Semaglutide and tirzepatide are doing exactly what they’re supposed to. Suppressing appetite. Driving weight loss. Improving metabolic markers. The problem is what they’re taking with them.
You’re Losing Muscle
The STEP-1 trial (JAMA, 2021) found that 39 to 45% of weight lost on semaglutide was lean muscle mass. Not fat. Muscle. The SURMOUNT-1 trial for tirzepatide showed similar numbers. Roughly 25% lean tissue loss.
The SLIM LIVER study (2025) went further. MRI imaging showed 9.3% core muscle volume loss in GLP-1 users. Even in patients who were exercising on their own.
“GLP-1 receptor agonists and exercise: the future of lifestyle prioritization.”
Frontiers in Endocrinology, 2025
That paper argues physical therapists should be leading this effort. We agree. And we’re doing it.
It Has to Be the Right Exercise
Walking more and eating less won’t preserve muscle on a GLP-1. The case series data (PMC, 2025) shows that patients who combined GLP-1s with structured resistance training 3 to 5 times per week preserved 2 to 3 times more muscle. Some actually gained lean mass while losing 13 to 33% of their body weight.
The difference wasn’t motivation. It was programming. Progressive overload. Tracked intensities. Structured periodization. The kind of work that requires clinical oversight, not a YouTube playlist.
What We Built
Forward Physical Therapy’s GLP-1 Active Program uses our Return+ testing platform to track what matters:
- Body composition. BMI, waist-to-hip ratio, waist-to-height ratio with clinical risk classification.
- Grip strength. The single strongest predictor of all-cause mortality (PURE study, Lancet, N=139,691).
- Aerobic capacity. VO2 max estimation via Talk Test. Validated ventilatory threshold marker.
- Physical Activity Vital Sign. Weekly exercise minutes vs. CDC guidelines.
- Functional testing. Sit-to-stand power, gait speed, balance.
Every metric tracked longitudinally across your entire program. Not a snapshot. A trajectory. You see your progress. Your prescriber sees your progress. The data drives every decision.
Why Physical Therapy, Not a Gym
A gym membership doesn’t come with a diagnosis, a treatment plan, or clinical accountability. Physical therapy does. We design exercise prescriptions the same way a physician designs a medication regimen. Dosing. Progression. Monitoring. Adjustment.
GLP-1 patients often present with joint pain, deconditioning, diabetes, hypertension. That requires clinical judgment, not just a workout.
No Referral Needed
Wisconsin’s direct access law means you can start without a physician referral. Most patients are scheduled within 24 to 48 hours.
Start Your GLP-1 Exercise Program
Clinics in Edgerton and Fitchburg, WI. 1-on-1 with a Doctor of Physical Therapy.
References: Wilding et al., STEP-1, JAMA 2021. Jastreboff et al., SURMOUNT-1, NEJM 2022. SLIM LIVER, PMC 2025. Frontiers in Endocrinology, 2025. Leong et al., PURE Study, Lancet 2015.