Fat: fine-tuning the message.

"You can never be too rich or eat too little fat, right? Wrong..." said the wire story last November.

That's when a study from the University Washington suggested that eating too little fat could increase the risk of heart disease.

Fat's in the fire ... again.

Last August, the influential New England Journal of Medicine published a debate asking: "Should a low-fat, high-carbohydrate diet be recommended for everyone?"

In January, Harvard University co-sponsored a conference on fat. On the agenda: "Should recommendations on the amount of total fat be eliminated?"

If it sounds like another flip-flop is in the works, relax. No one is recommending the typical pizza-burgers-fries-steaks-and-fried-chicken high-fat American diet.

The big "debate" may amount to no more than tinkering with a diet that everyone agrees is healthy.

"So good ... can we ever make enough?" ask the TV ads for SnackWell's fat-free Devil's Food Cookie Cakes.

"It's just perfect," say ads for Haagen-Dazs Low Fat Ice Cream.

Now that the airwaves, the supermarkets, and our refrigerators are flooded with low-fat foods ... now that fat-free and low-fat milk take up as much room as whole milk in the supermarket dairy case ... now that grilled chicken sandwiches sit proudly next to the burgers in fast-food restaurants ... now researchers are scratching their heads and mulling over whether fat is bad?

It's enough to make you tear up your coupons for low-fat Ben & Jerry's and make a reservation at the Outback Steakhouse.

Don't. Here's what the latest fat debate is not about:

* Saturated fat. Everyone agrees that it raises the risk of heart disease and possibly colon and prostate cancer. So meat, cheese, pizza, ice cream, whole and 2% milk, butter, and most pies, cakes, and pastries are still in the doghouse.

* Trans fat. It's formed when oils are partially hydrogenated to make more-solid fats like margarine and shortening. Evidence continues to mount that trans raises blood cholesterol about as much as sat fat does (though we eat less of it). So there's no green light for most french fries, fried chicken or fish, doughnuts, cakes, pies, and pastries.

* Fruits, vegetables, beans, and whole grains. There's universal agreement that Americans need to eat more fruits and vegetables to cut the risk of cancer, heart disease, and stroke. There's some debate over how much carbohydrate-rich grain (bread, cereal, pasta, rice, etc.) to eat, but not over whether it should be whole rather than refined.

What's still up for grabs? Unsaturated fats.

They may be monounsaturated or polyunsaturated. They're found primarily in oils (olive, canola, corn, soy, safflower, sunflower, etc.), salad dressing, nuts, and mayonnaise.

The question is: After you get the basics of a healthy diet--enough fruits, vegetables, whole grains, low-fat dairy, and fish, poultry, or beans--do you spend your remaining calories on unsaturated fats or on more carbohydrates like bread, pasta, and cereal?

At one extreme are the very-low-fat Pritikin and Ornish diets. Both ban all added oils--you "saute" vegetables in broth, eat your bread unbuttered, and adorn your salad with only fat-free dressings. That leads to a diet with only ten percent of calories from fat.

At the other extreme is a true Mediterranean diet like that eaten on the Greek island of Crete 50 years ago. Olive oil (plus some nuts and olives) put the fat at about 40 percent of calories.

Most experts ignore the extremes. Their question: Is longstanding advice--to shoot for less than 30 percent of calories from fat--ideal? The debate boils down to a few key issues.

Heart Disease

How can anyone doubt whether a low-fat diet helps prevent heart disease? Haven't they heard of Nathan Pritikin and Dean Ornish?

Pritikin showed that a very-low-fat diet chock full of fruits and vegetables, whole grains, and beans could slash blood cholesterol.(1) Using X-rays called angiograms, Ornish showed that after one year, a similar diet could start unclogging arteries.(2)

But Ornish and Pritikin didn't just cut the fat. They got their patients to exercise and lose weight (among other things). What if people just ate a rock bottom low-fat diet?

That lowers LDL ("bad") cholesterol. But if you don't lose weight and step up your exercise, it also lowers HDL ("good") cholesterol. The question is: Does that matter?

"In a high-fat culture like ours, a low HDL correlates with heart disease," explains William Connor of the Oregon Health Sciences University in Portland. "But there are no good data showing that a low HDL is harmful if you're eating a low-fat diet."

Think of it this way: HDL protects you from a high-fat diet. But if you ate very little fat, you might not need so much protection.

"There are societies with low HDL that are doing fine," says Alice Lichtenstein of the Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University in Boston.

