New Doctor, New Diet, but Still No Cookies

Dr. Agatston — whose office is not in South Beach, by the way, but the older, tamer neighborhood to its north — is not far from that giant of diet doctors, the late Dr. Robert Atkins, in his belief that refined sugar and white flour are the villains behind the nation's climbing obesity rate. Like the Atkins diet, the South Beach diet strictly limits bread, potatoes and other carbohydrates, especially during a two-week initiation period, and allows the dieter to eat red meat, eggs and cheese.

But while the Atkins diet allows just about any fatty food that is not also starchy, Dr. Agatston advocates mostly unsaturated fats, like those in olive oil, nuts and oily fish like salmon. Butter is nowhere in the South Beach diet meal plans, nor is bacon or anything fried. The South Beach diet also differs from Atkins in that it allows carbohydrates — though only those high in fiber, like multigrain bread and wild rice.

Dr. Agatston's premise is that most carbohydrate-rich foods are so processed that they immediately turn to sugar in the body. That, Dr. Agatston says, forces a quick spike in blood sugar and nearly as quick a decline. The spikes lead to more hunger, he says, and — this is the part that many experts dispute — to inevitable weight gain.

"Nobody in the history of man ever ate complex carbohydrates like we have," Dr. Agatston said last week during an interview squeezed between a photo shoot and a meeting about his new heart-imaging center, set to open in December.

The diet revolves around the glycemic index — the amount that a carbohydrate increases sugar in the blood compared with the amount that the same quantity of white bread raises it. The concept of the index as crucial to weight gain or loss has been around since the early 1980's, when it was used to help people with diabetes choose proper diets. But skeptics — including the American Diabetes Association, which has not endorsed the index — say a food's glycemic index fluctuates depending on how much is eaten and what other foods are eaten.

Foods with a low glycemic index, like lentils, soy milk and low-fat, artificially sweetened yogurt, do not raise blood sugar as quickly and sharply as high-numbered items like gnocchi, baked potatoes and pretzels.

High-glycemic-index foods cause the body to release a lot of insulin, which quickly lowers the blood sugar again and causes hunger to recur, the theory goes. Those with low indexes break down into sugar more slowly, for longer-term energy.

Carrots are shunned, for example, because the body absorbs their sugars rapidly. But Dr. Marion Nestle, chairwoman of the department of nutrition and food studies at New York University, said it would take over a pound of carrots to spike the blood sugar as high as the index warns.

"What it comes down to is that this is a standard 1,200- to 1,400-calorie-a-day diet, so of course people are going to lose weight," Dr. Nestle said. "I do think there's something to the glycemic index, but I just don't think it's the be-all and end-all, and that it's the root of obesity."

Dr. Nestle and other experts said they preferred South Beach to Atkins because it promotes only healthy foods. Several studies suggested the high-fat Atkins diet was safe for the heart in the short term, though Dr. Gary Foster, an author of one study, said the South Beach diet seemed "more informed."

"If this approach says: `Guess what. We think saturated fat is a bad idea,' it will get a greater mass acceptance," said Dr. Foster of the weight and eating disorders program at the University of Pennsylvania.

"If you compare the two menu to menu there is very little difference" between the strict first phases of the Atkins and South Beach diets, said Colette Heimowitz, director of education and research for Atkins Nutritionals. "It's a myth that Atkins is all about meat and discourages healthy fats."

The first two weeks of the South Beach diet are the most difficult, according to testimonials in Dr. Agatston's book, because they allow only foods with the lowest glycemic indexes. Fruits, juices, alcohol, caffeinated coffee and most dairy foods are forbidden. Dessert is part-skim ricotta cheese mixed with cocoa powder or almond extract. The closest thing to starch is "Surprise South Beach Mashed `Potatoes,' " otherwise known as puréed cauliflower.

The goal is to stabilize the blood sugar, and with it, the appetite. The book promises weight loss of up to 13 pounds in the first two weeks, which some dietitians see as a red flag.

Yet Ms. Jackson said she liked Phases 2 and 3. In those, fiber-rich carbohydrates and unsaturated fats are gradually reintroduced. Participants are supposed to stay in Phase 2 until they reach their desired weights, then move on to Phase 3 indefinitely. But it's back to Phase 1 if they regain pounds, a step Ms. Jackson warned verged on the unhealthy.

"If you don't read it for Phase 1 and just look at the healthy menu plans in Phases 2 and 3, it's a good book for that," she said. "It's definitely healthier than Atkins, but at the end of the day, if you are losing weight on this diet it's because you're eating fewer calories than you did before."

Dr. Agatston agrees, but says people consume fewer calories because his diet has banished their cravings by stabilizing blood chemistry.

"The measure of whether the diet is working is, Are you getting cravings in the late afternoon and in the evenings?" he said. "People who do really well lose 40 pounds and perhaps gain back 5 to 10, but their blood chemistries continue to do well and they don't get the cravings."
The Atkins diet puts people into ketosis, a condition in which the body converts stores of fat into energy because it has been deprived of sufficient carbohydrates. While ketosis is not dangerous for healthy people, Dr. Agatston said, he did not want his diet to induce it because the patients he designed it for had hypertension.

Dr. Bonnie Brehm, an assistant professor at the University of Cincinnati who has studied low-carbohydrate diets, said both Atkins and South Beach dieters should be monitored long term for the effects on kidney function, since high-protein diets make the kidneys work harder. High protein intake can also strip the body of calcium, Dr. Brehm said.

But Ms. Jackson, the Chicago dietitian, said Dr. McGraw's focus on changing attitudes toward food and toward exercising more made good sense.

"The idea of `Don't look to a diet book to fix everything but make small changes to what you're already doing' is one I'd like to see more of," she said.