Muscle “marbling”: Good in steak, bad in our bodies

Consider the delicate web of fat in a Wagyu steak. The “marbling” that makes carnivore connoisseurs swoon is a visual heuristic for quality flavor.

Now, a new study suggests the very same marbling of fat inside our own muscles points to trouble.

This condition, known as intramuscular adipose tissue, or IMAT, has long been recognized by scientists as a strong indicator of poor health. It’s linked to a wide range of diseases: obesity, Type 2 diabetes, neuromuscular disorders (including Duchenne muscular dystrophy) and neurogenerative conditions such as ALS. In some cases, clinicians can even track the progress of a disease by the amount of fat in muscle tissue.

“We wanted to understand the precise function IMAT might play on muscle health,” said Daniel Kopinke, Ph.D., an associate professor in the department of pharmacology and therapeutics in the UF College of Medicine. “Now, we have functional evidence that it is an active driver of declining muscle function.”

The study shows that intramuscular fat acts as a physical barrier, obstructing the traditional healing process and regeneration that typically follows a muscle injury.