Nutrition Action Healthletter
July/August 1996

Carbo-Phobia

Zoning Out on the New Diet Books


BY BONNIE LIEBMAN

"Having just completed Barry Sears's The Zone, I'm hesitant to continue the high-carbohydrate, low-fat approach to nutrition that I've been following for the past several years," writes Nutrition Action reader George H. Bailey. "Is the book cover right when it says: 'Eating carbohydrates could be dangerous to your health'?"

"I lost weight, gained new admiration for protein, kept my respect for complex carbohydrates, and began to question some of the very tenets of dietary dogma," writes reporter Suzanne Hamlin in the New York Times.

Sigh. Another diet craze. And this one's big.

Barry Sears's The Zone has reportedly sold 400,000 copies. And wannabes like Michael and Mary Dan Eades's Protein Power and Rachael and Richard Heller's Healthy for Life are also racking up impressive sales. All say that cutting back on carbohydrates like pasta and bread will solve our battle with the bathroom scale.

Is this the answer we've been waiting for?

Hardly. Sears's advice will probably help you lose weight...but only because you'll be eating fewer calories, not because his untested theories about protein, carbohydrates, and insulin will put you into what he calls "The Zone."

And to experts who have seen miracle diets come and go like hemlines, hair-dos, and celebrity romances, that's nothing new.

"It's one crazy diet after another," says Kelly Brownell, an obesity expert in the psychology department at Yale University. "Over the years we've had the Rotation Diet, the Beverly Hills Diet, the Scarsdale Diet, the Dr. Atkins Diet, the Dr. Stillman's Diet, and on and on.

"They all have a brief flurry in the market. They're all condemned by health professionals either because they're dangerous or because there's no data to support them. And then another comes along, and people say 'Oh, maybe this is the real one.'

"When I get calls about the latest diet fad, I imagine a trick birthday cake candle that keeps lighting up and we have to keep blowing it out."

Science Fiction

Like most of their brethren, The Zone and other "carbo-phobia" diets are based on an eensy-weensy kernel of truth...blown way out of proportion by theory, not evidence.

"It's science fiction," says Alice Lichtenstein, a researcher at the Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University in Boston. "Sears relies on studies that have never been published, peer-reviewed, or adequately controlled. He relies on anecdotes."

Here's a rundown of some of the major claims in the book...and their flaws.

THE BEST DIET
Low-fat? Low-carb? Low-cal? What's the best diet to lose --or to avoid regaining--those extra pounds?

For most people, the battle of the bulge lasts a lifetime. So a weight-loss regimen also has to minimize the risk of heart disease, cancer, and other illnesses. Almost all experts agree that, to stay healthy, everyone aged two or older should eat a diet that is:

  • Low in saturated and trans fat. That means cutting way back on red meat, most cheeses, whole or 2% milk, and most pastries and fried foods.
  • Rich in fruits, vegetables, beans, and whole grains like whole wheat breads, crackers, and cereals.
The only real debate is how much oil or nuts or other foods rich in unsaturated fat versus how much carbohydrate (mostly in the form of more breads, cereals, and pasta) should round out the diet. The answer isn't clear.

"The research we have is equivocal," says G. Ken Goodrick, a researcher at the Baylor College of Medicine in Houston. "You can cut back on all kinds of calories or just fat calories--the results are the same."

But a diet that's low in all fats--saturated, unsaturated, and trans--has several advantages. For one thing, it's simpler to cut all fats than to cut just saturated and trans fats, especially when trans fats aren't listed on labels.

What's more, "if you didn't limit fats, it would be hard to get all the vitamins and minerals you need and still hit the 1,500 to 1,600 calories that dieters and many women eat daily," says Susan Foerster, a dietitian who helped design the California Daily Food Guide for the California State Department of Health Services.

And, at least in short-term studies, a low-fat diet also seems to promote weight loss by helping people feel full. (The loss may diminish over time, but there aren't many good long-term studies.)

"When we put people on a very-low-fat diet, they felt so full that they ate fewer calories and lost weight," says researcher Alice Lichtenstein. Her low-fat diet, though, was loaded with fruits, vegetables, and whole grains.

