Why Cardiologists Don’t Recommend Keto for Heart Health

February 17, 2023
Ann Louise Gittleman, PhD, CNS

Ann Louise Gittleman, PhD, CNS

Award-winning nutritionist and New York Times bestselling author.

You may be hitting your goal weight on the keto diet, but is it worth risking your heart health and longevity?

February is Heart Health month, and for good reason – heart disease is still the leading cause of death worldwide. Because an astounding 45 percent of all heart attacks are silent – meaning they have no obvious symptoms – we must look for clues that you may be at risk. And the first place the First Lady of Nutrition looks is your diet.

I’ve recently uncovered some unsettling research that shows that your weight loss diet could be costing you your heart health and longevity. The short-term studies on keto and paleo look promising – quick weight loss, cholesterol reduction, better blood sugar control, and more. But, the long-term studies are very concerning for your heart health and risk of death.

A study of more than 125,000 healthy people spanning more than 25 years shows increased rates of death from all causes on either an animal or vegetable-based low carbohydrate diet like paleo or keto. And it turns out your risk of dying from heart disease is significantly higher on these diets – not lower. Let’s take a closer look at the reasons why.

Dramatic Weight Fluctuations Increase Risk of Death from Coronary Event

If you’ve been trying to lose weight for any length of time, you may recognize the term “yo-yo dieting.” What that refers to is following a diet to lose weight for a limited length of time, then stopping that diet and letting at least some of the weight return. With most keto proponents recommending no more than 6 months of following this highly restrictive diet, by definition it falls under the category of a diet with a high risk of rebound weight gain, and this is not good news for your heart.

Recent studies show that losing and regaining just 10 pounds is enough to increase your risk of sudden cardiac death 3.5 times, even if you are a normal weight. And it also puts you at a 66 percent increased risk of dying from heart disease. According to a study published in the New England Journal of Medicine, if you already have heart disease, an 8.5 pound weight fluctuation from yo-yo dieting makes you 64 percent more likely to have a coronary event, increases your risk of a cardiovascular event by 85 percent, makes death 124 percent more likely, increases the risk of heart attack by 117 percent, and your risk of stroke increases by 136 percent.

This research makes a strong case for slow, steady weight loss on a plan that fits your lifestyle and you can see yourself doing for the long term. According to this study, it takes a full year of modest weight loss of 5 to 10 percent of your starting body weight to see significant improvements in cardiovascular disease risk factors. Considering keto experts recommend no more than 6 months on the diet, the risk of gaining back just 10 pounds of the weight you lost and putting your heart health in jeopardy is much higher than I’m comfortable with.

Changes in Your Gut Microbiome Increase Your Risk of Cardiovascular Disease and Death

Your gut microbiome is a powerful community of trillions of beneficial bacteria and other microorganisms that live together inside your digestive system. Among its many important functions, it helps you break down and metabolize your foods. It turns out that the metabolites that these microbes produce can be a risk factor for cardiovascular disease and premature death.

One metabolite that has been studied extensively for its role in heart disease is trimethylamine-N-oxide (TMAO). TMAO increases your risk of a cardiovascular event by 62 percent and the risk of dying from heart disease by 63 percent. Researchers have found that in those who eat a paleo or keto diet, their levels of TMAO are double the amount of those who eat a typical, less restrictive diet. They also found fewer beneficial bacterial species in the people who ate the reduced carbohydrate paleo and keto diets, which increases the risk of other chronic diseases in the long term.

Low Carbohydrate Diets Increase Your Risk of Atrial Fibrillation

Heart arrhythmias are more common as we age, with atrial fibrillation being the most common, affecting 25 percent of all people in their lifetime. Atrial fibrillation is an electrical problem in the heart and is a leading cause of heart disease and stroke. Eating a keto, paleo, or other low carbohydrate diet increases your risk of this dangerous arrhythmia, according to recent studies.

