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.

Research shows up to 39% of lean body mass can be lost during GLP-1 medication usage¹. Lean muscle mass isn’t just about movement or aesthetics. This tissue is needed for healthy metabolism, functional mobility, and injury prevention.

Muscle loss often goes unnoticed during GLP-1 treatment programs and this won’t show up in pharmacy claims. Patients are unlikely to monitor this risk factor in detail for themselves. However, the downstream impact of lean muscle loss is significant and serious, leading to an increased risk of musculoskeletal conditions.

Thankfully, the solution is simple, effective, and affordable.

GLP-1 prescriptions can be supported by structured movement programs 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 reduces calorie intake and results in weight lost on the scale.

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 those individuals who are already sedentary as they don’t have established habits of regular physical activity.

Fewer than 1 in 4 U.S. adults meet CDC guidelines for aerobic and muscle-strengthening activity².

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 population³ shows this risk factor is widespread:

• 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 annually⁴. 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 system
• Protects against falls through balance and coordination
• Drives resting metabolism, even outside of exercise
• Enables functional independence, from walking to standing

• Regulates resting metabolic rate (how many calories the body burns at rest)
• Enhances insulin sensitivity and glucose control

When muscle is lost during weight loss programs (especially if fat is regained after discontinuation) patients end up with worse body composition and higher health risk than where they started. Insurers are left to manage the escalating costs that come with downstream healthcare issues.

When GLP-1 users lose lean mass, they lose strength, balance, and resilience. These are critical risk factors putting the user at greater risk of musculoskeletal issues. Muscle loss over a broad member population often leads to:

• Higher MSK claims from pain and overuse injuries
• More fall-related injuries and disability claims
• Lower ability to maintain weight loss without pharmacological support

Downstream costs can eventuate in the form or musculoskeletal claims and surgical interventions, but this expense could be prevented with smarter preventative treatment.

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 adults⁵
• Increases fall risk by 60%, driving fractures, hospital stays, and PT utilization⁶
• In sarcopenic obesity, disability risk is 2.5x higher⁷

These risks impact:

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

Unfortunately these incidences are rarely connected back to lean 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 its effects ripple across data sets:

• Members who lose weight but develop new MSK pain
• Increases in fall-related ER visits among previously low-risk members
• Energy decline and functional loss despite weight loss
• Re-prescription of GLP-1s due to poor functional retention
• Reduced success with ADLs (activities of daily living)

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 work against the health benefits of weight loss.

Movement is the prescription needed to preserve lean mass

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

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 70% of GLP-1 users stop taking the medication within one year⁸
• 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.

Move is proven to improve outcomes for 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 previously inactive members reached “active” or “healthy active” status within 10 weeks¹⁰
• Sedentary time dropped by 1 hour and 22 minutes per day¹¹
• Members completed an average of 4.5 guided movement sessions per week¹²
• 74% reported improved well-being¹³

These results lead to:

• Lower MSK claims
• Better functional outcomes
• Improved GLP-1 satisfaction and adherence
• Fewer re-prescriptions and better long-term outcomes

FAQs: 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.