Keto and the heart – Adapt Your Life® Academy



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Keto and the heart

I’m going to explain what the heart does and provide a refresher. It’s a complicated organ and if you don’t know anything about the heart, that’s okay. You know that it’s a pump, and that you need it.

Keto reverses heart failure

I’m going to present three cases of people whose heart failure got better or was reversed. It doesn’t have to do with the coronary arteries; it has to do with the squeezing of the muscle.

Overview of the heart

The heart can be thought of as having three main components. There’s a fourth one – the endocrine part – that I won’t get into because there’s nothing known about a keto diet and the endocrine function of the heart that I’m aware of. First, most of you are probably aware that the heart muscle functions as a pump. The little chambers are called the atria, and the big ones are called the ventricles. Secondly, in terms of coronary artery disease, or blockages, or when people talk about something being good or bad for the heart, they usually don’t talk about the heart muscle; they talk about the blood flow to the heart muscle or the coronary arteries themselves. Blood moves from the outside to the heart itself through the coronary arteries. The third thing that has to do with pacemakers and palpitations, things like atrial fibrillation, which is really the electrical system of the heart, the conduction system. How it all fits together. The sound of your pumping heart is actually the top of the heart contracting and then the bottom, so it’s like a preload and then a squeeze. That’s a fascinating electrical system that I’ll go into as well.

The heart pumps blood through the circulatory system

This is now being taught in middle school in the U.S., that there’s a circulatory system. It is fascinating to know the history of how this was figured out. For a long time, it was thought that the blood went away from the heart and then went back to the heart, like the ocean and a tide coming in and out. It was the doctor who put the hand or finger on the veins to show that there were valves, and then it was really just going in one direction. That was relatively recently. Oxygenated blood comes out of the lungs, and then the oxygen is delivered to the organs. Blood that is not oxygenated comes back to the right side of the heart. The pumping goes at the same time left to the right side.

The right side of the heart pumps the blood through the lungs – called the pulmonary arteries – and gets oxygenated. When you take a deep breath and feel the oxygen hitting the blood it moves through the pulmonary veins. It also moves through the aorta here at the beginning, and then comes around the side. This is called systemic circulation. And then there is pulmonary circulation here. This is all energized by this pump which is just constantly going. I got into medicine actually because I was just curious about how things worked and I’m still learning today. There’s something you need to know about that pump. It’s a simple number to remember: about half of the blood is ejected with each pump. That’s called the ejection fraction (EF). The percent of blood pumped per contraction is about 50 or 55 percent. A normal EF is 55. The heart doesn’t totally squeeze 100% out but about 50%, and that’s a good, normal amount. If it’s 30 percent, 20 percent, 15 percent, that’s a really weak heart that’s been damaged. You don’t need to know the details of valves of the heart; I think that needlessly complicates it right now.

Hearts attacks

A heart attack is a sudden reduction in blood flow to the pump. The pathophysiology of a heart attack – the damage or the process that occurs – is totally different from the muscle itself. It’s in the artery going to the heart muscle, feeding the oxygen that’s in the blood to the heart muscle. When we talk about coronary artery disease, we’re talking about the plaque buildup and blood clots in the arteries that are going to the muscle. We are trying to prevent the heart muscle from dying when we’re trying to prevent heart attacks or prevent heart damage from coronary artery disease. The arteries provide the blood and nutrients to the heart muscle itself.

Coronary arteries

There are three major coronary arteries that can be affected with coronary artery disease. The left main has two branches that come from one. If you have a blockage here, that’s colloquially called the “widowmaker,” because if you block this, the blood to the big part of the heart that pumps out to the body may stop or be totally damaged. That is not compatible with life if your heart stops for a period of time. So that’s the left main artery. The left anterior descending artery comes down the left side of the heart and then the left circumflex goes around to the back of the heart. The right coronary goes to the back side of the heart as well, and the right artery is actually not so important because it’s not providing blood to the major systemic muscle. Remember you have those two muscles. Of course, it is important, but the damage to the left side can do worse in terms of heart failure because the pump isn’t going to be working as well if you’ve had damage to the heart. You might have a spasm of these arteries that have temporary blockage and have chest pain and the symptoms that come with a heart attack, but then the spasm might relieve itself, and then the pain goes away, and you don’t actually have damage to the heart. You might have a blockage that gets reversed through a catheterization, where the doctors open it up and let the blood flow get in there before there’s any damage to the heart. It matters how long the duration of the blockages or the lack of oxygen are – you want to get attention as soon as you can.

When doctors look at an x-ray view of a heart catheterization, they won’t actually look inside the arteries, but will use a dye to see what is going on. With this view you are inferring a lot in terms of what percent is blocked and where the blockages are. That’s why I’ll hear people tell stories about one doctor who said this, one doctor said that – even though it’s the same test, you might have different interpretations. That’s because it’s not a perfect test, although that’s the best test we have in terms of urgently visualizing where the blood flow is and where it isn’t.

