fat and lean tissue are lost.

The likelihood of muscle loss skyrockets for individuals who are already sedentary, as they lack established habits of regular physical activity.²

Fewer than 1 in 4 U.S. adults meet CDC guidelines for aerobic and muscle-strengthening activity.₂

Most of your existing members aren’t moving enough to retain muscle when they begin to lower their calorie intake. A snapshot analysis of the Sword Move population shows this risk factor is widespread³:

• 77% of members are overweight or obese
• 64% have a metabolic condition (e.g., diabetes, high cholesterol)
• 55% report difficulty with basic physical activity

The takeaway learning for insurers and employers with GLP-1 spend is clear. Prescriptions should be supported by structured movement plans to ensure patients engage in regular physical activity and to prevent muscle loss.

Why lean muscle mass retention is critical for sustained weight loss

Muscle loss adds nearly $900 in excess healthcare costs per employee annually.₄ 

So what’s happening in the patient’s body that leads to these huge downstream costs?

Lean muscle mass includes metabolically active tissue that powers movement needed for daily life and underpins long-term health. 

How lean muscle protects the body

• Supports joint integrity and reduces stress on the MSK system¹⁴
• Protects against falls through balance and coordination⁶
• Drives resting metabolism, even outside of exercise¹
• Enhances insulin sensitivity and glucose control¹
• Enables functional independence, from walking to standing¹

• Enhances insulin sensitivity and glucose control¹

When muscle is lost during weight loss programs (especially if fat is regained after discontinuation) patients often end up with worse body composition¹ and increased cardiometabolic and musculoskeletal risk⁴. This reversal undermines the original goals of weight loss, both clinically and financially.

Research shows that muscle mass plays a protective role across multiple systems in the body, from maintaining metabolic health to preventing MSK pain and instability.⁴

When GLP-1 users lose lean mass, they also lose strength, balance, and resilience. All of these attributes are crucial for function and injury prevention.

Muscle loss over a broad member population often leads to:

• Higher MSK claims from pain and overuse injuries⁵
• More fall-related injuries and disability claims⁶
• Lower ability to maintain weight loss without ongoing pharmacological support¹⁶
• Reduced adherence and higher re-prescription rates for GLP-1s₉

The resulting downstream costs including physical therapy, imaging, medication, and even surgical interventions, are often preventable with proactive lean mass preservation strategies.⁴

The clinical risks of GLP-1 lean mass loss

Lean mass loss isn’t just a side effect. It’s a predictive risk factor for costly, preventable conditions.

Clinical research shows:

• Sarcopenia (including medication-induced forms) causes up to 33% of chronic pain in older adults
• Increases fall risk by 60%, driving fractures, hospital stays, and PT utilization
• In sarcopenic obesity, disability risk is 2.5x higher

These risks impact:

• Return-to-work timelines
• Independence in daily life
• Long-term physical therapy and imaging spend⁵
• Claims exposure associated with related conditions⁷

Unfortunately these incidences are rarely connected back to lean muscle mass loss during GLP-1 treatment.

GLP-1 lean mass loss doesn’t always show up in claims 

Lean tissue degradation doesn’t have a neat ICD-10 code. But the effects ripple across data sets:

• Members who lose weight but develop new MSK pain₉
• Increases in fall-related ER visits among previously low-risk members⁶
• Energy decline and functional loss despite weight loss⁴
• Reduced success with activities of daily living, particularly in regular tasks like climbing stairs, rising from chairs, or carrying groceries⁴

Perhaps the most expensive risk factor is re-prescription of GLP-1s.

This can happen as patients experience poor functional retention, with studies showing that functional decline can limit patients’ ability to maintain weight loss without ongoing medication.⁸

GLP-1s may help with short-term weight loss, but if they erode lean muscle mass, joint health and patient stability, the dangers of this long-term deterioration start to outweigh the benefits.

