he Atkins diet gained a modicum of respectability this month when scientists reported that two clinical trials found the high-fat, high-protein, low-carbohydrate diet did not cause disastrous increases in serum cholesterol and even reduced one or two cardiac risk factors.
The studies, reported in The New England Journal of Medicine, compared the effects on weight loss and cardiovascular risk factors of the Atkins plan with the conventional low-fat, low-calorie diet recommended by most health experts. Both diets resulted in weight loss, but participants on the Atkins diet lost more weight, faster.
But it is too soon to jump on the Atkins bandwagon in hopes of achieving bathing-suit slimness by the Fourth of July. Yes, the diet does help obese people lose weight quickly, and those wanting to shed 10 pounds in the next four weeks could achieve that goal. But the research suggested that by Labor Day many, if not most, are likely to be back to their starting weight.
The first five to seven pounds lost on Atkins are not fat but water, released by the body when it gets little or no starch or sugar from food. So as soon as you are unable to resist that bun with your burger or summer's succulent sweet corn, a cooling ice cream cone, thirst-quenching watermelon or a bag of fries, those lost pounds are likely to come bounding back.
Neither of the new studies was designed to determine either long-term safety or effectiveness of this regimen, which puts foods like bread, pasta, rice, potatoes, carrots, tomatoes, corn, bananas, winter squash, dried beans and peas, cereal and, of course, ice cream, cake, cookies, pies, sweet rolls, doughnuts, candy and bagels on the don't-eat-them list and suggests instead indulging in bacon and eggs, steaks and cheese, cream (but not milk) and butter instead.
The predictions were that this diet would spell disaster for the heart and blood vessels. But the new studies showed for the first time in randomized clinical trials that there may be some cardiovascular benefits to this high-fat weight-loss regimen.
As expected when people lose weight, cholesterol levels did not rise (indeed, they fell in some participants) and, as expected when the diet contains little sugar and refined starches, triglyceride levels fell. Insulin sensitivity also improved again, no surprise when limited carbohydrates are consumed.
Perhaps the only surprise finding among Atkins participants was a rise in the so-called good cholesterol, protective H.D.L.'s, which may indicate that the body compensates for a diet rich in saturated fats and cholesterol by producing more of the substance that helps to keep arteries clear of fatty deposits.
What Is and Isn't Known
As noted in the editorial accompanying the reports, the two studies, which involved obese or severely obese participants, were short-term. (One lasted six months and the other a year.)
About 40 percent of the participants dropped out of the studies and were lost to follow-up. In other weight-reduction studies, dropouts are usually people who fail to lose weight or regain their initial losses. It nearly always means that they did not stay on the assigned diet.
Among those who did stay in the programs, the differences in the amount of weight lost on the two diets were not drastic and, in the one-year study, those following Atkins started gaining weight back after six months, resulting in no significant weight-loss differences between the two diets by the end of the year.
Atkins advocates are fond of blaming the push for low-fat diets for the astronomical rise in obesity among Americans in the last 20 years. They say that as people spurned fats they turned to carbohydrates instead and started gaining weight. But three facts must be noted:
|Americans are not eating less fat; rather, per capita consumption of fat has risen by 10 pounds a year since 1973. All things being equal (which they are not), this alone would result in an average of 11 more pounds than people weighed 30 years ago.
|Americans are also eating more carbohydrates, but not the whole grains, fruits and vegetables that weight-control experts and health promoters recommend. They are eating far more sugars (20 pounds more per capita since 1975, another 10 pounds of body weight) and more refined starches as they overindulge in fat-free or low-fat cakes, crackers and so on.
|Americans are eating more calories, which is the real cause of weight gain. That is why the percentage of calories from fat has fallen while total fat intake has not.
These dietary changes have been accompanied by an overall decline in physical activity. In other words, we are consuming more calories and burning fewer. That is why we have an obesity epidemic.
A final and critically important unknown remains the long-term safety of a diet rich in saturated fats and relatively limited in the whole grains, fruits and vegetables that countless studies have linked to reduced rates of heart disease, stroke and cancer, the nation's leading killers.
No Diet Fits All
It is perhaps worth noting that the precipitous gain in the numbers of obese and overweight people has occurred during the 30 years since Dr. Robert Atkins, who died on April 17, first published his "diet revolution." Since the diet's resurgence in recent years, there has been no notable turnaround.
Recent studies have strongly suggested that carbohydrate-rich, low-fat diets with only modest amounts of protein may be less effective in achieving and maintaining weight loss. Fat and protein are digested more slowly than carbohydrates and may delay the return of hunger.
Also, while it may be easy to overeat or binge on cake or cookies, few people can consume large quantities of steak, burgers without buns and unsweetened whipped cream.
That is why, as the new studies show, Atkins adherents eat fewer calories than they did before starting the diet, and it is this calorie reduction that accounts for their weight loss.
If you want to try a diet that many experts concerned about both weight and health now recommend, it should contain about 25 percent of calories from fats primarily from vegetable sources like olive, canola and nut oils, avocados, beans, nut butters, nuts and seeds, along with fish and lean red meats and poultry adding up to about 20 to 25 percent of calories from protein.
Rounding out this diet are whole grains and ample amounts of vegetables and fruits. On this less restrictive diet, the weight loss may be slower than with Atkins, but it is more likely to stick.