A diet is considered low carbohydrate when your total carb intake is less than 50 percent of your entire diet. A study of more than 13,000 people spanning more than 20 years found that the lower the carbohydrate intake goes below 50 percent, the greater the risk of developing atrial fibrillation. So those with the lowest carbohydrate intake, like the keto diet, have the highest risk of developing this dangerous heart arrhythmia. The risk doesn’t change whether the primary fats and proteins in the low carb diet are plant-based or animal-based.

A Genetic Inability to Process Animal Fats Increases Risk of Heart Disease

Have you heard of the Apo E gene? This gene controls the production of the protein called apolipoprotein E. This protein combines with fats in your body and forms lipoproteins, which package cholesterol and other fats to carry them through your bloodstream. It also helps break down fats in your liver and your brain.

Everyone has 2 copies of this Apo E gene, and even one copy of the E4 variant increases your risk of heart disease, Alzheimer’s dementia, and more. The E4 gene means that you aren’t able to process saturated fats well and are prone to high levels of oxidized cholesterol, which is the cholesterol that is a risk factor for heart disease. If you have at least one copy of the Apo E4 gene, you need to avoid the saturated fats that are so plentiful on the keto and paleo diets to preserve your heart and brain health. The best fats for you are monounsaturated, like extra virgin olive oil.

Inflammatory Fats Increase Your Risk of Heart Disease and Premature Aging

One of the most popular foods on the keto and paleo diets is bacon. What doesn’t taste better with bacon, right? The problem is that the fats in that bacon are contributing to your toxic load, which leads to heart disease. You may think I’m about to villainize saturated fats, but that’s not where I’m going with this. Saturated fats aren’t the problem – it’s how you’re cooking them that’s increasing your risk for heart disease and premature aging.

When you cook your food using high heat, the proteins or fats react with even small amounts of sugars and form inflammatory molecules through a process called glycation. These toxic, sticky, complex molecules are called Advanced Glycation End Products (AGEs), and not only do they accumulate faster as you age, but they age you faster as they accumulate, and contribute to heart disease. (Men generally eliminate AGEs more easily than women, most likely due to their faster oxidation rate.)

Low levels of AGEs are not a problem. Your body has enzymes and antioxidants that can quickly break these compounds down and render them harmless. But, when you consume too many AGEs through your diet, by your cooking methods, or have high levels of toxins in your body that inhibit your ability to break AGEs down, then they start to accumulate and cause damage to everything from your immune system to your vital organs (including your heart) and all the way out to your skin.

The reason AGEs lead to such a variety of diseases is because they are very versatile in their destruction. Once formed, they clump together and accumulate in your tissues. They cause joint stiffness when they congregate in your joints, contribute to fatty liver disease, and create plaque-filled blockages and blood clots when it’s your blood vessels they target.

Your body is smart, so it tries to mount an immune response to these agitators, which backfires in the form of an overactive, hypersensitive immune system. AGEs cause silent, persistent, inflammation and oxidative damage throughout your entire body, which in turn cause your DNA, cells, tissues, and organs to malfunction, leading to serious chronic diseases that affect every organ in the body – including your liver, kidneys, brain, and heart.

Diet is by far the biggest source of AGEs – even for vegetarians. Animal proteins, by themselves, are more susceptible to AGE formation than any other food. Just like you, animals are exposed to toxins through their environments and accumulate AGEs. This means they are naturally present in the high protein animal products you consume. But when you use high heat methods to cook any of your food (even vegetables), like frying (including air frying), grilling, baking, roasting, or even pan searing, you multiply the AGEs present in the food, increasing your risk of heart disease and other chronic diseases.

Choosing the Diet That’s Right For You – For the Long Term

Diets like keto and paleo are exciting because they produce quick results. But the long-term studies show that the weight loss from these low carb diets is on par with many other diets, so it makes sense to choose the diet you can stick with for the long haul. Take a good look at your lifestyle and realistically assess how often you can cook and which foods you like. Be honest with yourself about the changes you are willing to make to your lifestyle long-term to be successful in your weight loss and health goals, and then start looking for the plan that meets your needs.

