GLP-1’s target “Muscle Marbling”

[Jarheadb160341]

The idea that GLP-1s lead to extreme muscle wasting is mostly overstated, since common body-composition scans like DEXA lump intramuscular fat together with total muscle mass.

Drugs such as Tirzepatide and Retatrutide have been shown to selectively attack and lower muscle "marbling" — that is, intramuscular fat, or myosteatosis

https://www.sciencedirect.com/science/article/pii/S2666379126000820

 

[Pete369]

Big calorie deficits — particularly when resistance training and adequate protein are missing — lead to muscle loss whether or not GLP1 is involved.

That being said… I guess Reta means I wouldn’t be called ‘prime’ anymore.

 

[woundcarping]

Reta is also quite effective at clearing the marbling out of the liver.

 

[Vash]

If my autopsy comes and nobody mentions my marbling, that’s going to be a problem.

 

[Shittersfull]

Every person who has just joined should go through this post.

GLP-1 drugs are associated with a phenomenon being called "muscle marbling." [[Q1]]

When fat accumulates inside muscle tissue rather than under the skin, it is described as muscle marbling. [[Q2]]

This can happen alongside rapid weight loss, and it may affect how strong and functional the muscle remains. [[Q3]]

 

[5byfive]

Jarheadb160341 said:

The idea that GLP-1s lead to extreme muscle wasting is mostly overstated, since common body-composition scans like DEXA lump intramuscular fat together with total muscle mass.

Drugs such as Tirzepatide and Retatrutide have been shown to selectively attack and lower muscle "marbling" — that is, intramuscular fat, or myosteatosis

https://www.sciencedirect.com/science/article/pii/S2666379126000820

I really don't want to come across as a downer, but this post misses the mark by quite a bit.

1) Nobody ever made that claim. When the same amount of weight is dropped over an identical timeframe, GLP-1s don't lead to greater muscle loss than doing it without them. The idea that these drugs are behind any muscle loss—much less severe muscle loss—has never been asserted by anyone.

2) The study being cited is essentially worthless. It's a pre-clinical study done on rats. If rat research actually proved anything, peptides would have wiped out every disease and none of us would ever die. Findings from rats are a fairly weak predictor of human outcomes.

 

[endlrls]

The way this idea gets pushed around is honestly mind-boggling...

Drop any amount of weight and you're going to shed some muscle.. that is, unless protein comes first and you're lifting...

I'll be chatting casually with friends or family, and without fail it's "well, you'll get skinny fat and lose muscle...."

That line comes up about as often as the "well, it's cheating to use a GLP..."

Right, because sitting at an HBA1c of 7.2 with a BMI of 34 is totally not cheating.. C'mon man...

 

[eidos]

5byfive said:

Jarheadb160341 said:

The idea that GLP-1s lead to extreme muscle wasting is mostly overstated, since common body-composition scans like DEXA lump intramuscular fat together with total muscle mass.

Drugs such as Tirzepatide and Retatrutide have been shown to selectively attack and lower muscle "marbling" — that is, intramuscular fat, or myosteatosis

https://www.sciencedirect.com/science/article/pii/S2666379126000820

I really don't want to come across as a downer, but this post misses the mark by quite a bit.

1) Nobody ever made that claim. When the same amount of weight is dropped over an identical timeframe, GLP-1s don't lead to greater muscle loss than doing it without them. The idea that these drugs are behind any muscle loss—much less severe muscle loss—has never been asserted by anyone.

2) The study being cited is essentially worthless. It's a pre-clinical study done on rats. If rat research actually proved anything, peptides would have wiped out every disease and none of us would ever die. Findings from rats are a fairly weak predictor of human outcomes.

That isn't negativity—it's critical thinking, and it happens to be 1 of the core tenets of modern science.

Biologists have been passing around a joke since the 1990s: “Modern biology has cured all diseases! ... In mice.”

Your conclusions line up with mine; nothing genuinely new emerges here. It merely offers a small bit of confirmation that there might be something worth exploring in that direction.

