Subway’s slogan is “Eat Fresh” –but order the Grilled Chicken Breast and Baby Spinach Salad, and you’ll get defrosted, precooked chicken strips that have been mechanically branded at a factory to look like they’re hot off the grill. Which isn’t quite the same thing.

Americans love grilled chicken, a low-fat protein source recommended by everyone from Atkins to the American Heart Association. But fast-food restaurants shun actual grilling like the plague. Rather than install expensive equipment and pay for a dedicated chef, most chains outsource the cooking to giant processors such as Tyson, Pilgrim’s Pride, and Keystone Foods.

And the brave new world of industrial grilling is a wee bit different from firing up the Weber in your backyard. First, naturally low-fat, low-sodium chicken breasts are submerged in a giant “tumble marinator” and saturated with a hearty brew of salt, oil, sugar, chemicals, and fat. Burger King’s Tendergrill fillet contains added chicken fat and more than 30 other items. McDonald’s Grilled Chicken fillet has up to 20% “solution” by weight. The chicken in Panera Bread’s Chicken Salad Sandwich includes beef extract, for extra chicken-y goodness.

In a typical factory, the fattened-up breasts are dumped onto a conveyor belt moving at about nine inches per second, where a crack squad of sous chefs lovingly positions each breast on its own patch of real estate. This process, known in the trade as “spreading,” is the sole personal touch on a 100-foot-or-so automated cooking line. Next, the evenly spread breasts roll under a press and into a long stainless-steel “impingement oven,” which bakes the chicken with jets of hot air. Convection cooking, as opposed to actual grilling over an open flame, provides the highest “yield,” retaining the marinade and maximizing the weight of the final product.

To create the “appearance that the product may have been cooked on a backyard grill,” the newly baked chicken fillets are often branded with “char marks,” explains Jan Gaydos, director of marketing at FMC FoodTech, a manufacturer of industrial cooking equipment. The company’s CM-40 II Charmarker uses red-hot branding wheels to burn grill marks onto the surface of chicken breasts as they emerge from the oven. FMC’s Charmarker can work a lot faster than a short-order cook, grill-marking a row of breasts in about a second, before they hit the freezer. (A Subway spokesman says the char-marking “enhance[s] the appearance and appeal of the product.”)

Char-marking is a big business. Pilgrim’s Pride runs 45 lines in 10 factories to produce 2 billion pounds of cooked chicken per year. Asked whether it char-marks for fast-food chains, vice president of marketing Dan Emery says, “They don’t really like us to name names, but we do 9 of the top 10, all except McDonald’s.”

In fact, the only chain we could find that actually grills chicken in the restaurant is Chick-fil-A, whose Chargrilled Chicken Sandwich is the rare fast-food offering that approaches the nutritional benefits of home-grilled chicken breasts. As for the rest, well, it’s not exactly diet food. But it does look terrific.