Moving Less On Your GLP-1? Here’s Why That Matters More Than The Scale
There's an assumption baked into many GLP-1 success stories. You lose weight, gain energy, and move more. It makes intuitive sense. If the pounds are coming off, you'd expect people to feel lighter, more motivated, and more active. But new research from the NIH suggests the reality is much more complicated. And a disconnect between weight loss and physical activity on these drugs may be far more common than anyone expected.
Here's what the data actually shows about movement as it relates to these drugs, and why it matters for anyone on (or considering) a GLP-1.
What the study found
A real-world study presented at the Endocrine Society’s annual meeting in Chicago tracked physical activity in over 700 adults with obesity who started GLP-1 therapy. Using Fitbit data linked to electronic health records, researchers measured daily step counts and moderate-to-vigorous physical activity before and after participants began treatment.
Analysis revealed that daily steps dropped from an average of 5,047 to 4,487, a decline of 560 steps per day. Moderate-to-vigorous physical activity fell from 27.9 to 22.2 minutes per day. Men and people with musculoskeletal pain saw the steepest declines.
In other words, GLP-1 users were losing weight, but they were also decreasing movement.
Why GLP-1 users may be moving less
The activity decline observed in the study isn't entirely surprising when you consider what these medications do to the body. GLP-1 drugs work by suppressing appetite and slowing gastric emptying, which leads to significantly reduced calorie intake. That caloric deficit can cause fatigue, nausea, and low energy, all of which make it harder to stay active.
The study also found that people with musculoskeletal pain experienced the sharpest drops in movement. Joint pain and physical discomfort are already barriers to exercise, and the side effects of GLP-1 therapy can compound them. When your body feels depleted, a walk or a workout is often the first thing to go.
There's also a subtler dynamic at play. GLP-1 medications are so effective at producing weight loss that some users may feel less urgency to exercise, as if the drug is "doing the work." But that thinking misses a critical piece of the picture.
Weight loss ≠ health
Weight loss is often treated as the finish line. Lose a couple of pounds, and better health will follow. But this is an extremely narrow-minded perspective.
When you lose weight without maintaining physical activity, a significant portion of what you lose isn't fat, it's muscle. A 2024 narrative review found that GLP-1 drugs can cause rapid and significant loss of lean mass1 of roughly 10% during treatment, an amount the authors described as comparable to a decade or more of age-related muscle loss. They said it amounted to roughly 6 kilograms, or 13 pounds, of muscle loss.
The American Heart Association made this clear in a recent statement, saying exercise delivers health benefits beyond weight loss, improving blood pressure, insulin sensitivity, cholesterol levels, and cardiorespiratory fitness in adults with overweight or obesity, independent of weight loss. Your body gets healthier whether or not the number on the scale moves.
These drugs are producing weight loss, but if activity is declining at the same time, people may be missing out on the benefits that exercise delivers on its own. The real value of movement is what it does for your heart, your metabolism, and your muscle.
And the muscle piece is especially relevant here. The AHA statement recognizes people often lose muscle along with fat when they are losing weight through calorie restriction alone, which is similar to what happens when GLP-1 drugs suppress appetite. Exercise, specifically strength training, is critical for preserving muscle mass.
To sum it up, movement is not a health bonus. It's a non-negotiable.
What intentional movement looks like on a GLP-1
Preserving muscle mass is key for longevity, especially if you are on a GLP-1. But we understand that working regular activity into your routine might feel like a big ask. Here are some tips on how to get started:
- Prioritize resistance training: Lifting weights, or doing any form of resistance exercise, is the most effective way to preserve lean mass during weight loss. Just two to three sessions a week can make a significant difference in maintaining muscle. If you're new to strength training, bodyweight exercises, resistance bands, or guided programs are all great places to start.
- Keep daily movement intentional: The study found that overall step counts declined after starting GLP-1 therapy. Rebuilding that baseline doesn't require a gym membership. A daily walk, opting to take the stairs, or breaking up long periods of sitting with exercise snacks all count. Treat movement as a non-negotiable part of your day, not something that happens when you have energy left over.
- Don't let side effects become a permanent excuse: Nausea, fatigue, and low appetite are real and common in the early weeks of GLP-1 therapy, so it's completely reasonable to scale back intensity during that adjustment period. But as your body adapts to the medicine, gradually reintroducing structured movement. Even 10 to 15 minutes of exercise can affect your long-term health outcomes.
- Pair movement with protein: Adequate protein intake works in tandem with exercise to preserve lean mass during weight loss. Prioritizing protein at each meal, especially when appetite is suppressed, helps protect the muscle you're working to keep.
The takeaway
GLP-1 medications work best when movement is part of the plan, not an afterthought. This study shows that declining activity is a common, measurable pattern among GLP-1 users, and the long-term health consequences of losing muscle alongside fat are real. If you want to maintain your muscle while on a GLP-1, this is a sign to intentionally build movement back into your routine.
