Keying in on Ketogenic Diets

if you are interested in losing weight,  the ketogenic diet as popularized by the late Dr. Robert Atkins, has had its share of controversies.  The diet, characterized by extreme carbohydrate restriction (usually less than 50 grams per day) results in depletion of our primary energy source, glycogen (glucose reserves stored in liver and muscle).  After several days of a very low carb, high fat diet, the liver converts fatty acids into ketones that enter the bloodstream and urine.  Certain ketones (e.g., acetone) have anti-seizure properties and in fact, the ketogenic diet has been prescribed for many years in the treatment of seizure disorders.  The Atkins diet can also result in significant weight loss in at least 2 ways.  First, by restricting carbohydrate intake from ~50% of daily calories to 10% or lower; in fact, the average caloric intake in Phase 1 of the Atkins diet is ~1500 calories (300-500 calories lower than generally consumed by women and men daily). Second, with accumulation of ketones, ketosis sets in and fat breakdown is accelerated. Not surprisingly, significant weight loss (2+ pounds per week) is readily achievable on a ketogenic diet and in the short-term (3-6 months) represents an effective weight losing platform.  In addition to weight loss, other positive aspects of a ketogenic diet (and correlated to weight reduction) are metabolic improvements. They include reduction in glucose, lipids (most notably triglycerides) and blood pressure.  However, keep in mind that ketogenic diets also have potential side effects ranging from lethargy, muscle wasting (carbs are required for muscle health and function), digestive issues such as constipation (due to lack of fiber) and halitosis (ketones induced bad breath).

Unfortunately, considerably less is known following decades exposure to ketogenic diets especially as it relates to the heart.  As a cardiologist, I was surprised to learn that the late Dr. Atkins in fact suffered from an enlarged heart and congestive heart failure.  Could this have been related to an associated nutritional deficiency that can trigger heart failure,  such as selenium or other micronutrients? A new study conducted in Finland shares this concern.  Of the nearly 2500 middle aged subjects followed over 2 decades, consuming the most animal based protein was associated with a more than 40% increased risk of heart failure. In contrast, increased consumption of protein from fish was not correlated with significant risk of heart failure and some studies have suggested that fish or fish oil supplementation may even protect against heart failure.

While the Atkins diet results in more weight loss than other popular diets over a 12 month period, you need to decide what might work best for you. Along these lines, if you are considering a ketogenic diet over a short-term duration, I would recommend that the dietary fat component contain low amounts of saturated fat, based upon our recent American Heart Association Presidential Advisory Statement on dietary fat and cardiovascular disease,   Otherwise, I generally recommend that my patients take a more moderate low carb weight loss approach as outlined in “Heal Your Heart” where your favorite foods are moderated rather than restricted and without downside risk.

Michael Miller, MD is Professor of Cardiovascular Medicine at the University of Maryland School of Medicine in Baltimore, Maryland USA.  He is a member of the American College of Cardiology Nutrition Workgroup and the American Heart Association Council on Lifestyle and Cardiometabolic Health.