Combining Semaglutide With Exercise Preserves Muscle, Boosts Fat Loss

Resistance training may help preserve lean mass during GLP-1 therapy, according to new research.

New Research Tackles the Top GLP-1 Concern

One of the most persistent concerns surrounding GLP-1 receptor agonist medications like semaglutide has been the potential loss of lean muscle mass during treatment. New data presented at the 2026 European Atherosclerosis Society (EAS) Congress may offer a practical solution: combining the medication with structured exercise.

According to research shared at the EAS meeting and reported by EMJ Reviews, a preclinical study found that subjects receiving semaglutide alongside an exercise regimen achieved approximately 45% fat loss, compared to roughly 31% with the drug alone. Perhaps more notably, lean mass loss was reduced from about 11% in the medication-only group to approximately 8% in the combined exercise group.

What the Data Suggests About Body Composition

The findings align with a growing body of evidence suggesting that the lean mass reduction observed during GLP-1 therapy is not necessarily the same as selective muscle wasting. According to researchers, much of the reported "lean mass" lost during significant weight loss includes body water, glycogen stores, and organ mass — not exclusively skeletal muscle tissue.

A separate real-world analysis presented at the European Congress on Obesity (ECO) 2026, which examined 486 patients treated with GLP-1 or dual GIP/GLP-1 receptor agonists, found that:

• Approximately 80–85% of total weight lost was fat mass
• Relative skeletal muscle mass remained largely stable over time
• Overall body composition ratios tended to improve with treatment

These findings suggest that when patients lose weight on medications like semaglutide, the proportion of fat lost may be more favorable than previously assumed.

The LEAN-PREP Trial: A Closer Look

Building on these findings, the LEAN-PREP study (LEAN mass Preservation with Resistance Exercise and Protein during semaglutide and tirzepatide therapy) is a six-month randomized controlled trial being conducted at the Dasman Diabetes Institute. According to its ClinicalTrials.gov registration (NCT06885736), the trial has enrolled 232 participants and is examining four approaches:

• GLP-1 therapy alone (control group)
• GLP-1 therapy with home-based resistance exercise (three sessions per week)
• GLP-1 therapy with increased protein supplementation (targeting 1.6 g/kg/day)
• GLP-1 therapy with both resistance exercise and protein supplementation combined

The study protocol, published in April 2026, aims to determine whether resistance training, higher protein intake, or both can meaningfully preserve muscle mass and physical function in adults with obesity who are starting GLP-1 medications.

What Experts Recommend for Patients

While full results from the LEAN-PREP trial are still pending, current expert guidance — supported by the EAS and ECO data — suggests several strategies for those considering or currently using semaglutide treatment programs:

• Engaging in resistance or strength training at least two to three times per week
• Aiming for daily protein intake of approximately 1.2–1.6 grams per kilogram of body weight
• Starting exercise early in treatment, ideally within the first few weeks
• Tracking progress through body composition measures rather than scale weight alone

According to a BMJ analysis, the combination of structured exercise with GLP-1 therapy may also provide additional cardiometabolic benefits beyond body composition improvements, including better blood pressure and lipid profiles.

The Bigger Picture

These findings represent an important step in addressing patient and clinician concerns about muscle preservation during GLP-1 therapy. While more data from controlled human trials like LEAN-PREP is needed, the early evidence suggests that pairing medication with lifestyle interventions may optimize outcomes. Patients interested in learning whether they may be candidates for these therapies can check if they qualify.

This article is for informational purposes only and is not medical advice. Consult your healthcare provider before starting any weight loss medication or treatment.