Michael Fumento

The title invokes images of thin beautiful people, but it’s just a variation on a concept that predates bikinis by almost a century.

Yet, "There is no compelling evidence that in normal individuals day-to-day fluctuations of the blood glucose level are an important determinant of how much food is consumed," University of Washington endocrinologist Michael Schwartz told me. But "Although the concept that insulin triggers weight gain has little scientific merit," he wrote earlier in the journal Science, "it remains a key selling point for advocates of diets that are low in carbohydrate and high in protein and fat."

Advocates like Atkins and Agatston.

And because the South Beach diet is indeed low-carb, Agatston feels compelled to claim that, "When we eat fats, we become satiated." False. The literature on this is both voluminous and clear. Fat and carbohydrates reduce hunger equally, although protein may have a slight edge.

Were either the hyperinsulinemia or fat-satiety theories true, it would certainly show up in the decades of studies comparing diets of varying fat and carbohydrate content. It does not. For example, in April 2001 the Journal of the American Dietetic Association reviewed "all (such) studies identified," over 200 total. Conclusion: "Weight loss is independent of diet composition."

Most recently, a review in the April 9, 2003, Journal of the American Medical Association found "insufficient evidence to conclude that lower-carbohydrate content is independently associated with greater weight loss compared with higher-carbohydrate content."

In fairness, the South Beach diet is superior to Atkins in two ways. First, it encourages the consumption of healthier unsaturated fats, while saturated fats like lard and those in bacon are emblematic of Atkins.

Second, while the _South Beach diet allows carbohydrates, it promotes higher-fiber ones. Fiber is good for overall health. Further, by adding non-caloric bulk to food, it can [aid weight control](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&listuids=12146567&dopt=Abstract). But South Beach still can’t be called a high-fiber diet since it discourages carbohydrate consumption.

Ultimately neither regimen favors permanent weight-loss, which is why both authors fall back on anecdotes without having published a single study supporting their diets.

Obesity experts who do publish such studies, including those directly comparing Atkins dieters to high-carb dieters, say Atkins works only because it excludes so much of what we normally consume that we end up eating fewer calories. But soon people get bored and repack the pounds. A 12-month study in the May 22, 2003, New England Journal of Medicine showed as much.

Both Atkins and South Beach induce rapid weight loss in the first couple of weeks, because all low-carb diets promote quick water loss. Water is heavy, but it is not fat.

If you do lose fat with South Beach it’s because you’re following the recipes (comprising two-thirds of the book), which amount to a low-calorie diet. But the spontaneously eating Omnivorous Americanus will not stick to recipes for very long.

That’s why, although the subtitle of Agatston’s book modestly calls it "foolproof," a whole chapter is devoted to why people fail on it.

The South Beach Diet does have one other advantage over Atkins, at least in terms of salability. Strangely, it’s become more chic to talk about losing weight than to actually do so; hence a glamorous title draws readers. "South Beach" is chic; "Atkins" is not. (Agatston’s hospital, incidentally, is in the drabber Miami Beach.)

Alas, "chic" is not a scientifically proved method of weight loss and maintenance, while magic is the stuff of fairy tales. Only proper eating and exercise will cause permanent weight loss, as I and countless other former fatties can attest. Seven years later, when I look at myself in the mirror it still seems, well, magical.