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I'm A Cardiologist & I Tried A Vegan Keto Diet. Here's What Happened

Joel Kahn, M.D.
Cardiologist By Joel Kahn, M.D.
Dr. Kahn is the founder of the Kahn Center for Cardiac Longevity. He is a summa cum laude graduate of the University of Michigan School of Medicine and is a professor of medicine at Wayne State University School of Medicine.
I tried the Vegan Keto Diet
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I have long been a proponent of plant-based diets. In fact, I have been following one for 42 years, 30 of which I have been a cardiologist. In particular, I have taught, written about, lectured on, and prescribed plant-based diets naturally low in fats and generally without oils.

So, naturally, I have been an outspoken critic of conventional animal-based high-fat keto diets. However, I believe most people are trying to eat generally healthy, avoid disease, be kind to animals and the planet, and maintain a healthy weight. And, as Dean Ornish, M.D., highlighted in his book The Spectrum, there is a continuum, perhaps including a vegan ketogenic diet, that healthier subjects might adopt. So, I decided to try a vegan version of the keto diet. Here's what happened.

What is the vegan keto diet?

First, let me explain what exactly "vegan keto" means. As you may know, a ketogenic diet is a high-fat, low-carbohydrate diet meant to shift your body into nutritional ketosis. Ketosis is the state in which the body preferentially burns fat over glucose for fuel. This is typically accomplished by eating fatty meat and fish, full-fat dairy, vegetable oils, and other high-fat foods.

The exact macronutrient ratios of a ketogenic diet can vary but typically fall within the ranges of:

  • Fat: 65% to 85%
  • Protein: 15% to 35%
  • Carbohydrate: 0% to 10%

A vegan keto diet follows the same principles but without any animal-derived products, like meat and dairy. A typical meal might look like a plate of arugula, freshly sliced avocado, walnuts, lupini beans, hemp hearts, cubes of organic tofu, spices, tahini or nut butters, and a healthy coating of EVOO.


The science behind the vegan keto diet.

I was first introduced to the idea of a vegan keto diet about five years ago by Carrie Diulus, M.D. As a spinal surgeon, Diulus performs long operations with the added challenge of managing type 1 diabetes. She told me that a plant-based diet high in fats and low in net carbs provided her excellent diabetic control and stable blood sugar for hours at a time.

Diulus is not alone in her praise of the vegan keto diet. There are other nutrition researchers that tout the benefits of a high-fat plant diet, particularly when cycled on and off (although Diulus selects this pattern continuously). For example, David Jenkins, M.D., Ph.D., famous for creating the glycemic index, developed and studied an "Eco-Atkins" diet. In the study, he compared a low-carbohydrate, high-fat plant-based diet (the "Eco-Atkins") with a control diet, which was a high-carb lacto-ovo vegetarian diet. The study reported that after six months, those on the high-fat "Eco-Atkins" diet saw more weight loss and better cholesterol measurements than the control group.

Another example of a higher fat plant diet is the Prolon Fasting-Mimicking Diet developed by the world-famous longevity scientist Valter Longo, Ph.D. On this diet, you eat prepared foods providing 800 calories a day for five consecutive days, with about 60% of calories coming from whole plants rich in fat like Spanish olives and nuts. When this diet was cycled five days a month for three months in a randomized trial, important changes in biomarkers, including stem cell release and the inflammation marker hs-CRP were identified supporting a promotion of health and health span. I have tried Prolon myself, as have hundreds of my patients.

What happened when I tried the vegan keto diet.

Over the past two years, I have followed a vegan keto diet for several weeks at a time. During this time, I have had the most advanced heart and carotid artery imaging and advanced laboratory studies done and have no plaque in my arteries. I also confirmed that my body had entered ketosis with both urine and breath measurements.

So what happened? I felt energetic, but no more than usual. I felt clearheaded, but no more than usual. My workouts were strong, but no more than usual. I did lose some weight, despite eating a lot of food. I did maintain a high fiber intake while on the diet and added blackberries and raspberries for a bit of sweet flavor. Most alcoholic drinks, without mixers, are permitted on a keto diet. I favor European red wines sourced to be ultralow in sugar, which do not break the ketotic state. Tequila and vodka are other options, though.

Will I keep eating this way?

Overall, I am split. I still strongly defend high complex-carbohydrate diets that are naturally low in fat calories. This type of diet has been shown to prevent many chronic health conditions. In fact, the Okinawan diet, from one of the Blue Zones of longevity, also follows this dietary pattern with stunningly low rates of chronic disease.

However, for the healthier person who has hit a roadblock in weight loss or is looking for a few days of a different diet plan, exploring a higher fat plant diet emphasizing mainly plant foods is likely fine and may ultimately be proved to be healthy.

More research is needed on the vegan keto diet, and it is worth noting, some persons might experience a jump in their blood cholesterol levels when raising the fat content of their diet. Remember, there are some saturated fats in avocados and even in olive oils. However, there is probably little risk in trying a vegan keto diet for most healthy persons, especially in short spurts. Cycling in and out of ketosis, as taught by Longo and others, may be better than striving for a continual ketotic state, with some exceptions. Time will tell.

Joel Kahn, M.D.
Joel Kahn, M.D.
Dr. Joel Kahn is the founder of the Kahn Center for Cardiac Longevity. He is a summa cum laude...
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