supersaturated with liquid—there’s more liquid in there than it can hold on to—so when you slice it open, all that extra liquid pours out By resting the steak, you allow the liquid that was forced out of the edges and into the center time to migrate back out to the edges Seems to make sense, right? Imagine a steak as a big bundle of straws, representing the muscle fibers, each straw filled with liquid As the meat cooks, the straws start to change shape, becoming narrower and putting pressure on the liquid inside Since the meat cooks from the outside in, the straws are pinched more tightly at their edges and slightly less tightly in their centers So far, so good Logically, if the edges are pinched more tightly than the center, liquid will get forced toward the middle, right? Well, here’s the problem: water is not compressible In other words, if you have a two-liter bottle filled to the brim with water, it is (nearly) physically impossible to force more water into that bottle without changing the size of that bottle Same thing with a steak Unless we are somehow stretching the centers of the muscle fibers to make them physically wider, there is no way to force more liquid into them You can easily prove that the muscle fibers are not getting wider by measuring the circumference of the center of a raw steak versus a cooked one If liquid were being forced into the center, the circumference should grow It doesn’t—it may appear to bulge, but that is only because the edges shrink, giving the illusion of a wider center In fact, the exact opposite is the case Since the center of a medium-rare steak is coming up to 125°F, it too is shrinking—and forcing liquid out Where does all that liquid go? The only place it can: out of the ends of the straws, or the surface of the steak That sizzling noise you hear as a steak cooks? That’s the sound of moisture escaping and evaporating Give That Theory a Rest So why does an unrested steak expel more juices than a rested one? Turns out that it all has to with temperature We already know that the width of the muscle fibers is directly related to the temperature to which the meat is cooked, and to a degree, this change in shape is irreversible A piece of meat that is cooked to 180°F will never be able to hold on to as much liquid as it could in its raw state But once the meat has cooled slightly, its structure relaxes—the muscle fibers widen up slightly again, allowing them to once again hold on to more liquid At the same time, as the juices inside the steak cool, proteins and other dissolved solids cause them to thicken up a bit Have you ever noticed that if you leave pan drippings from a roast to sit overnight, they are almost jellylike? This thickening helps prevent those juices from flowing out of the steak too rapidly when you slice it I cooked a half dozen steaks all to an internal ... Where does all that liquid go? The only place it can: out of the ends of the straws, or the surface of the steak That sizzling noise you hear as a steak cooks? That’s the sound of moisture escaping... once the meat has cooled slightly, its structure relaxes? ?the muscle fibers widen up slightly again, allowing them to once again hold on to more liquid At the same time, as the juices inside the. ..that is only because the edges shrink, giving the illusion of a wider center In fact, the exact opposite is the case Since the center of a medium-rare steak is coming up