"If we had offered them fat-free chocolate cake or fat-free ice cream, we might not have seen a decrease in calorie intake," Lichtenstein adds. "A fat-free cake doesn't produce the same sense of fullness as four apples."

While fat-free cakes and ice cream are healthier than fattier ones, "they send out the wrong message: that calories don't count--only fat does," she says.

And don't forget exercise. Studies suggest that if anything helps to keep unwanted pounds from returning, it's exercise. Says Goodrick: "Your chances of long-term weight maintenance are pretty slim if you don't get into a regular exercise program."

Claim #1: Americans are fatter because we're eating less fat. Like other anti-carbohydrate books, The Zone blames our epidemic of obesity on advice from health experts to eat less fat and more carbohydrates like pasta and bread.

"All data analysis during the last fifteen years," Sears writes, "shows that despite the fact that the American public has dramatically cut back on the amount of fat consumed, the country has experienced an epidemic rise in obesity."

Did he say "data"? According to the latest data from the National Center for Health Statistics, fat intake has barely budged. The average American ate 81.4 grams of fat a day in the late 1970s and 82 grams a day in the late 1980s.

If a low-fat diet isn't causing our national waistline to bulge, what is? Sears blames it on the extra carbs we're eating. But there's a simpler explanation: we're eating 100 to 300 more calories--and may be exercising less--than we were in the late '70s.

That's not a lower-fat diet, it's a higher-calorie diet.

Claim #2: Carbohydrates cause obesity. Too little exercise? Too much food? Too much fat? None deserve the biggest blame for our bulging body parts, says Sears. Carbohydrates are "the reason you're fat."

Why? Because "when we eat too much carbohydrate, we're essentially sending a hormonal message, via insulin, to the body....The message: Store fat."

"I disagree strongly with the notion that having high blood insulin, by itself, makes you gain more weight," says Gerald Reaven, an endocrinologist at Stanford University whose work is cited by Sears.

When it comes to gaining--or losing--weight, what matters isn't insulin, but calories.

"There are so many studies showing that if you decrease calories, people lose weight, and it doesn't matter if you do it by cutting fat, protein, or carbohydrate," says Reaven. "A calorie is a calorie is a calorie."

Sears is right when he says that--for some people--a very-high-carbohydrate, very-low-fat diet can raise insulin levels...and that high insulin levels raise the risk of heart disease. But there's simply no good evidence that high insulin levels make you fat.

Claim #3: Calories don't count...protein does. People who follow The Zone diet to lose weight don't count calories, they count protein. Why? "The closer you get to the center of that ideal protein-to-carbohydrate ratio (0.75), the better your ability to control your balance of eicosanoids," says Sears.

Eicosanoids (eye-KOH-suh-noids) are hormones that help regulate inflammation, the blood's tendency to clot, and the immune system. They may indeed play a role in heart disease, stroke, and other diseases.

But Sears takes it too far. "Virtually every disease state--whether it be heart disease, cancer, or autoimmune diseases like arthritis and multiple sclerosis--can be viewed at the molecular level as the body making more bad eicosanoids and fewer good ones," he says.

And what causes your body to make "bad" eicosanoids? You guessed it. Too much insulin caused by eating too much carbohydrate, says Sears.

"I am unaware of any evidence that changes in insulin have an effect on eicosanoids, and that eicosanoids cause everything from cancer to PMS," says Reaven.

Nor is there evidence that eating equal amounts of protein and carbohydrate at every meal, as Sears suggests, lowers insulin levels. "Protein--when eaten alone--increases insulin secretion," says Reaven. "I see no reason in the world why it would be any different if the protein were eaten with carbohydrate."

But, he adds, "no one has ever studied it." In response to the publicity generated by The Zone, he's hoping to.

What's the Harm?

Okay, so Sears and his fellow carbohydrate-bashers have few or no published studies to back up their claims. Why do some Zone readers say that they're losing weight and feeling great?

Because The Zone diet cuts calories. "Although Sears hides it, the book advocates a low-calorie diet," says Lichtenstein. "If you follow his advice, it adds up to about 1,700 calories a day." How could you not cut calories when you eliminate most of the bread, pasta, cereals, and grains you typically eat?