Opening blood flow with balloons and tubes (stents)

You might have a blockage like a clot or plaque. You might get a catheter balloon put in there to relieve the blockage itself and open it up. It is inserted to go up the coronary artery so the blood flows again. You might have a stent (which looks like a Chinese finger trap toy) put in there to bring the blood flow back. This process and what goes on there really hasn’t changed much since I was in training in the 1980s and 90s. There’s quite a lot of controversy over whether putting a lot of stents in really is superior to just managing people medically, because stents do block again. Duke University (where I work) is very cardiology-friendly and there are a lot of stents put in, but some of the really critical medical cardiologists are not so convinced that they really do better than just monitoring folks and treating them medically. (With medication rather than surgical procedures.) Then, of course, if you have multiple blockages where a lot of stents couldn’t be used or there’s a blockage in every artery, you would probably be referred for heart bypass surgery where you’re actually bypassing the blockages on more than one artery at a time.

What coordinates the pump muscles?

The cardiac conduction system coordinates everything; it is nervous tissue (part of the nervous system), not muscle or arteries. There’s a sinoatrial (SA) node that is basically like a metronome that fires out. It’s under control, but can speed up and slow down by the nervous system and by hormones like adrenaline. This node will send out a signal to contract the atria. That signal will then hit the atrioventricular node, which picks up the nervous signal baton, the electrical stimulation, and then sends the signal down to the ventricle heart muscle in a coordinated fashion that gets the muscle to contract all at once.

Cardiac electrophysiology

The conduction system itself needs to be supplied with blood and nutrients. The coronary arteries supply the SA and AV nodes. If you have coronary artery disease with blockages, some of these arteries might lop off one of the conduction systems and you might get arrhythmia or an uncoordinated contraction, which gets into these things called bundle branch blocks. I spent years learning how to read EKGs. The wonderful thing is that there are units even available at airports which will read, diagnose, and administer treatment based on these readings. These readings can help us identify premature ventricular contractions (PVCs) and premature atrial contractions (PACs). As we get older, these occasionally happen and it’s no big deal. You might, however, get a Holter monitor which you take home with you and wear it, sometimes for weeks, if it’s an irregular rhythm. We can also pick up on atrial flutters or atrial fibs (sometimes it’s hard to tell). If the blood doesn’t flow well, you will be dizzy, not feeling well, and a goner without medical treatment. This might be all too much information, but I think it’s important to see that there are benign things that we don’t worry about. We do worry about arrhythmias, though. So if you’re having irregular heartbeats, you need to get it checked out with an EKG.


Fortunately, the conduction system can be replaced – these are called pacemakers. The pacemaker could be as simple as putting a lead in a certain place which tells the heart to beat. It’s suddenly an electrical signal to the muscle and the muscle responds. Nowadays the more sophisticated ones have an electrode lead for the atrium and the ventricle. It’s really amazing. Then the battery is put under the skin, typically in the upper chest. The SA node and AV nodes are the anatomic pacemakers; when the electrical conduction system fails, you can just replace it with this artificial one.

Left ventricular assist devices

When the pump fails, you can actually put in an artificial heart or do a heart transplant. It’s pretty heroic. Duke has one of the largest programs of left ventricular assist devices (LVADs) in the world. I started getting referrals from people who had no pulse. It is basically a pump that is implanted and it has a continuous flow. A person might have no pulse – the heart muscle itself is so weak it’s not contracting, yet the pump takes blood from the ventricle here and squirts it into the aorta. It is really amazing. Lately the battery pack is on the outside and is connected through an internal wire.

I started helping these folks lose weight in order to get heart transplants. I am seeing people who are too heavy to get a transplant. Obesity is a prevalent culprit in heart failure as well – a lot of these people need a heart transplant but they’re too big and it’s too risky to have it done. There’s a transplant list and in order to get on the list you need to lose weight. Many of these people need to lose weight. It’s complicated to take care of these patients, but with my internal medicine training I’m comfortable taking care of people with heart failure. You also have to watch the anticoagulation because as you might surmise, the plastic tube here will clot up if the blood is not anticoagulated. Then you have to watch your salt intake. For heart failure or for high blood pressure you want to monitor salt, so I have a modified version of the keto diet that I apply with people like this.

Keto and heart failure

So, what about the keto diet?

Case study 1:

This first case is a 43 year old female who had acute systolic heart failure. She had a defibrillator placed, which is common. That’s a device that will shock the person if the heart has one of those terrible arrhythmias. It’ll do it when they’re at home again; it senses it and gives the treatment. After this patient was hospitalized, she lost weight watching her calories but she hit a plateau. She learned from her father about the keto diet and then lost 15 pounds over 12 weeks. She found me at Duke. She had weighed about 300 pounds in her 5’2” height frame for about five years. Nobody could figure it out. Her coronary arteries were clean, meaning there was no blockage and no one could figure out what caused the heart failure except the obesity. You’re pumping against all this extra tissue. When she was initially diagnosed, she had an ejection fraction of 20 percent, which put her in a severe heart failure category. That improved over time; it took two years but that’s okay. She’s eating great food, is happy as a clam, and her ejection fraction is now 50 percent. She’s in a mild heart failure category (65 being normal). She has regained her life.

