Ketogenic Diet vs Plant Based Diet: Results and Side Effects

By Scott Burgett | 9.26.18

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The ketogenic diet has hit the public by storm. Rightfully named “Aktins 2.0”, this high-fat,  low-carb diet promises quick weight loss and better health. However, is a low-carb diet the cure all it claims to be?

This article reviews the results and side effects surrounding a ketogenic diet vs plant-based diet.

What is a Ketogenic Diet?

The classic ketogenic diet is a way of eating that allows your metabolism to shift from primarily burning glucose (sugar) as energy to burning ketones. Ketones are created as a byproduct from the lack of carbohydrates in the diet (if you starve yourself of carbs, your liver produces ketones for energy).

Those same ketone bodies produced in the liver, supply fuel for the brain and muscles.

The goal of this diet is to bring yourself into ketosis, which is defined as an abnormal increase of ketone bodies in the body in conditions of reduced or disturbed carbohydrate metabolism. 

Put simply, lack of carbohdyrates for energy creates ketones for energy.

Similar to the Atkins diet, a ketogenic diet is a low (in this case, very low) carbohydrate diet used for weight loss, improving health markers, and fighting disease. The macronutrient ratios of a keto diet can vary, but are usually high-fat, moderate-protein, and very low-carbohydrates.

The Four Types of Ketogenic Diets

Like many diets, there are different versions of a ketogenic diet, including:

• Standard ketogenic diet: Very low-carb (5%), high-fat (75%), and moderate-protein (20%)
• Cyclical ketogenic diet: Five-day keto schedule (using the ratios above), followed 2 high-carb refeeds
• Targeted ketogenic diet: This diet encourages higher carbs around workouts
• High-protein ketogenic diet: Still a high-fat diet (60%), but higher protein (35%) and very-low carbs (5%)

Only two of the four ketogenic diets are studied in the research (SKD and high-protein keto). The cyclical and targeted ketogenic diets are primarily implemented in bodybuilding and other high level athletics, but lack the scientific validity. 

Foods to Eat (And Avoid) on a Ketogenic Diet

Like most diets, a ketogenic diet is extremely restricted. You must diligently track your food (especially carbs) to stay in ketosis.

Eat these foods:

• Meat (red meat, ham, sausage, chicken, turkey, and bacon)
• Fatty fish (salmon, trout, and tuna)
• Eggs (pastured and omega-3 eggs encouraged)
• Cheese
• Butter, cream, and ghee
• High-fat oils and other healthy fats (nuts, seeds, avocados, extra virgin, coconut, and avocado oil)
• Low-carb vegetables (most green vegetables, onions, peppers, tomatoes, mushrooms, etc.)
• Spices (typically salt, pepper, and other seasonings/herbs for taste)
• Sweeteners (stevia, monk fruit, erythritol, etc.)

Avoid these foods:

• Grains and starches (wheat, rice, pasta, etc.)
• Fruit (all fruit, except for small portions of berries)
• Beans and legumes
• Root vegetables (potatoes, carrots, etc.)
• Unhealthy fats (cheap oils like canola or peanut,mayonnaise, etc.)
• Sugary foods and drinks (smoothies, soda, juice, etc.)
• High sugar condiments and sauces
• Any sugar-free or low-fat products (these contain fillers that can knock you out of ketosis)
• Alcohol (most are high in carbs)

What is a Plant Based Diet?

A plant-based diet is loosely defined as a diet that consists of all minimally processed fruits, vegetables, whole grains, legumes, nuts and seeds, herbs, and spices and excludes most animal products, including red meat, poultry, fish, eggs, and dairy products.

The focus of a plant-based diet is eating a variety whole foods,and not adhering to strict macronutrient percentages like the ketogenic diet. Glucose is the primary fuel source when eating a plant-based diet, so carbohydrates are a primary source of nutrients.

Eating a plant-based diet consists of moderate/high-carbohydrates (45-65%), moderate-protein (15-30%), and low/moderate-fat (20-30%).

Foods to Eat (And Avoid) on a Plant Based Diet

A plant-based diet is simple to follow. If it has an animal product, exclude it. Use the guidance below for a more comprehensive list of foods.

Eat these foods:

• Plant-based meat alternatives (tempeh, tofu, seitan, etc.)
• Whole grains and starches (whole wheat pasta, sweet potatoes, etc.)
• Beans and legumes (beans, peas, lentils, etc.)
• Any and all vegetables (broccoli, peppers, kale, etc.)
• Any and all fruits (bananas, berries, citrus, etc.)
• Healthy fats (nuts, seeds, avocados, etc.)
• Spices, seasonings, and herbs
• Sweeteners (stevia, monk fruit, erythritol, etc.)

Limit these foods:

• Sugary foods and drinks (soda, juice, sugar-flavored beverages, etc.)
• Processed carbohydrates (chips, cookies, candy, etc.)
• Unhealthy fats (dairy-free butter, cheap vegetable oils, etc.)
• Cooking oils (extra virgin olive oil, coconut oil, canola oil, etc.)
• Alcohol (spirits, beer, wine, etc.)

