How do diners keep their burgers from shrinking so much? I usually buy Ground Sirlion, nut when I make burgers they tend to end up way smaller than the bun!!!

well, the uncooked burger size is larger than the bun before they cook it and it shrinks to the size of the bun.

It's the fillers, kitty! When I make burgers, I use ground beef, eggs, Lipton's Onion Soup Mix, some bread crumbs too, and maybe ketchup or HP sauce - depends.

The added liquids and mealy stuff makes the difference.

Several things take place at a restaurant, depending on if its fast food or if it is "formal" dinning.

Fast food produces frozen patties which are up-to 1/2 again the diameter of the bun uncooked. Some places will place a weight on top of it while cooking (like a bacon iron) to keep the thin patties flat.

Fine Dinning will use a leaner ground beef, make a patty which is about 1/4 the size of the bun uncooked. Most use a real grill and flame, some don't.

Here at my place, I mix a package of lean ground beef (about 1/2 pound) with an egg, about 2-3 tablespoons of oats, worcestershire sauce, and various other herbs and spices (depending what strikes my fancy that night) and a sprinkle of ground up crackers (saltines) to make a mixture which has more volume, sticks together when Mixed well, made into balls then patted down to about 1/4 inch thick. I make mine about 1/4 again the diameter of the bun

Then I use a hot pan to scorch the outside, flip brown again, then turn down the heat and slow cook to get the interior.

Any excess liquid is absorbed by the oats. My Hamburger patties ate about 1/2 inch wider than the bun, having the look of fullness

You can substitute the Oats with minute rice, or cracker crumbs, or bread crumbs. All add flavor, density and make it appear that you have more meat.

Thank you guys....now on the fourth I can have a nice sized burger!!!