Label loopholes.

Don't tell us you were foolish enough to expect "lowfat 2%" milk to be low in fat. Don't you know that the dairy industry has friends in Congress? They conveniently exempted milk from the new labeling law.

Okay. So people will assume that it's got only three grams of fat in a glass--that's the new rule for "low-fat" -- when it really has five grams. What's the big deal?

Three of those five grams are saturated fat. And for each gram of sat fat that every American cuts back on, a quarter of a million fewer people will develop heart disease.

So what if "lowfat 2%" milk is as popular as whole milk, partly because people think it's low in fat? What's good for the dairy industry is good for... well, the dairy industry.

At first glance, it looks like the Chunky Chips Ahoy have less fat than the originals. Look again. Chunky's serving size is only one cookie that weighs 17 grams. The original's serving size is three cookies that weigh 32 grams (about an ounce). Ounce for ounce, they're equally fatty. Weren't the new labels supposed to end serving-size trickery?

Yes they were, and yes they do. The FDA set "reference" serving sizes for all foods, based on what people typically eat. Almost all cookies, for example, have to use one ounce. And claims like "low-fat" are only allowed if they're valid for the reference serving. The Chunky Chips Ahoys are an exception because they're so big.

Here's the rule: Any food that comes in a "unit" (like a slice of bread, a roll, or a muffin) can use a single unit as a serving if that unit weighs at least one-half of the reference serving. That makes sense, because people don't eat fractions of cookies, slices of bread, etc.

The bottom line: Check the serving size. If it's not what you eat--or not the same on two foods you're comparing--adjust accordingly.

Catch that "Made with Fruit" on the label? It's all over the supermarket these days, in part because companies are trying to cash in on advice from the National Cancer Institute to eat "5 A Day" (fruits and vegetables, that is).

Only one problem: some foods don't have much fruit. There are no more than two grapes--and no other fruit at all--in each pouch of these glorified Gummi Bears. The rest is sugar.

The new labeling rules don't address most claims about an ingredient, like fruit, bran, or whole wheat. So beware.

Oscar Mayer's Healthy Favorites Cooked Ham has 620 mg of sodium per serving. Budget Gourmet's Light and Healthy Oriental Beef has 950 mg..and nine grams of fat. That's healthy?

Last May, the FDA issued new rules that limit the fat, saturated fat, cholesterol, and sodium in foods that are labeled "healthy." The rules are reasonable...mostly.

For example, most foods have to qualify as "low-fat" and "low-saturated-fat" before they can be called "healthy." Problem is, to be called "low-fat," meals and main dishes have to meet very loose criteria.

And because so many foods now labeled "healthy" are sodium-laden, the FDA is phasing in limits:

* By January 1, 1996, "healthy" individual foods must have no more than 480 mg of sodium per serving (meals and main dishes can't exceed 600 mg).

* By January 1, 1998, "healthy" individual foods must have no more than 360 mg of sodium (meals and main dishes can't exceed 480 mg).

The bottom line: Look for "healthy" foods, but don't assume that they're all rock-bottom low in fat and sodium. Shop around. And watch out for "wholesome," "smart," and similar terms. They can mean almost anything.

Corn syrup, sugar, peppermint oil, and colors are the only ingredients in these candies. So how come the "Sugars" number on the label is only about half of the "Total Carbohydrate"? The mints have no carbohydrates other than sugar.

What's up? A pesky little problem with corn syrups, that's what. Only about a third of the sugars in some corn syrups show up as "sugar" on the laboratory tests that analyze foods. So products that contain corn syrup may appear to be much lower in sugar than they are.

And while some corn sugars get left out of "Sugars," natural sugars in milk and fruit are included. Oh well. It's better than nothing.

What food adds the most saturated fat to the average American's diet? Red meat.

What food doesn't have to have a "Nutrition Facts" panel on its package? You guessed it. (Neither does fresh poultry, fish, fruits, or vegetables.)

Congress decided that if 60 percent of supermarkets voluntarily provide "Nutrition Facts" for those foods, it won't require labels. But, aside from the fact that your supermarket could be one of the 40 percent that don't, there are three catches.

First, the information could be stuck on a sign or in a looseleaf binder. Second, it can (and you bet it will) omit the crucial % Daily Values. And third, the serving size is a skimpy three ounces.

"No cholesterol," boasts the label. Swell. Sounds like this stuff won't raise your blood cholesterol one iota.

Wrong.

Oreos are made with "partially hydrogenated oil." That means they contain trans fat, which raises cholesterol about as much as saturated fat does. The FDA doesn't count trans fat as saturated, although CSPI recently asked it to.

The FDA has wisely limited the saturated fat in foods that make "no cholesterol" claims to no more than two grams per serving. But if you add Oreos' trans fat to its sat fat, it's got three grams of artery-clogging fat.

Until the FDA starts treating trans fat as saturated, assume that the "saturated fat" number is an underestimate in foods that are made with partially hydrogenated oils. How much of an underestimate you usually can't tell, but here are some tips:

* If the food is "low-fat," there's too little trans to worry about.

* If a label lists "Monounsaturated Fat" and "Polyunsaturated Fat" as well as "Saturated Fat," you can add the three and subtract them from the "Total Fat" to get a rough estimate of how much trans the food contains. (It's rough because the numbers probably have been rounded.) In this case, three Oreos have about two grams of trans fat.