Topics » Nutrition Science » Experts Agree: Keto and Vegan Keto Diets Should Be Avoided
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You have surely heard the term keto mentioned in water-cooler conversations at the office and popping up on product labels. But the concept of a ketogenic diet (keto for short) is nothing new. Remember Atkins and the low-carb craze? Keto in principle is the same. So does the keto diet promise live up to the hype? And is a vegan or plant-based keto diet a better alternative?

We spoke to multiple experts from diverse backgrounds to cut through the hype and dig into the science and truth about all things keto.

First of all, what is a keto diet? The keto diet is premised on a severe reduction in carbohydrates, forcing your calories to come from fats and proteins instead. Initially, upon starting the keto diet, the body utilizes its carbohydrate stores to maintain energy needs and blood glucose, but as the diet is maintained longer and longer, these carbohydrate stores are depleted and the body begins producing ketone bodies derived from fats to sustain energy needs.

While some studies have shown that rapid weight loss can occur on keto—a common reason for people adopting the diet—other programs, including low-fat, DASH, Mediterranean, and plant-based diets—have shown to be just as effective or better.

David Sonenberg, MS, RD, a registered dietitian and founder of Healthier Appetite, provides some perspective on the keto craze and has tracked numerous studies about ketogenic effects on the body.

“Followers of keto diets have higher rates of vitamin and mineral deficiencies, constipation, gastro-intestinal disorders, and are at higher risk for heart disease,” says Sonenberg. “A 2013 meta-analysis of 272,216 people concluded, ‘low-carbohydrate diets were associated with a significantly higher risk of all-cause mortality,’ meaning they have significantly shorter lives.”

See, the trade-off to a reduction in carbohydrates is an increase in fats and proteins, which is where you must derive your calories on a keto diet. “You don’t need to wait years to see the impact; within hours of eating a high-fat meal, there is a measurable negative impact on arterial function, making your heart work harder,” notes Sonenberg.

In the popular documentary The Game Changers, a simple, yet compelling example demonstrates the nearly immediate effects on the body after meat consumption. Football players ate a plant-based meal and a meat-based meal and then had their blood levels measured after each. After the meat-based meal, players’ blood plasma was visibly murky (vs. following the plant-based meal, where blood plasma was clear/normal).

OK, But What About a Vegan Keto Diet?

Vegan or a plant-based keto operates on the same principles of carbohydrate depletion. Most people have to limit their net carbohydrates (total carbs minus fiber) to about 40 grams or less to remain in ketosis, which can be difficult when also limiting yourself to only plant-based foods. Sonenberg references a study from the Harvard School of Public Health that compared low-carbohydrate diets from plant or animal sources and found that low-carbohydrate plant-based diets were associated with lower all-cause mortality than low-carbohydrate omnivore diets.

What Foods Are Included in a Vegan Keto Diet?[1]

Coconut products: Full-fat coconut milk, coconut cream, unsweetened coconut.
Oils: Olive oil, nut oil, coconut oil, MCT oil, avocado oil.
Nuts and seeds: Almonds, Brazil nuts, walnuts, hemp seeds, chia seeds, macadamia nuts, pumpkin seeds.
Nut and seed butter: Peanut butter, almond butter, sunflower butter, cashew butter.
Non-starchy vegetables: Leafy greens, Brussels sprouts, zucchini, broccoli, cauliflower, peppers, mushrooms.
Vegan protein sources: Full-fat tofu, tempeh.
Vegan full-fat “dairy”: Coconut yogurt, vegan butter, cashew cheese, vegan cream cheese.
Avocados: Whole avocados, guacamole.
Berries: Blueberries, blackberries, raspberries and strawberries can be enjoyed in moderation.
Condiments: Nutritional yeast, fresh herbs, lemon juice, salt, pepper, spices.

Dr. Jonny Lisano, Exercise Physiology and ACSM Certified Exercise Physiologist, points out that one issue with a vegan keto diet is it severely limits the options for fats and proteins that you would need to consume to keep up an adequate calorie intake and get essential nutrients. “You’ll need to ensure that you are getting all of your essential nutrients,” notes Dr. Lisano. “However, as with any dietary choice, this decision is up to you. No balanced diet is ever complete without fruits and vegetables.”

What’s the Verdict on Any Type of Keto Diet?

Dr. Lisano: “The keto diet is not a diet that I would recommend partaking in for a long period of time. As your body reduces your glucose stores, you divert metabolic intermediates that help you process carbohydrates to instead maintaining your blood glucose levels to prevent hypoglycemia. This can greatly reduce your capacity to handle and process carbs after ending the diet and cause metabolic issues. I would only recommend the long-term use of the keto diet under the strict guidance and supervision of your healthcare physician, RD, and a certified exercise physiologist monitoring the balance of your daily activity, food intake, and health markers.”

Dr. Lisano warns that, “With a prolonged keto diet, ketoacidosis may set in.” The presence (and the processing) of excess ketones to maintain your energy can acidify the blood, causing confusion, motor impairment, and, in severe cases, even death.

Soneneberg: “Based on the studies I have read, I cannot recommend the keto diet as safe. I recommend a plant-based diet that is rich in fruits, vegetables, legumes, seeds, and nuts and is low in refined carbohydrates and processed ingredients. There are far safer and sustainable diets for weight loss available.”

Hopefully the information here helps you better assess the efficacy of the ketogenic diet. Everyone has their own personal reasons for selecting a diet and food lifestyle that suits them. Always remember to read the science, take input from the experts, and cut through the marketing hype. Perhaps, though, Micheal Pollan said it best: Eat [real] food. Mostly plants. Not too much.

Learn more about the ketogenic diet from our keto article series:

  1. What Is the Ketogenic Diet?
  2. Is the Ketogenic Diet Natural for Humans?
  3. Does the Ketogenic Diet Really Work for Weight Loss?
  4. Can the Ketogenic Diet Reverse Type 2 Diabetes?
  5. Can the Ketogenic Diet Cure Cancer? What Does the Science Say?



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