Fascinating article on the latest understanding of how weight training increases fat loss. At a cellular level muscle cells, post activity, tell fat cells to metabolise by sending snippets of RNA out into the body, which fat cells pick up and react to.
https://www.nytimes.com/2021/07/21/well/move/weight-training-fat.html?smtyp=cur&smid=fb-nytimes
They noted plenty. Before their improvised weight training, the rodents’ leg muscles had teemed with a particular snippet of genetic material, known as miR-1, that modulates muscle growth. In normal, untrained muscles, miR-1, one of a group of tiny strands of genetic material known as microRNA, keeps a brake on muscle building.
After the rodents’ resistance exercise, which consisted of walking around, though, the animals’ leg muscles appeared depleted of miR-1. At the same time, the vesicles in their bloodstream now thronged with the stuff, as did nearby fat tissue. It seems, the scientists concluded, that the animals’ muscle cells somehow packed those bits of microRNA that retard hypertrophy into vesicles and posted them to neighboring fat cells, which then allowed the muscles immediately to grow.
But what was the miR-1 doing to the fat once it arrived, the scientist wondered? To find out, they marked vesicles from weight-trained mice with a fluorescent dye, injected them into untrained animals, and tracked the glowing bubbles’ paths. The vesicles homed in on fat, the scientists saw, then dissolved and deposited their miR-1 cargo there.
Soon after, some of the genes in the fat cells went into overdrive. These genes help direct the breakdown of fat into fatty acids, which other cells then can use as fuel, reducing fat stores. In effect, weight training was shrinking fat in mice by creating vesicles in muscles that, through genetic signals, told the fat it was time to break itself apart.
“The process was just remarkable,” said John J. McCarthy, a professor of physiology at the University of Kentucky, who was an author of the study with his then graduate student Ivan J. Vechetti Jr. and other colleagues.