Pizza on earth.

Want to get into the frozen pizza business? Just make sure you put some meat in your toppings. That way you'll be regulated by the U.S. Department of Agriculture, not the Food and Drug Administration.

And as any pizza-maker worth his pepperoni knows, when you're in USDA territory, you can pretty much say what you want on your labels.

* Want to tout your not-lowfat pizza as 92 per cent fat-free"? No problem.

* Want to put a picture of melted cheese on your box even though 90 percent of the "cheese" in your pizza is imitation? Hey, that's your business.

* Want to throw on some cheap flavor (read salt') without letting on how much? That's cool.

In fact, there's not much that isn't cool with the folks over at the USDA Uniformly Slack in Demanding Accountability?). And that explains, at least in part, why a stroll down your supermarket's frozen-pizza alley can be so frustrating.

But there are pizzas worth eating. There's even a great-tasting one that's made math whole wheat flour and no cheese. There are some real duds, too. Here's how to tell which are which:

1. Pay no attention to per-serving information.

According to the boxes, a serving of Weight Watchers Deluxe Combination Pizza contains 10 grams of fat, while a serving of Soypreme French Bread Pizza contains four grams. Yet the Weight Watchers is no fattier than the Soypreme.

What gives?

Weight Watchers assumes you're going to eat its entire 7.15-ounce pizza, while Soypreme says you're only going to eat one of the two french bread pizzas in its 9.5-ounce box.

The best way to avoid serving-size problems like this is to look at what percent of a pizza's calories come from fat. That doesn't depend on the arbitrary serving size the manufacturer chooses.

That's what we've done in our chart, which shows that both the Weight Watchers and the Soypreme pizzas get 24 percent of their calories from fat.

As for sodium, here's one way to avoid being tricked by unrealistically small serving sizes: If the number of milligrams of sodium in a serving is more than 1 1/2 times the number of calories in that serving, the pizza's too salty.

(Actually, your overall diet should contain no more than I mg of sodium for every calorie you eat, but you can balance the saltier foods-like pizza-with low-salt foods like fresh fruits and vegetables.)

This sodium rule of thumb also sets a tougher standard for lowfat (low-calorie) pizzas than for fattier ones, but our criteria for Best Bites eliminates the fatties anyway.

Of course, all of this is meaningless if you can't find the numbers you need. Schwann Sales Enterprises, whose three brands (Tony's, Red Baron, and Kidstuff) account for 15 percent of the frozen-pizza market, doesn't put nutrition information on its packages.

The company did give us the numbers, but told us they were copyrighted and that we couldn't publish them. We don't buy that. But while our lawyer is arguing with their lawyer, we can tell you this: if you did see those numbers you'd understand why they're not on the label.

(If you want to tell Tony's, etc. that keeping a public interest group from publishing nutrition info isn't nice, call them at 800-544-6855.)

2. Don't believe label claims.

According to the label, Tombstone's Light Pepperoni 8-inch Pizza is "92% Fat Free." But that's not the same as saying it's lowfat. The pizza gets 35 percent of its calories from fat, and its 15 grams of fa in a six-ounce serving is far more than the FDAs proposed limit of two grams for a low-fat food.

3. Check the ingredient list. Here's what to look for:

* Reduced-fat cheese. Weight Watchers, Tombstone Light, and (hold your mozzarella, folks) Domino's home-delivered are among the growing number of pizzas that use part-skim cheese. They taste as "cheesy" as the full-fatties.

* Tofu. It's a "cheese" made from soybeans. Most lowish-fat pizzas use it instead of mozzarella. It has no cholesterol and far less artery-clogging saturated fat.

Unfortunately, some pizza makers haven't quite gotten the knack of making it look and taste like cheese. Of the tofu-topped pizzas we tasted, only Soypreme French Bread Garden Patch wasn't glompy and glue-like.

* Whole wheat flour. A six-ounce serving of some of the crustier home-delivered pizzas has more than six grams of fiber, which is more than a fifth of the 20 to 30 grams of fiber you should eat in an entire day. But that's just because they contain so much white flour.

Of course, whole-wheat-flour crust is higher in fiber ... and healthier. Just don't expect it to taste light. Soypreme and Au Naturel French Bread Pizzas did, but Old Chicago Pizza-lite and Soypreme Whole Wheat Cheese Style tasted like prechewed cardboard.

* Vegetable toppings. The more vegetables, the better. But some companies (like Domino's) dump extra cheese on their veggie pizzas. Tell the telephone order-taker not to. Lorraine Jones compiled the information for this article.