There has been a concern that there is a significant muscle loss when you are on GLP-1s. A new paper published in JAMA this week plays down that concern. The paper states that:

1. It is unlikely that the decline in SMM (muscle mass) that occurs with even large amounts of weight loss impairs physical function.

2. People with obesity generally have greater amounts of FFM (fat-free mass) and SMM than lean people, so the decrease in SMM induced by weight loss represents a small fraction of total body SMM.

3. Even though the decrease in SMM can sometimes cause a decrease in muscle strength, it does not necessarily have an adverse effect on physical function. Intentional weight loss causes a greater relative decrease in body fat than FFM or SMM, so the ratio of FFM/SMM to fat mass increases. Accordingly, physical function and mobility improve after weight loss despite the decrease in FFM/SMM, even in older adults with decreased FFM and SMM at baseline.

4. In addition, weight loss improves the “quality” of remaining muscle by decreasing intramyocellular and intermuscular triglycerides and increasing muscle insulin sensitivity.

5. The recent concern that marked weight loss induced by GLP-1–based antiobesity medications can cause physical frailty or sarcopenia is not supported by data

 

(The author of the study is a consultant for Eli Lilly)