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Original Research: Low-carb versus Low-fat diets

Another bit of original research has recently been published in the Annals of Internal Medicine comparing a low carbohydrate diet and a low fat diet.  It evaluated the effects on weight loss and other cardiovascular markers in patients who are at risk for cardiovascular disease but had no known disease yet.

Nutritional studies are often very difficult to do because when you intervene in someone’s diet it is impossible to only change one thing.  A lower carbohydrate diet by necessity is going to be higher in either fat or protein (or both) than before.

Here’s a summary the editors published about the article.  I’ve italicized some key aspects to the study.

What is the problem and what is known about it so far?

Obesity is a common problem that increases the risk for cardiovascular disease. Diets may emphasize reducing one’s intake of fat or carbohydrate. It is unclear whether one approach is better than the other, and they have not been compared in studies that included a substantial number of black people.

Why did the researchers do this particular study?

 

To compare weight loss from low-carbohydrate and low-fat diets.

How was the study done?

 

The researchers enrolled obese people who did not report a history of cardiovascular disease and randomly assigned them to a low-fat or low-carbohydrate diet. During the 1-year study, participants also attended individual and group dietary counseling sessions. Data on participants’ weight, waist size, blood test results, and physical activity were collected at regular intervals during the study. About half of the participants were black.

What did the researchers find?

 

At 3, 6, and 12 months, participants on the low-carbohydrate diet had lost more weight than those on the low-fat diet. At 12 months, those in the low-carbohydrate group had lost an average of 7.7 pounds more than those in the low-fat group. Although participants in the low-fat group had a greater reduction in their waist size at 3 and 6 months, there was no difference at 12 months. Overall, blood levels of certain fats that are predictors of risk for cardiovascular disease also decreased more in the low-carbohydrate group. Physical activity was similar in the groups throughout the study, suggesting that the greater weight loss among participants in the low-carbohydrate group was not because they exercised more. When the researchers evaluated the black and white participants separately, the results were similar.

What were the limitations of the study?

 

The study lasted 12 months, and whether the participants will maintain the weight loss is not known (people often lose weight initially on a diet but gain it back later). In addition, because the study lasted only 12 months, it is not known whether the reductions in blood markers of risk for cardiovascular disease will be accompanied by reductions in the development of coronary artery disease, heart attacks, strokes, and other cardiovascular problems. Finally, this study involved regular meetings with dietary counselors, and whether results would be similar for people on a similar diet without such counseling is uncertain.

What are the implications of the study?

 

A low-carbohydrate diet may be an option for people seeking to lose weight or reduce risk factors for cardiovascular disease.

 

The low carbohydrate diet produced a more pronounced weight loss over 12 months which couldn’t be attributed to a difference in exercise levels.  Also one of the successes of this study was the use of dietary counselors to help the participants follow the dietary recommendations of their group.  We have found that to be a key element to success too.  For the last five years we have developed a thriving program of nutritional counseling with nurse practitioners and physician’s assistants that has resulted in several thousands of pounds of documented weight loss, a normalization of most of our participants’ biochemical cardiovascular risk markers, a reduction in medication burden, and a reversal of the disease state in many.

We encourage all our patients who desire to lower their risk for heart disease or improve their weight to a healthy level come meet with our nutritional counselors.  Their visits are billable to all insurance programs and typically patients only have  copay as their out of pocket expense.

I encourage you to call the office at 539-0270 to set up an appointment today.

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