Heart Smart Living
Heart Smart Living

Cardiologist, author, and heart health expert Dr. Sarah Samaan offers advice on how to live a heart smart life.

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The Perils of a Low Carb Diet

Low carbohydrate, high protein, high fat diets have been around since William Banting started the fad in the 1860’s. Modern versions include the Atkins Diet, the Zone Diet, and the South Beach Diet. Without a doubt, our typical Western diet, bloated with endless loaves of white bread, mounds of pasta, and buckets of snack foods, provides far more simple carbohydrates than our body can safely handle. But when we trade out healthy complex carbs, including antioxidant and fiber-rich fruit, vegetables, and whole grains for slabs of bacon and sides of beef, can we possibly be doing ourselves any good?

There is no doubt that people can and do lose weight on these low carb diets. As a result, blood pressure and cholesterol levels often fall. But when the effects are carefully studied, it turns out that the weight loss experienced is due in part to water weight, and in part to calorie control. Since these diets are usually easier to follow than the traditional low fat diet (which comes with its own negative health consequences), people are often more willing to stick with them for a while. Nevertheless, having been in practice for nearly 20 years, I can tell you that I have rarely if ever seen anyone who has lost weight this way keep it off for more than a year or so.

As a cardiologist, I have always been concerned about the high levels of saturated fats inherent in most of these diets. Most saturated fats come from red meat and full fat dairy products, although tropical oils (including coconut and palm oil) are also potent sources. In the laboratory, exposing arteries to this type of fat has been shown to cause constriction of blood vessels.

A new study from Dr. Luis Masana and colleagues, published in the British Journal of Nutrition, evaluated the effects of a low carb, high protein, high fat diet on the blood vessels of 247 men and women who were considered to be at intermediate to high risk for developing heart disease. Not surprisingly, the more rigidly they adhered to the diet, the more abnormally their blood vessels responded to stress. In an earlier study, the same group of researchers had found the opposite (and much healthier) effect in people who followed a Mediterranean diet. 

It’s easy to get caught up in the hype and excitement of the latest trendy diet, but it’s important to maintain a healthy perspective. Saturated fat, especially from red meat, has been linked to a higher risk for heart disease, stroke, dementia, and cancer, while a Mediterranean diet has the opposite effect. By cutting out processed foods and limiting “white” carbs (including white bread, white rice, white pasta, and white potatoes), while welcoming fruits, veggies, and whole grains, you’ll be giving yourself the best of  both worlds.


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Tags: Diet and Heart Health

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About the Author


Dr. Samaan is an acclaimed cardiologist, writer, and heart health educator.