She and others point out that those countries aren't proof that low HDL is harmless.

"You have to ask what else populations with low HDL are doing," says Frank Sacks of the Harvard Medical School.

"They're active and lean, they don't have diabetes, and they have low LDL. So other things may counterbalance their low HDL to make their total package of risk low."

The bottom line: HDL is only part of the picture. Ornish's diet and exercise plan cut HDL, but it still helped unclog arteries.(3) And when Lawrence Rudel of the Bowman Gray School of Medicine in Winston-Salem, North Carolina, fed monkeys a diet very high in monounsaturated fat instead of saturated fat, their HDL stayed high ... but their arteries got clogged anyway.(3)

"It's premature to recommend a high-mono diet," says Rudel. To really answer the question, researchers should put people on a low-fat or a high-unsaturated-fat diet, wait several years, and use angiograms to check their arteries.

In the meantime, don't fret over the recent report that cutting back on fat causes stroke. The study was severely flawed (see "Fat & Stroke," p. 13).

Weight Loss

Sales of SnackWell's haven't skyrocketed just because snackers are worried about their arteries. Millions of people think that a low-fat diet will keep them lean. Will it? The answer depends on which low-fat diet you're talking about.

To many researchers, "low-fat" is shorthand for meals that are packed with fruits, vegetables, and other foods that fill you up without supplying many calories. It's not clear whether that kind of healthy low-fat diet helps keep people lean (see "Cut Fat, Lose Weight?").

But to many people, a "low-fat" diet doesn't mean cantaloupe and carrot sticks. It's an invitation to an all-you-can-eat buffet of high-calorie foods like fat-free cakes, cookies, ice cream, and chips.

"Public health experts recommended low-fat foods, but people added cookies and brownies, not fruits and vegetables," says Lichtenstein.

The food industry hasn't helped. Ads push fat-free sweets, not fat-free fruits and vegetables.

"It's the commercialization of the low-fat diet," says Sacks. Countries with low rates of heart disease like rural China or Japan, he explains, traditionally ate diets that are very high in rice, vegetables, and fish.

"In the U.S., a low-fat diet is high in sugar, white bread, pasta, crackers, and baked goods. That's different from the diets that inspired Ornish and Pritikin."

If you're going to eat a brownie, you're better off eating a fat-free one than a full-fat one. But the ads imply that "fat-free" on the package means "fat-free" on your thighs, no matter how many you swallow.

"Until recently, people who were concerned about their figures would never eat brownies," says Lichtenstein. Now they eat a whole package because the label says "fat-free."

When it comes to weight loss, the bottom line is really an old message: "Calories count," says Walter Willett, head of the nutrition department at the Harvard School of Public Health.

And it's not just the calories you eat that count. Everyone agrees that America will never crack its obesity epidemic if we don't get moving.

"We've got to tell Americans to get off their rear ends and exercise," says UCLA researcher James Barnard, who has studied 4,500 people on the Pritikin diet.

How Much Fat?

Couch potatoes who pig out on low-fat sweets, white bread, and other carbohydrates might lower their HDL and outgrow their wardrobes. So why not keep saturated fat low, but replace some carbs with unsaturated fats? That might keep HDL up, but researchers are worried that the strategy could backfire:

* Obesity. High in fat means high in calories. Ounce for ounce, fat has more than twice the calories of protein or carbohydrate.

"We don't have a prayer of dealing with the growing obesity problem in this country if we say there's nothing wrong with eating fat," says heart disease expert Jeremiah Stamler, who is professor emeritus at Northwestern University in Chicago. And if people gain weight on a high-unsaturated-fat diet, their HDL will slide downwards.

"In a society that expends little energy on physical activity at home or on the job, calorie needs aren't high," he adds. "So if the diet is high in fruits, vegetables, beans, and whole grains, there is no room for adding lots of oil."

* Crowding out nutritious foods. Oils have no minerals or vitamins (except E). That's not much to offer for 120 calories per tablespoon.

And what does the unsaturated fat replace? "If you're eating more fat calories, you're eating fewer plant foods, fewer antioxidants," says William Connor. "If you soak your whole wheat bread in olive oil, you have to eat less bread, unless you want to gain weight."

When we converted a "Low-Fat Menu" to a "High-Unsaturated-Fat Menu" with the same number of calories, we gained vitamin E, but we lost some fiber, zinc, iron, and other minerals (see "Foods, Not Fats").

