Digging into Body Composition with Obesity Treatment at EASD

People have “lots of interest” in the effects of GLP-1 treatment for obesity on body composition, reports endocrinologist Daniel Drucker from EASD in Hamburg. Judging from clickbait headlines about semaglutide, we suspect public interest in this question is strong as well. So that makes data presented at EASD from the SURPASS study on muscle composition effects of tirzepatide quite interesting.

An MRI Study
of Diabetes Patients

The data for this study comes from people taking tirzepatide for type 2 diabetes. Most of them have obesity, too. These were patients in the SURPASS-3 study, in which patients had an average BMI of 33.5. A subset of the patients in that study, 296 of them, became part of the MRI studies that Jennifer Linge and Naveed Sattar presented.

The first of these two analyses showed that patients who received tirzepatide and lost significant amounts of weight did not experience unfavorable or unexpected changes in muscle composition. When people lose fat mass, they can also expect to lose some muscle mass and Linge found that this loss of muscle mass is in line with expectations for anyone losing weight – whether or not they were taking a GLP-1 agonist.

So, no. This drug does not “melt away all-important muscles” as clickbait headlines might have the public fear.

Sattar presented further analysis, which showed that tirzepatide actually reduced fat infiltration of muscle in these diabetes patients compared to patients receiving insulin degludec.

Much More to Learn

These data are quite interesting. But they do not tell us to forget about the possibility of losing muscle mass when people get treatment for obesity. They simply give us reason to think that muscle mass may be no more or less of an issue than it is whenever treating someone for obesity.

The concern is real. This is why Lilly was willing to pay up to two billion dollars for the rights to bimagrumab. This is a drug that might help people gain muscle mass and lose fat mass. So you can expect that we will learn much more about questions regarding body composition in obesity treatment.

Click here for the abstracts of these presentations. For an exploratory analysis of body composition after semaglutide treatment in obesity without diabetes, click here.

Anatomical Studies, drawing by Leonardo da Vinci / WikiArt

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October 4, 2023