People trying to save time making dinner have turned supermarket prepared foods into a 29-billion dollar per year business. But Consumer Reports says to be wary. Those foods aren’t required to have nutrition labels, and you might be consuming more fat, calories, and sodium than you think.

Consumer Reports’ secret shoppers purchased dozens of popular prepared foods from six major supermarkets and had them analyzed for sodium, calories, fat, and saturated fat.

One thing they found lots of is sodium. A mini turkey meatloaf packed an average of 891 milligrams in a 6-ounce serving. And one cup of a healthy-looking orzo salad averaged 938 milligrams.

Without a nutrition label, you’d never know that a 6-ounce serving of parmesan-encrusted tilapia fish at one store had 19 grams of fat.

Another surprising ingredient: Sugar added to a chicken parmesan meal. And mashed potatoes made with a preservative called sodium benzoate and disodium pyrophosphate to maintain color.

It turns out that many supermarkets don’t actually make all of their prepared foods. According to the clerks who were quizzed by Consumer Reports’ secret shoppers, only about half of what was tested was actually made on-site.

And you pay a price for convenience. Some of the foods Consumer Reports checked out cost twice the price of making them at home.

Consumer Reports did find one great deal: rotisserie chicken. It’s often far cheaper to buy it at the supermarket than to cook one yourself.

Consumer Reports’ survey of its subscribers found they’re happiest with the prepared foods at Wegmans, Publix, Costco, Fresh Market, and Whole Foods Market.