Avoid these foods:

• Read Meat
• Fish
• Poultry
• Pork
• Turkey
• Eggs
• Dairy (cheese, butter, cream, yogurt, etc.)
• Condiments containing dairy or eggs
• Any packaged foods containing meat, poultry, fish, eggs, or dairy

Ketogenic Diet Effects: Weight Loss

A ketogenic diet has a very positive effect on weight loss.

This 2008 study concluded that those who followed a low-carbohydrate ketogenic diet for 24 weeks “led to greater improvements in glycemic control, and more frequent medication reduction/elimination that the low glycemic diet.”

The low-glycemic diet however was not plant-based, and did include meat, dairy, and eggs. Nonetheless, the keto group lost 24 lbs compared to 15 lbs for the control group.

An earlier study published in 2004 showed that a high-fat keto diet positively affected the BMI of 83 obese patients. Patients started at an average BMI of 38 (considered extremely obese) and dropped to a BMI of 32 (considered obese) in 24 weeks.

Though there was no control group in the study, the results speak for themselves; a keto diet can help you lose weight.

Additionally, the authors’ labeled this a “long-term” study, even though the study only took place for six months in duration. They also stated “the present study confirms that it is safe to use a ketogenic diet for a longer period of time than previously demonstrated.”

The Keto Fallacy

Six months is not long-term. Legitimate long-term studies take place over the course of years and not months. 

This begs the question: Is the reason long-term studies are not available because a ketogenic diet is extremely restricted? 

Authors from this study certainly think so. They concluded that a “ketogenic diet was difficult” and had “high dropout rates”, regardless of the positive results seen in test subjects. 

This result is common among low-carbohydrate diets. The focus is on ratios and not real food, which confuses dieters and ultimately discourages them from continuing.

Plant Based Diet Effects: Weight Loss

On the other hand, plant-based diets have also shown positive outcomes for weight loss. A study published by the American Medical Association tested the eco-Atkins (low-carb plant-based diet) vs a high-carb plant-based diet.

The authors provided all food to the study participants, which is extremely rare in the scientific literature simply because it is expensive to feed hundreds of patients of several weeks. So this increases the efficacy of the results because researchers make sure the patients are adhering to the dietary protocols.

After 30 days, both groups lost an equal amount of weight (8.8 lbs).

The low-carb group ate 26% of their food intake from carbohydrates, while the high-carb group ate 56% carbohydrates. The fat content was 43% (low-carb) and 25% (high-carb).

These results show us that it’s not exclusively about the macronutrient profile of our diets, but also nutrient density. Simply put, a nutrient dense food would be a potato, while a potato chip would be a nutrient poor food.

Regardless if the diet is high-fat or high-carb, eating nutrient dense foods seems to play a large role in weight loss.

Vegans Have the Lowest BMI

Another extensive study that took place between 2002-2007 observed the dietary patterns of the 7th Day Adventists in Loma Linda, CA. Most people within this group (just shy of 100,000) ate either a vegan or vegetarian diet, while a small number were non-vegetarians.

The vegans were the only group that had an average BMI in the normal range (24.1). Both the vegetarian and meat-eating groups had an average BMI classified as overweight (26.1 and 28.3), lending to the conclusion that consumption of animal foods leads to a heavier average weight.

Although this was an observational study (analyzing data vs conducting an experiment), it showed meat eaters walking the line between being overweight and obese.

It’s a powerful illustration of how those who eat a nutrient dense, plant-based diet can achieve a healthy body weight without dieting.

Keto Diet Effects: Health Biomarkers

Many studies testing the ketogenic diet show positive correlations around weight loss, but what about health biomarkers? Those include cholesterol, triglycerides, blood pressure, etc.

This study published in 2006 looked at long-term effects of a ketogenic diet in obese subjects with high cholesterol. Sixty-six test subjects began the study, while only 49 managed to finish.

Throughout the entire 56 weeks of research, the subjects showed significant positive changes in their HDL (good) and LDL (bad) cholesterol, as well as triglycerides (fat in the bloodstream).

More specifically, HDL increased, LDL decreased, and triglycerides decreased; all great signs of health in obese patients with high cholesterol.

Another smaller scale keto study that tested type II diabetics showed a “significant improvement of glycemia” (a measure of glucose in the blood). Of the 21 participants, 17 reduced or discontinued their diabetes medication in just four months.

Sounds effective, right?

Well despite the positive results, there was no control group. A control group is extremely important  because it helps show a causal relationship to the test group. In other words, it increases the validity of the variable being tested (in this case being a keto diet).

So although the group made improvements, it’s impossible to tell whether eating a ketogenic diet was the sole cause of improvements.

Plant Based Diet Effects: Health Biomarkers

Leading plant-based physician Dr. Neal Barnard published a study that put type II diabetics on a low-fat, plant-based diet for 74 weeks. This randomized, controlled clinical trial (considered the gold standard of research) showed a vegan diet could lower total cholesterol, LDL cholesterol, A1c, and fasting glucose.