* Confusion. If people have misinterpreted the "eat less fat" message, imagine what they'll do with "eat less saturated and trans--but not unsaturated--fat."

"In our society, with our food supply, unless we tell people to moderate fat, they'll eat too much saturated fat," says Lichtenstein. "The last thing we want is to have people drizzle olive oil on their hot fudge sundaes."

Researchers may talk about a largely vegetarian Mediterranean-like diet with added oil and nuts but little meat or dairy. But that's not what they're selling at Burger King, Pizza Hut, KFC, or Baskin-Robbins.

"Americans aren't going to eat 40 percent of their calories from olive oil," says Connor. "They're used to the invisible--and harmful--fats in meat, dairy, and eggs."

* Blood clots. "The consumption of a high-fat meal might contribute to clot formation," says Lone Frost Larsen of the Royal Veterinary and Agricultural University in Denmark. And a blood clot "may cause a heart attack by blocking an artery."

When Larsen fed 18 men high-fat meals, the men had higher levels of blood clotting factors than after they were given low-fat meals.(4) If didn't matter whether they ate olive oil or butter, she adds. "There is no difference in the type of fat you eat."

The risk of blood clots might not be a problem in people whose arteries are clean as a whistle. But this is a nation with a McDonald's on every street corner. "In a society that's prone to atherosclerosis," says Stamler, "high-fat meals may promote blood clots that cause heart attacks."

What to Eat

You could get awfully hungry waiting for scientists to finish the fat debate. In the meantime, the most sensible strategy is to eat a DASH-like diet (see "Foods, Not Fats").

It's not as low in fat as Pritikin's or Ornish's diets. People who eat--or should eat--about 2,000 calories a day get two to three small daily servings of unsaturated fats (like salad dressing, oil, mayo, and soft margarine) plus some nuts several times a week.

Those fats can help keep HDL high. And most are good sources of vitamin E, which may help prevent heart disease.

"The dominant message has been that you can load up on potatoes and pasta and that you should cut out salad dressing and nuts," says Willett. "The fat phobia has spilled over to healthy fats."

But that's not a license to add oil as though its calories don't count.

Says Lichtenstein: "I wouldn't want to give people the impression that they should pour extra oil on their salads, because I don't want to add calories without taking some out somewhere else."

(1) Arch. Intern. Med. 151: 1389, 1991.

(2) Lancet 336: 129, 1990.

(3) N. Eng. J. Med. 338: 127, 1998.

(4) Arterioscler. Thromb. Vasc. Biol. 17: 2904, 1997.

RELATED ARTICLE: CUT FAT, LOST WEIGHT?

Does a healthy low-fat diet automatically lead to weight loss? Yes. "But over the long term, the loss virtually disappears," says Harvard's Walter Willett. He cites half a dozen studies in which people who reported eating lower-fat diets lost only about two to six pounds after a year.(1)

But others argue that those studies aren't the final word:

* Wrong studies. "A lot of studies address whether people spontaneously lose weight on a low-fat diet," says Susan Roberts of the USDA Human Nutrition Research Center on Aging at Tufts University.

"But an equally important--or better--question is whether consuming low-fat diets will help people lose weight if they try to."

What's more, clinical trials that compare weight loss on high- vs. low-fat diets haven't mimicked real world temptations. "No one has used McDonald's, Dunkin' Donuts, and the other foods we typically overeat," she adds.

* Five pounds may matter. "That people spontaneously lose any weight just by switching to a low-fat diet is amazing," says Arne Astrup of the Royal Veterinary and Agricultural University in Denmark. "Weight loss of three kilograms [6.6 pounds] could decrease the prevalence of obesity from 27 to 14 percent of the population."

* The diets weren't really low-fat. In most long-term studies, people on a "low-fat" diet reported eating about 20 to 30 percent of their calories from fat.

"They didn't cut fat enough," says UCLA's James Barnard. Would people have lost more weight if they had gotten down to 10 or 15 percent? No one knows.

* Low-fat diets may prevent weight gain. Weight loss is only one side of the coin. It's also possible that low-fat diets make it easier for people to avoid gaining weight.

Astrup studied 37 obese people who lost an average of 28 pounds.(2) He told half to limit their calories and half to limit their fat intake. "After two years," says Astrup, "the group on the low-fat diet gained back less weight."

It's one thing to say that the right studies on the right low-fat diets may prevent weight gain or promote weight loss. It's another thing to do a number of those studies and see what happens. So far, no one has.

