Does searing meat seal in the juices?
No. It is one of the most persistent cooking myths, it was tested and disproved well over a century ago, and searing is still worth doing — for an entirely different reason.
Where the myth came from. The German chemist Justus von Liebig proposed in the 1840s that browning the exterior formed a seal trapping the juices inside. It sounded plausible, was repeated by influential cookery writers including Escoffier, and entered the canon.
Why it is wrong. A seared crust is not waterproof. You can observe this directly: a seared steak continues to sizzle and release moisture throughout cooking, and juices run out when it is cut. Harold McGee and others have demonstrated experimentally that seared meat loses as much or slightly more moisture than unseared meat cooked to the same internal temperature — partly because searing adds energy and drives evaporation.
What searing actually does. The Maillard reaction — a set of reactions between amino acids and reducing sugars at high temperature — producing hundreds of aromatic compounds and the brown crust. This is flavour creation, not moisture retention, and it is a substantial contribution: the difference between a seared and an unseared steak is enormous in taste and almost nil in juiciness.
What actually determines juiciness:
Final internal temperature, by a wide margin. Moisture loss rises steeply as muscle proteins contract and squeeze water out, which happens progressively with temperature.
Cut and fat content.
Salting in advance, which helps proteins retain moisture.
Resting, allowing the meat to relax so less liquid runs out when cut.
The practical consequence. Since searing does not seal, the order does not matter for moisture. This is why reverse searing works so well: cook gently to just below target temperature, then sear briefly at high heat. You get an even interior without a grey overcooked band, and a proper crust.
For a good sear: a very hot, dry pan; a dry surface, since water must boil off before browning begins; not overcrowding; and accepting the smoke.