Medical studies lend weight to low-carb-diet claims

By Troy Goodman
The Salt Lake Tribune
11/19/2002

Eat the sausage, forget the bun. And tropical oils and butter? Maybe not so bad after all.

Early medical studies on fat-reduction theories fed to Americans through so-called fad diet books show that some do work: The low-carbohydrate Atkins diet, for one, helps people lose weight, and eating more of certain kinds of fats can help melt calories away, researchers say.

Other diet schemes appear not to work so well, including high-carb/low-fat or the high-protein, low-fat plans, because they fail to reduce unhealthy cholesterol levels and other factors in the body.

The results have yet to be published but were presented recently by scientists from Duke University in North Carolina, the University of Colorado in Denver and McGill University in Montreal. All were attending the American Heart Association 2002 annual scientific session in Chicago.

The diet studies mirror ongoing research trials worldwide looking at fundamental changes in eating habits to combat epidemic obesity and heart disease.

"Science is an evolutionary process," said Robert Bonow, a cardiologist at Northwestern University in Chicago, who praised the range of studies looking at diet and obesity risks.

He said more extensive research is needed to analyze trends in dieting and what happens when you mix in more-established advice on consuming more fruits and vegetables to shed weight, lower blood fats and fight cardiovascular disease.

"All of these evaluations are important ... but right now we don't have a good solid base" to recommend any one diet over another, said Bonow, who also serves as the outgoing president of the heart association.

The group used their recent presentation to update guidelines on fish consumption, urging people with documented heart disease to eat one serving each day of oily fish, such as salmon, trout or albacore tuna, to lower their risk of heart attacks and strokes.

Of course, many doctors and health experts say reduced calorie intake and increased physical activity is the best way to keep your heart and waistline in good form.

But what about the millions who swear by the high-fat, low-carb method outlined in the best-selling books by Robert Atkins?

Duke University's Eric Westman said he decided to test the practice of limiting carbohydrates and loading up on taboo fatty foods to see how it affects cardiovascular health.

After six months, the 120 obese volunteers monitored by Westman and his research team found Atkins dieters lost 13.8 percent of their girth, compared with 8.8 percent of the weight loss experienced by study subjects following a traditional low-fat diet (eating foods with less than 30 percent of their calories from fat).

The blood-cholesterol rates dropped a little in both groups; there was a higher amount of good cholesterol, called HDL, found in the veins of Atkins subjects compared with the low-fat dieters. High LDL and low triglyceride levels can protect normal- and high-fat people from advanced heart disease.

The study was partly funded by the New York-based foundation that Atkins runs.

A study by Robert Eckel, from the University of Colorado in Denver, found that a high-carb, low-fat diet helped people lose weight only if their bodies were engineered to burn the carbs rather than store them as fat. Consequently, obese people who had the inherited propensity for fat storage were not helped by the high-carb diet — even though thinner folks in the study sometimes ate a high amount of carbs and kept off extra pounds without increasing their physical activity.

"To help from gaining weight you need to eat what you can burn," Eckel said.

Another study found that a high-protein diet did little to help people with a cardiovascular condition called hyperinsulinemia, which is a risk factor for obesity and diabetes. Women in the study, however, appeared to earn some benefits from regular high-protein menus, retaining more lean muscle mass compared with total body fat.

Data from McGill University in Montreal also found certain fats seem to earn men greater weight loss compared with another group who ate a diet containing plenty of olive oil.

The researchers said "medium chain triglycerides," found in coconut oil, palm kernel oil and butter, "in combination with plant sterols and flaxseed oil may help prevent cardiovascular disease by controlling lipid levels while also increasing energy expenditure."

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