Clearly, this forum is unknown to them—had they known it, the user's feedback would have handed them valuable material on the topic.

What we have is an early-stage study whose purpose is to secure funding for a human trial (See the acknowledgments section of the article). In a sense, it functions as a proof of concept. Gone there, did that, and got the t-shirt.

 

[Selenium]

Jarheadb160341 said:

The idea that GLP-1s lead to extreme muscle wasting is mostly overstated, since common body-composition scans like DEXA lump intramuscular fat together with total muscle mass.

Drugs such as Tirzepatide and Retatrutide have been shown to selectively attack and lower muscle "marbling" — that is, intramuscular fat, or myosteatosis

https://www.sciencedirect.com/science/article/pii/S2666379126000820

That's a fascinating point, and it clicks for me. I had never considered that our own muscles could be marbled, despite encountering the pattern often enough on my plate

 

[dustinst22]

5byfive said:

Jarheadb160341 said:

The idea that GLP-1s lead to extreme muscle wasting is mostly overstated, since common body-composition scans like DEXA lump intramuscular fat together with total muscle mass.

Drugs such as Tirzepatide and Retatrutide have been shown to selectively attack and lower muscle "marbling" — that is, intramuscular fat, or myosteatosis

https://www.sciencedirect.com/science/article/pii/S2666379126000820

I really don't want to come across as a downer, but this post misses the mark by quite a bit.

1) Nobody ever made that claim. When the same amount of weight is dropped over an identical timeframe, GLP-1s don't lead to greater muscle loss than doing it without them. The idea that these drugs are behind any muscle loss—much less severe muscle loss—has never been asserted by anyone.

2) The study being cited is essentially worthless. It's a pre-clinical study done on rats. If rat research actually proved anything, peptides would have wiped out every disease and none of us would ever die. Findings from rats are a fairly weak predictor of human outcomes.

A rat study by itself does not establish anything for humans — that's a valid point. Still, the worry about muscle loss had real origins: many claims came from DXA scans that showed lean mass dropping. What those claims miss is that lean mass and contractile muscle are not the same thing. Newer human MRI research on tirzepatide points to a subtler story: you do lose some muscle volume (which is normal when weight comes off), yet intramuscular fat — the "marbling" — falls by even more than you'd predict, and that could mean better muscle quality. My read of the evidence is that the original "GLP-1s destroy muscle" framing was likely blown out of proportion, rather than muscle being completely unaffected.

The SURPASS-2 MRI study strikes me as the more compelling data. Rather than using DXA, it turned to MRI for measuring muscle composition. Results showed tirzepatide users lost some muscle volume (about what their weight loss would predict), but their intramuscular fat ("muscle marbling") dropped by more than anticipated. According to the authors, this might reflect an improvement in muscle quality.

 

[chewonmysac]

Before dropping 108 lbs, I’m fairly certain a cross-section of me would have resembled a Wagyu Prime Rib. These days, I’m a skirt steak.

 

[Skidude]

chewonmysac said:

Before dropping 108 lbs, I’m fairly certain a cross-section of me would have resembled a Wagyu Prime Rib. These days, I’m a skirt steak.

I was chilling in the AC, enjoying gourmet food, and having beer as well..

Maybe I qualify!

Wagyu farming is an extremely intentional, years-long endeavor aimed completely at producing delicate, lace-like fat spread (marbling) across the meat: [1, 2]

• • Diet and Appetite: The cattle receive a gourmet, energy-dense feed made of barley, corn, rice, and wheat bran. Certain farmers give beer or mild alcohol to boost the cows' appetites while they are being fattened. [1, 2, 3]
  • Stress-Free Environment: Cows are frequently housed in climate-controlled individual stalls, where classical music may be played to keep them calm.

 

[amosmylove]

If a plane crash ever leaves us stuck somewhere far from civilization, I'll be sure to tell any cannibalistic islanders they'd be getting a poor cut of meat — my marbling is low.