What Are GLP-1 Receptor Agonists?
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GLP-1 receptor agonists (GLP-1RAs) are medications originally designed to help manage type 2 diabetes. Over time, they’ve also gained popularity for helping people lose weight. Popular examples include liraglutide, semaglutide, and tirzepatide.
These drugs work by mimicking a natural hormone in the body called GLP-1. This hormone helps control blood sugar and makes you feel full, so you eat less.
Weight Loss Is Good, But What About Muscle?
While GLP-1RAs help people lose weight—mostly fat—that weight loss can sometimes include muscle too. This is important because muscle plays a big role in your health. It helps control blood sugar, keeps you strong, and supports long-term weight maintenance.
Losing too much muscle, especially in older adults, can lead to a condition called sarcopaenia. This condition includes low muscle mass and reduced strength and can raise the risk of falls, frailty, and other health issues.
What Does the Research Say?
Animal studies show promising results. In rodents, GLP-1RAs have been found to reduce inflammation in muscles, improve mitochondrial health (which supports energy), and even protect against muscle loss. These effects suggest that these drugs might be good for muscle health.
However, human studies show mixed results. Some studies report a significant drop in fat-free mass (which includes muscle), while others show only a small effect on muscle or even some protective benefits.
Muscle Mass vs Muscle Strength
It’s not just about how much muscle you have, but how well it works. Strength and function matter too. Some studies have shown that even if a bit of muscle mass is lost, people still maintain their physical abilities like walking speed or grip strength.
This means that the small decrease in muscle may not always be harmful—especially if muscle quality improves or fat within the muscle is reduced.
Are Some People at Higher Risk?
Older adults, people with chronic diseases (like heart failure or kidney disease), and those who are frail may be more likely to develop sarcopaenia. For them, losing muscle during weight loss could be risky.
Doctors should be cautious when prescribing GLP-1RAs to these patients and may need to monitor their muscle health closely.
How to Protect Muscle While Losing Weight
Fortunately, there are ways to reduce muscle loss:
- Exercise regularly especially strength training
- Eat enough protein to support muscle maintenance
- Consider supplements if you're older or not eating well
Combining GLP-1RAs with a healthy diet and exercise program can help protect your muscles while still losing fat.
Final Thoughts
GLP-1RAs are effective weight-loss tools and may even help improve muscle health in some ways. However, more research is needed to fully understand their impact on muscle mass and function, especially in humans.
If you’re using these medications, talk to your doctor about how to protect your muscles. Focus on a balanced approach that includes good nutrition and physical activity.
Keeping your muscle strong is just as important as losing the fat.