Weight Loss Study Compares Low Carbohydrate/High Protein Diets
A widely reported Israeli study, published in the New England Journal of Medicine, compared three popular weight loss diets - low fat, which was attributed to the American Heart Association, low carbohydrate/high protein based on the Atkins diet, and Mediterranean style. The researchers found that people on the low carbohydrate/high protein diet lost slightly more weight over a two year period. Does that mean that people who are trying to lose weight should adopt a low carbohydrate/high protein diet?
An important point to clarify is that the Israeli researchers began their study in 2005, before the association’s dietary recommendations were revised in 2006. Therefore, the diet identified as being low-fat and based on American Heart Association guidelines is no longer recommended by the association, which does not currently advocate restricting total fat intake to less than 30 percent for weight loss.
In the American Heart Association’s 2006 dietary recommendations, the association stresses the importance of limiting “bad fats,” and says that saturated fats should be less than seven percent of calories consumed daily, and trans-fats should be less than one percent. A range between 25 – 35 percent for total fat consumption is suggested for most people, not just those trying to lose weight. Saturated fats are typically found in meat products and in tropical oils, such as coconut and palm oil. Trans-fat is man-made, and is also known as partially-hydrogenated fat – it is found mainly in commercially baked goods.
Just as importantly, the 2006 recommendations focus on what people should eat more of -- fruits, vegetables, low-fat dairy products, lean-meats, poultry and fish twice a week. These recommendations were developed by internationally recognized experts, who based their recommendations on hundreds of published studies that looked at the relationship between what people eat and the development of heart disease and stroke.
The diet identified as Mediterranean in the study was high in fiber and vegetables and low in red meat (a major source of saturated fat), with no more than 35 percent of total calories coming from fat. This pattern reflects the current recommendations from the American Heart Association.
Multiple studies have shown that diets high in saturated and trans fats are strongly associated with the development of heart disease, and that diets rich in fruits, vegetables and whole grains are strongly associated with a lower risk of heart disease.
Robert H. Eckel, M.D., a former president of the American Heart Association and a professor of medicine at the University of Colorado Denver School of Medicine cautions the public about jumping to conclusions about the results of the Israeli study.
“Although the people who ate the low carbohydrate/high protein diet lost more weight, it is crucial to consider what diets high in saturated fats might do to your blood vessels and heart over time. The scientific evidence strongly indicates that this type of diet could put people at higher risk of developing heart disease.”
While the weight loss was moderately different between all three groups, the clinical difference was marginal. The American Heart Association stands behind its dietary guidelines as an effect way of losing weight and keeping it off.
The American Heart Association’s No Fad Diet book provides an individualized weight loss program that offers three different strategies for people to choose from, including a low-carb option.
What you need to know right now:
* Eighty-six percent of the participants in the Israeli study were men, and it is unknown how the study’s results apply to women
* The low fat diet used in the study was based on the American Heart Association’s dietary guidelines issued in 2000. Subsequently, the association issued revised recommendations in 2006, which are similar to the Mediterranean dietary pattern in the study, emphasizing high fiber foods, vegetables and limits for foods high in saturated fat, such as red meat
* The Israeli study demonstrates that there are several effective ways to lose weight – people on all three dietary patterns lost weight – but the health effects of eating a high-protein/low carbohydrate Atkins style diet over time are not known
* If you have heart disease, you should avoid any diet that emphasizes eating foods high in saturated or trans fats. A large body of scientific research strongly associates such diets with an increased risk of heart disease.