My Fat Flush family of plans and my Radical Metabolism plan all have flexibility built into them, so you can tailor them to your individual needs and stick with them for the long haul. They were created with heart health in mind and have been updated as new research comes to light. I’ve set you up for even more success with online support in my Facebook groups – Fat Flush Nation and Radical Metabolism Revolution – with my staff of nutritionists at the ready to help you with the transition to your healthier lifestyle. I also offer my private Inner Circle group for people who need more private, individualized help meeting their goals.

I hope you’ll become another Fat Flush or Radical Metabolism success story, and I look forward to seeing you in one of my Facebook groups soon!

Related Articles and Podcasts

Ann Louise Gittleman, PhD, CNS, is an award-winning New York Times bestselling author of more than thirty books including The Fat Flush Plan series and her latest book, Radical Metabolism. She’s been rewriting the rules of nutrition for more than 40 years and is internationally recognized as a pioneer in the field of diet, detox and women’s health issues. 

For a FREE daily dose of tips and strategies for maintaining healthy weight, conquering insomnia, and much more…check out my Radical Health Tips.

I’d like to meet and greet you on my Facebook groups, so won’t you check us out at the Radical Metabolism RevolutionFat Flush Nation, or my Inner Circle!


  1. Stephen Stokes

    Great article! Everyone needs to read and understand this information. I learned a fewthings here I was not aware of, good job.

  2. Alphonse Van Cauter

    Dear sir

    This statement is aboslutely not true:With most keto proponents recommending no more than 6 months of following this highly restrictive diet.
    They recommend switching between being in keto and not. Better read Dr. Jockers and Mercola on this.

    Saturated fats aren’t the problem – it’s how you’re cooking them that’s increasing your risk for heart disease and premature aging.
    Cooking with vegetable oils are full oxidized. Very bad products. If you cook with vegetable oils there are also producing tremendous amounts of AGE’s.

    It seems that you team have bias based thoughts.

    Keto don correctly have none of the issues that you speak about.

    Regards Alphonse



    People do better when they make lifestyle changes that support weight loss rather than being on or off of a diet. This is what the Fat Flush family of plans does. It gives people flexibility so that can stay on the plan long term and not only lose weight but maintain that loss as well.

    Regarding the saturated fats, animal fats are inherently higher in advanced glycation end products (AGEs).

  4. Spc Lab

    Low Carbohydrate Diets Increase Your Risk of Atrial Fibrillation?
    That was a ridiculous study. It’s an observational study and it wasn’t even a real low-carb diet. The Keto diet is 5% fat, not 50%.

    • TC

      Spc Lab – 5%? Maybe you should use Google more often.
      5-10 come from CARBS not fat as you mentioned.

      On keto here’s what your macronutrients will look like: Roughly 5-10% of your daily calories should come from carbohydrates, 20-25% of your calories should come from protein, and the remaining calories — 70-80% of your daily intake — should come from fat.

  5. John Trefry

    AGE’s are created within the body, primarily via excess glucose and fructose in the blood.. Glycation – root word “glucose”. Primarily caused by excess glucose and fructose, both of which are minimized in the low carb and keto diets. AGE’s are formed when proteins or cells of the body – initially in the endothelium are glycated. It is this “browning” or toasting of the cells that ages us.

    Glycation of external foods are dealt with in the digestive process. Meat has been cooked over fire for hundreds of thousands of years, yet here we are. The effect of this “high heat” creation of AGEs is miniscule compared to the AGE’s created within the body. And AGE’s created within the body are not subjected to the digestive process. They are within the cells.
    I am not a doctor, or a scientist. I am an educated information junkie. If I can find it, you can find it.


Submit a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Pin It on Pinterest

Share This