The question is: Will people stick to it?

"Given what we know about adherence to a low-calorie diet, the answer is no," says Lichtenstein.

Reaven agrees. "It's the same thing that happens with all these diet crazes. People who are desperate do what the books say for a couple of months. They lose weight, so they feel terrific. Then they get tired of eating egg whites or whatever, and they go on to the next diet."

And what if you could stick to a low-carbohydrate diet for the rest of your life? Would it be harmful?

For the people who take Sears's word that The Zone diet can fight diseases like AIDS and cancer, it could be. "He's preying on vulnerable people who can't look out for themselves," says Lichtenstein.

As for healthy people, Sears's diet isn't as bad as some others. In Protein Power, for example, the Eadeses say that it's fine to eat steak, pork ribs, and other fatty meats as long as you don't load up on starch and sugar at the same time. All that saturated fat is a recipe for clogged arteries. Ditto for the Hellers' Healthy for Life.

Sears recommends low-fat protein foods, which should keep a lid on saturated fat. But "sometimes people don't get the subtleties," says Lichtenstein. "When they hear 'more protein,' they may go out to a ribs place or eat a few Big Macs without the buns."

And Sears still limits most grains and a number of vegetables (like carrots and sweet potatoes) and fruits (like bananas and orange juice). He claims that a vegetarian diet is as far as you can get from The Zone...one step farther than if you ate nothing but Snickers bars, to be precise.

"Populations that eat vegetarian diets have lower rates of heart disease, cancer, and stroke," counters Frank Sacks of Harvard Medical School, who has studied vegetarian diets for 20 years. They also tend to be leaner, not fatter, than other groups.

Sacks's conclusion is based on dozens of studies. Sears hasn't published a single diet study.

And that ought to change, says Yale's Kelly Brownell: "When these diets come down the road, neither the public nor the government makes the authors prove that they work. That's a horrible shame."


THIN FOR LIFE

"People who have met me within the last 25 years find it hard to believe that I was once a third bigger than I am now," says Jane Brody, personal health columnist for the New York Times, in the forward to Thin for Life (1994, Chapters Publishing, Shelburne, Vermont).

"I tried dieting. All kinds of diets....And sure, I would lose weight, but then I'd gain it back--and usually some extra pounds to boot--when I got sick and tired of feeling deprived and living on eggs and grapefruit or whatever happened to be the popular weight-loss concoction of the day.

"As my girth expanded, I got increasingly desperate and tried starving all day and eating only one meal at night....But as soon as I put the first morsel of food in my mouth, I couldn't stop eating....I had turned myself into a compulsive eater who knew the locations of every all-night grocery in town.

"Then one day I panicked. I decided that if I was going to be fat, so be it, but at least I could be healthy and fat.

"I gave up diets and gimmicks and cycles of starving and binging, and started eating: three wholesome meals, with wholesome snacks if I was hungry between meals, and one little 'no-no' each day--two cookies, a couple of spoons of ice cream, a thin sliver of cake or pie.

"And I put myself on a regular exercise program. Every day I would do something physically challenging: walking, cycling, skating, swimming, tennis....Losing weight wasn't part of this plan, but lose weight I did."

Twenty-five years later, Brody is still 35 pounds lighter than when she gave up dieting. She is what Anne Fletcher would call a "master at weight control."

Almost any diet book can help you lose weight. The trick is to keep it off. That's what sets Thin for Life apart. Fletcher interviewed 160 ordinary people who have lost at least 20 pounds--and kept it off...for at least three years.

Some of their strategies: Nip weight-gain in the bud, from day to day, or meal to meal; think about what you can eat, not about what you can't; don't deny yourself your favorite food; and don't worry if you slip up now and then.

The book shows you how to avoid "high-risk situations" that can make you lose your resolve, how to "put a lid on emotional eating," how to "do away with anti-exercise excuses," and how to "tell when you need outside help."

"Anne's program is not a prescription, it's an approach that can be molded to individual lifestyles and temperaments," says Brody.


Nutrition Action Healthletter