In the meantime, people who want to lose weight shouldn't just watch fat. Says Willett: "The focus on fat distracts people from dealing with the real causes of obesity--too many calories and too little exercise."

(1) N. Eng. J. Med. 337: 562, 1997.

(2) Brit. Med. J. 314: 29, 1997.

RELATED ARTICLE: THE BOTTOM LINE

* Eat a healthy lower-fat diet, like the DASH diet or a vegetarian version of it (see "Foods, Not Fats").

* If your HDL ("good") cholesterol is low (35 or less), add a daily serving or two of canola or olive oil, full-fat mayonnaise or salad dressing, nuts, avocado, or fatty fish (like salmon). In exchange, subtract a serving or two of sweets or refined bread, pasta, crackers, or cereal.

* If you eat sweets, make it one small serving (or less) of low-fat cake, cookies, or ice cream a day.

* If you're overweight, cut calories. You'll lose excess weight, raise your HDL, and lower your risk of diabetes, heart disease, high blood pressure, and possibly cancer.

* Exercise for at least half an hour on most days. That will raise your HDL, lower your weight, and reduce your risk of diabetes, heart disease, high blood pressure, and possibly cancer.

RELATED ARTICLE: Foods, Not Fats

When's the last time you ordered monounsaturated fats for dinner?

Researchers can debate the pros and con's of monos and polys versus carbs 'til the carrots come home. You need to know what to eat today.

On page 7 are two sample menus that illustrate the debate. They both have 2,000 calories, are low in saturated and trans fat, cholesterol, and sodium, and contain roughly the same amount of vitamins, minerals, fiber, and protein.

The major difference: The High-Unsaturated-Fat Menu has more oil, fattier mayo and salad dressing (unsaturated fats), and less rice or pasta, crackers, and sweets (carbohydrates). It gets 36 percent of its calories from fat.

The Low-Fat Menu is based on the 2,000-calorie DASH Diet (see "DASH--A Diet for All Diseases," October 1997). The DASH diet gets 27 percent of its calories from fat Ours gets 22 percent To get from the Low-Fat to the High-Unsaturated-Fat Menu, we made three trade-offs:

1. We substituted a tablespoon of full-fat mayonnaise (100 calories) for the fat-free mayo in the tuna sandwich. And, to keep calories from climbing, we cut half a cup of rice or pasta (100 calories) from the dinner's saute. That raised the fat from 22 to 27 percent of calories.

2. We replaced the low-cal Italian dressing on the salad with full-fat dressing (135 calories). To compensate, we cut the small serving of frozen yogurt (100 calories) for dessert at dinner. That upped the fat from 27 to 31 percent of calories.

3. We added an extra tablespoon of oil (120 calories) to the saute. In exchange, we cut the crackers (70 calories) from the afternoon snack and another quarter cup of rice or pasta (50 calories) from the saute. That left only half a cup, but it, brought the fat to 36 percent of calories.

In order to keep the saturated fat in the High-Unsaturated-Fat Menu from rising above seven percent of calories, we also had to switch from olive oil (which has two grams of sat fat per tablespoon) to canola oil (which has one).

Some caveats: This is just one day's diet (for variations, see below). If you eat more than 2,000 calories a day, you'll have more foods to add or subtract And the diet is designed by a nutritionist In the real world, many people won't precisely add and subtract calories. And some will forgo vegetables or fruit, rather than dessert, to fit in the extra oil.

Variations on the Low-Fat Menu

What good is one day's diet? Not much, unless you know how to vary it Obviously, you can substitute any fruit, vegetable, or low-fat dairy food for another. Here are some other tips:

* Sandwich. Instead of tuna salad, try chicken or egg (white) salad made with low-fat mayo or sliced turkey with mayo on the bread. Vegetarians could spread hummus on some crusty bread. Or ditch the sandwich,and have a bowl of lentil or split pea soup and a whole wheat roll.

* Saute. Instead of rice or pasta, switch to couscous or flour tortillas (fajitas). Try other vegetables like mushrooms, tomatoes, and green or red peppers. Instead of chicken breast, try rinsed canned beans (black, pinto, white, etc.) or scallops, shrimp, or tofu.

* Traditional dinners. Not used to mixing all your vegetables (and chicken, fish, or me together in one dish? Whip up a small portion of chicken, fish, or lean meat and serve it with lots of side dishes--three or four servings of vegetables and some cooked rice, pasta, or other grains.