Additionally, 71% of the subjects eating a low-fat vegan diet were able to alter their diabetes medications compared to only 58% on the conventional diet. Participants eating the vegan diet ate 75% carbohydrates, 15% protein, and ~10% fat.

They specifically avoided high-fat plant foods and were encouraged to eat low-glycemic foods such as beans and green vegetables to help with satiety. This was all done on an unrestricted basis, where participants could eat as much as they pleased.

This is yet another example illustrating how a nutrient dense diet, in the case carbohydrate heavy, can positively affect our health.

Along with the study above, more positive associations on blood markers are demonstrated through plant-based diets. A study published in the Archives of Internal Medicine concluded that low-moderate intake of carbohydrates showed reductions in LDL-C and blood pressure ratings. 

In spite of the criticism surrounding plant-based diets, studies like the ones mentioned in this article, continue to show positive associations when measuring health biomarkers.

These studies continue to carry out the highest standards of research, include large sample sizes, and test on a variety of variables.

Where the Classic Ketogenic Diet Falls Short

Up to this point, the ketogenic diet looks like it can help you lose weight and lower your chances of chronic disease. It might seem like a bulletproof way of eating.

Science says different, however. Even with these tempting results, a keto diet still comes with unpleasant baggage.

Keto diet health shortfalls:

• Low carbohydrate diets consistently show a higher risk of mortality
• High animal protein intake is positively associated earlier mortality and coronary heart disease
• Long-term consumption of red meat is associated with an increased risk of total mortality
• High red meat intake has been linked with kidney failure
• Red meat, specifically processed meats like bacon and sausage are linked to increased risk of cancer

Keto diet environmental and sustainability concerns:

• Meat-based food systems require more land, energy, and water compared to plant-based diets
• Animal agriculture is responsible for 18 percent of greenhouse gas emissions, more than the combined exhaust from all transportation
• Animal farms are responsible for 73 percent of the ammonia released into the air that causes respiratory problems in humans
• Chicken and pork, considered resource efficient meats still need three times more land than beans
• Three-fourths of the world’s fisheries are either exploited or depleted

Continuing to recommend eating animal protein and fat is an unsustainable solution for our planet. Growing and caring for animals drains our planets natural resources at an unprecedented rate. 

If you are going to try a ketogenic diet, do it plant-based.

Plant Based Ketogenic Diet

Following a plant-based ketogenic diet is a sustainable solution for a very low-carb approach to eating. 

When engaging in a plant-based ketogenic diet, macronutrients are 5-10% carbohydrates, 70-80% fat, and 15-20% protein intake. 

Unfortunately, most plant foods are  high in carbohydrates. The list below outlines acceptable foods on a plant-based ketogenic diet.

Eat these foods on a plant-based keto diet:

• Plant based proteins (tofu, tempeh, seitan, protein powders, etc.)
• High-fat oils (coconut oil, extra virgin olive oil,  etc.)
• Plant based “dairy” (vegan cheese, unsweetened coconut yogurt, etc.)
• Nuts and nut butters (almonds, walnuts, peanut butter, almond butter, etc.)
• Seeds (hemp seeds, chia seeds, etc.)
• Low-carb vegetables (broccoli, zucchini, peppers, onions, etc.)
• Leafy greens (spinach, kale, collard greens, etc.)
• Fruits (berries only and limit to ½ cup serving per day max)
• Spices, seasonings, and herbs
• Sweeteners (stevia, monk fruit, erythritol, etc.)

Avoid these foods on a plant-based keto diet:

• Legumes (any and all beans, peas, lentils, etc.)
• Root vegetables (potatoes, carrots, etc.)
• Fruit (all fruit except for low glycemic berries)
• Liquid or solid sugars (agave, maple syrup, sugar, etc.)
• Sugary drinks (smoothies, juices, etc.)
• Grains (pasta, bread, oats, corn, wheat, rice etc.)
• Any sugar-free or low-fat products (these contain fillers that can knock you out of ketosis)
• Alcohol (most are high in carbs)

A plant-based keto diet requires you to avoid many foods that are staples in a normal plant-based diet. However, using digital tools like cronometer.com or MyFitnessPal can help you track your food to stay within the macronutrient limits.

Final Thoughts on a Ketogenic Diet

One question still lingers for a keto diet: what are the true “long-term” effects?

Unfortunately, we won’t know for another several years simply because the research has not caught up with the hype. Yet that’s typical for diets; anecdotal evidence hits the media by storm before research can confirm it.

Most studies on a meat-based ketogenic diets last six months or less, and few studies have looked at the effects of a plant-based ketogenic diet. 

In conclusion, a ketogenic diet can aid in weight loss, improve insulin sensitivity, and have other positive effects on our blood biomarkers, it’s still very risky and hard to follow.

Have you followed a ketogenic diet before? Share your experience in the comments.