Low-carb diets get some vindication

[Guest guest]

[The question is... when will these studies and articles start mentioning

the role of insulin? While the absolute number of calories is important,

the body's metabolic response to the three macronutrients is the

determining factor in blood lipid profiles and other markers of health or

illness. -- David]

 

Low-carb diets get some vindication

Two new studies show faster weight loss over the short term

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By Rosie Mestel

Los Angeles Times

Originally published June 20, 2004

 

Obesity rates are rising, but science has barely weighed in on the best way

for people to shed fat. That state of affairs is starting to change, and

doctors are getting a surprise or two.

 

Last month, the popular carb-slashing Atkins diet received a dollop of

endorsement from two studies after years of being pooh-poohed by health

specialists. The studies, published in the journal Annals of Internal

Medicine, showed that the meat- and fat-rich regimen caused faster weight

loss in the short term than a conventional low-fat diet.

 

More important - because many had feared that the diet, even if slimming,

might unfavorably affect cholesterol levels and be bad for the heart - the

low-carb regimen also seemed to improve the dieters' blood fat profiles.

 

But Atkins, like every other diet, is no miraculous fat-melter. The longer

of the two studies suggested that a low-carb regimen might be harder to

maintain beyond six months compared with a low-fat approach: By the end of

the year, the low-fat dieters had caught up and lost the same - very modest

- amount of heft.

 

In addition, even though on average people on low-carb diets didn't

experience rises in their so-called " bad " (or LDL) cholesterol levels,

about 30 percent of individuals did.

 

Even with these caveats, " We can no longer dismiss very-low-carbohydrate

diets, " said Dr. Walter Willett, a nutritional epidemiologist at the

Harvard School of Public Health, in a written editorial accompanying the

papers. To maximize the diets' healthfulness, he added, people should avoid

going hog-wild on fatty bacon and red meat - opting instead to eat healthy

oils (monounsaturated and polyunsaturated fats) and get protein from fish,

beans, nuts and chicken.

 

The weight-loss regimen popularized by the late Dr. Robert Atkins - rich in

meat, eggs and cheese but almost bereft of grains, potatoes and fruit - is

highly popular but had not been tested in a scientifically rigorous way

until last year, when two studies reported that very obese and moderately

obese people lost more weight initially on the Atkins diet than on a

conventional diet.

 

The studies published last month bolster and extend these findings.

 

Conducted at the Philadelphia Veterans Affairs Medical Center, the first

study enrolled 132 severely obese adults who had an average weight of 288

pounds. Many of the patients in the study had diabetes or other risk

factors for coronary artery disease.

 

Roughly half of them were instructed to pursue a low-fat diet in which they

were to eat 500 fewer calories a day. The others followed a regimen in

which they were to limit their carbohydrate intake to less than 30 grams

daily but were not instructed to count calories or fat. Both groups were

counseled on the diets each week.

 

The scientists reported last year that at six months, the low-carbohydrate

group had lost an average of about 13 pounds, compared with 4 pounds for

the low-fat group.

 

Last month, the scientists reported that after one year, individuals on the

Atkins-style diet largely kept the weight off but did not continue to lose

more weight. The low-fat group continued to lose weight slowly over the

course of the year.

 

Total weight loss for both groups over the year was slight: an average of

11 to 19 pounds for the low-carb group and seven to 19 pounds for the

low-fat group.

 

In addition, the study found that diabetic patients improved control over

their blood sugar levels using the low-carb approach.

 

The second investigation was funded by the Robert C. Atkins Foundation,

although the foundation did not take part in the study or its analysis.

Conducted at Duke University Medical Center in Durham, N.C., it enrolled

120 moderately obese adults who had high blood cholesterol levels.

 

At six months, participants who followed a low-carb approach had lost an

average of 26 pounds, compared with 14 pounds for the low-fat group.

 

Weight loss wasn't the only effect of these diets. Both studies found that

levels of triglycerides - blood fats that are risk factors for heart

disease - fell further in the low-carb group than in the low-fat group.

Levels of HDL, or " good " cholesterol, also appeared to improve more in the

low-carb group.

 

Still, experts said more studies were needed to ensure that the HDL lipid

change was favorable and that the higher amounts of fat consumed on an

Atkins-style diet would not increase a dieter's risk for heart disease.

 

The American Heart Association issued a statement expressing concern about

the safety of the diet, given its richness in saturated fats - and noting

that at one year, in any case, the results for the diets were a wash.

 

To be safe, people on an Atkins-style diet should have their blood lipids

monitored regularly in case their " bad " cholesterol goes up, said Dr.

William Yancy, assistant professor of medicine at Duke and lead author of

the study there.

 

If a low-carb diet sheds more fat in the short term - why does it? Atkins

always held that the secret of his diet was ketosis, a body state in which

fat would be burned more efficiently. But the key may be rather less

magical, said Dr. Frederick Samaha, chief of cardiology at the Philadelphia

Veterans Affairs Medical Center and co-author of the Philadelphia study.

 

Low-carbohydrate diets are richer in protein and fat, which have the effect

of making a person feel full more rapidly. That means they'll eat fewer

calories.

 

Not only that, but people following an Atkins-style diet have many more

food restrictions, which could also slash the number of calories they consume.

 

These very restrictions could make it harder to stay with the diet over the

longer haul - and might easily be the reason why patients on low-carb diets

eventually stopped losing weight, while low-fat dieters continued to lose,

Samaha said.

 

" I think it's partly the monotony - but also, the low-carb diet really

forces people to prepare their own foods - to go out and buy fish and

chicken and meat, " he said. " Whereas for low-fat diets there's a lot of

really good, readily available food to grab off the shelf. "

 

The Los Angeles Times is a Tribune Publishing newspaper.