Low-Carbohydrate Diets and Heart Disease

There has been longstanding controversy over low-carbohydrate diets. Those who write books about such diets make dramatic claims about weight loss as well as the overall health benefits from eating an extremely low-carb diet. Unfortunately, there has not been proof that eating this way prevents disease or helps with weight loss.

These diets have been around for a long time and were popularized by Dr. Robert Atkins in the early 1970s. Dr. Atkins has admitted to making the diet up without any real foundation, claiming that he thought it just made sense. Since that time millions have used Atkins-style diets such as South Beach Diet and The Zone Diet. Only recently has there been any substantial research about whether following such plans actually help.

In a recent study Thomas Halton and his colleagues looked at 82,000 women who participated in the Nurses' Health Study. (NEJM 2006;355:1991-2002). The nurses had kept detailed records of their diets over a period of about 20 years. The researchers created a scoring system for diets that were lower in carbohydrates and higher in proteins and fats. The higher the score (on a scale of 1 to 30) the more closely the nurses were felt to have adhered to a low-carbohydrate diet plan.

The purpose of the study was to determine whether those eating a low-carb diet were at higher risk for developing heart disease. This is because most such plans replace carbohydrates with animal protein that is high in saturated fat. The typical thing patients will say to me is that they had 3 eggs and 4 slices of bacon for breakfast but no toast or cereal. Such a diet high in saturated fat is of concern for developing heart disease.

When the researchers compared those with the lowest Low-carbohydrate Diet scores to those with higher ones they found no difference in the risk of heart disease. There were a number of interesting findings when Dr. Halton and his colleagues looked carefully at the data. Those women eating higher amounts of vegetable protein and vegetable fat had a much lower risk of heart disease.

There was no difference in the groups otherwise. Those eating more animal protein and lower carbs had about the same risk as those eating a higher carbohydrate diet. The reason for this might be that the women eating higher carbohydrates were eating those with much more simple sugars (a higher Glycemic Index). The benefit from eating less fat and protein may be offset by this.

The most interesting finding to me is that the women eating a more strict low-carbohydrate diet weighed more. Their Body Mass Index was higher in all categories. Since the Atkins diet was designed for weight loss it certainly appears to fail on this account.

What this means for you

A diet that uses carbohydrates that are more complex along with lower animal fat and animal protein is good for you. This is the foundation of the research on Mediterranean style diets. This has been shown to prevent heart disease and control weight, plus the food is great.

First posted: November 14, 2006