Movement is the proven path to preserve lean mass

The only clinically validated strategy to protect lean tissue during pharmacological weight loss is structured, strength-building movement.¹⁴

That means:

• Resistance training that builds or maintains muscle
• Progressive overload tailored to individual fitness and condition
• Wearable integration for adherence and safety
• Clinical oversight for accountability

Without this, lean GLP-1 patients risk the serious dangers of lean muscle loss.

In addition, one of the biggest concerns with GLP-1 use is sustainability. So many people rebound to old habits after stopping treatment.

• Up to two-thirds of lost weight is regained within the first year after stopping⁸
• And up to two-thirds of lost weight is regained within the first year after stopping₉

Prescribing structured movement plans to support GLP-1 medication helps to develop positive behavior change and establish a physical activity routine. These regular movement patterns allow the patient to retain lean muscle mass even when calorie intake is lowered and weight is lost.¹⁴

Sword Move: real-world data on lean mass retention in GLP-1 users

Sword Move delivers movement-first care designed to preserve lean body mass at scale. Here’s what we’ve seen:

• 69% of “inactive” and “insufficiently active” members reach “active or healthy active” status within 10 weeks⁰
• Sedentary time reduced by 1 hour 22 minutes per day for previously “inactive” or “insufficiently active” members¹¹
• Members completed an average of 4.5 guided movement sessions per week₁₂
• 91% of members reported feeling moderately or much better₊₁₃

These results lead to:

• Lower MSK claims¹²
• Better functional outcomes¹³
• Improved GLP-1 satisfaction and adherence¹³
• Fewer re-prescriptions and better long-term outcomes⁸

How Move works

Sword Move is a digital, physical therapist-supervised solution designed to counteract the muscle loss and mobility decline that can accompany GLP-1 therapy. The program combines clinically validated movement plans with wearable sensors, AI-powered feedback, and continuous clinical support.

Key elements of Move:

• Personalized strength-building movement plans
• Real-time guidance via the Move wearable (or the patient's own wearable), and the Move app
• Ongoing supervision from a specialist with a Doctor in Physical Therapy who makes program adjustments based on individual progress
• Reporting on functional improvement, adherence, and member-reported outcomes

Move mitigates the MSK risks of GLP-1 treatment and drives long-term behavior change. That means more effective health outcomes and more effective healthcare spend.  

What's next for fast and effective implementation

To maximize your GLP-1 investment and protect against downstream cost exposure, leading employers and health plans are taking action now. 

Here’s how to build a more sustainable, outcomes-focused care model:

1. Conduct a retrospective MSK audit. Identify claims 6–12 months post-GLP-1 initiation, especially related to pain, falls, or functional loss.
2. Flag high-risk members. Look for those with rapid weight loss, sedentary baseline activity, or new MSK complaints.
3. Implement a movement-first care model. Require structured activity programs as part of your GLP-1 benefit design.
4. Track functional outcomes. Partner with vendors who measure more than weight: activity level, strength, stability, and daily functioning.

Protect GLP-1 investments with Sword Move

GLP-1s suppress appetite, but they can accelerate muscle loss without movement. Sword Move fills this clinical gap with structured, measurable care.

The result? 

Stronger members, fewer MSK claims, and better ROI from GLP-1 treatment.

Don’t let muscle loss erode your outcomes. Pair GLP-1 prescriptions with Move to build strength, resilience, and long-term health.

Speak to a Sword Move expert to see how Move supports scalable, cost-effective GLP-1 strategies. 

FAQ: GLP-1 lean mass loss

Is lean mass loss a known side effect of GLP-1s?Yes. Clinical trials show up to 39% of lean muscle mass can be lost during treatment, especially in sedentary users.

Why don’t we see this in the data?It’s not usually coded. But the impact shows up through secondary indicators: MSK pain, injury claims, and mobility loss.

What can employers or health plans do?Offer movement-first care before, during, or after GLP-1 use and partner with providers who measure functional outcomes, not just weight change.