Case study 2:

This is a gentleman who was affected by heart failure with an ejection fraction of 25 percent. His story also included a weight loss surgery – a sleeve gastrectomy in 2013. Like most people who don’t learn how to eat and change their lifestyle after weight loss surgery, they regain weight if no one ever teaches them about healthy eating. He found me and went from 340 pounds down to 250 pounds. His ejection fraction now is up to 42 percent, which is still mild heart failure, but he’s regained his life. He’s consulting and back at work. It’s just so transformative. Heart failure is not typically reversed. It’s one of those chronic things where doctors just don’t see it getting better. You might go to the doctor and they say, “Diabetes? You’re going to have it forever,” and that’s not true – you can reverse diabetes and obesity, and some cases of heart failure can be reversed or greatly improved, too.

Case study 3:

You might say that it was really the weight loss that helped the first two individuals, but as I was thinking about it, this is a patient of mine who is in her mid-70s and her heart failure has gotten to be normal. Her ejection fraction went from 35 to 55 and she really hasn’t lost much weight. She had a coronary blockage, meaning the conduction system was shot, so she had a pacemaker put in. Over the years that I’ve known her she basically has had normal heart function. She’s kind of stuck at 190 lbs; she’s got trouble with still eating carbs. She’s a carb addict but has limited the carbs a lot. I don’t know that she’s in ketosis all the time but this makes me think that it’s not just the weight loss that’s helping the heart here, maybe it’s the ketones.

The rationale

How do we explain these amazing cases? It turns out that the heart muscle is fueled by fat and ketones. If you have a pump and it is going all the time, you want the best form of energy delivered there and the highest concentration of energy per gram. That is fat. The heart muscle runs on fat. A normal heart is about 86 percent percent fat, free fatty acids, and then 6.4 percent ketones. Sugar is not a contributor to fuel the heart muscle. When someone has heart failure, the ketone use goes up a little bit – from 6 to 16 percent, but it’s still 70 percent fat fueling the heart. The abstract of a paper published in 2020 says, “The heart primarily consumed fatty acids and, unexpectedly, little glucose.” It wasn’t unexpected to the heart! The heart always ran on fuel from fat. It was the study authors and the cardiologists that were surprised, not the heart! This is using modern methods and state-of-the-art equipment. The heart runs on fat. You have to realize we’re talking about the heart muscle itself, not the coronary arteries, not the electrical conduction system. It gave me a lot of glee to present to doctors that actually it is fine if they use a keto diet for heart failure. I’m not talking about the coronary arteries, I’m not talking about the conduction system, I’m talking about the muscle itself.

Heart failure research: The old paradigm

What we came through was a paradigm of “glucose fixes everything.” The low-fat diet for heart disease era got things so distorted. It was thought that the heart needed more glucose even though it ran on fat. Studies were conducted to infuse glucose and insulin during heart attacks. The studies were negative, meaning it didn’t work. The infusion of glucose and insulin during heart failure did not lead to improved outcomes. There is still, however, a “cognitive dissonance” – the reality is, you want the heart to have fat but you’re telling people not to eat fat. The main worry is that fat itself would go out in the arteries of the heart and “clog” the arteries. That’s not what happens but it’s still logical. I was in that world for a long time just blindly looking at this but I’m thinking that that increase in ketones is a good thing when the heart is actually asking for more ketones and fat.

There’s a new drug class that has been studied pretty well that makes the urine leak sugar, called SGLT2 inhibitors, and they reduce heart failure readmission rates. It has a consequence, called “normoglycemic ketoacidosis.” (This means ketoacidosis even when blood sugar is normal.) The only time I’ve seen ketoacidosis in my patients on a keto diet is when they’re on these drugs. I never saw ketoacidosis until these drugs came about. They can cause ketoacidosis whether you’re on a keto diet or not. I don’t want you to be taking SGLT2 inhibitors. Most cardiologists are handing it out now to people with heart failure. It has been studied, but it has this negative consequence of infections in the urine and then ketoacidosis. There is a paper that suggests maybe the mechanism that these drugs help with heart failure is ketosis. The heart needs ketones. Then I’m thinking, well, why not just do a keto diet without a drug and you get the ketones from your own body fat?!

The keto diet

The keto diet provides fatty acids and ketones from your own body, or, if you’re at your ideal weight, then you’re just consuming protein and fat, and you’re going to be burning the fat, providing ketones from the fat that you’re eating. The cardiac muscle may be fueled by fatty acids and ketones, but what about the atherosclerosis that causes coronary artery disease (the narrowing and the blockage)? Metabolic syndrome – also known as insulin resistance – is now implicated as the major risk factor for atherosclerosis and which leads to the coronary artery disease and blockage. Metabolic syndrome is also a major risk factor for heart failure, which is the muscle itself failing whether you have arterial blockage or not. The keto diet reduces the cardiometabolic risk by reducing metabolic syndrome.

What about the conduction system and the keto diet? Arrhythmias can be benign/harmless or be serious palpitations. Some people have it early on during the keto adaptation phase because of fluid shifts. I don’t worry about those if they go away. There was a study that showed atrial fibrillation associated with lower carbohydrate intake and it got big news but the lowest quartile of the people in this study were were eating 37 percent carbohydrate, so it really wasn’t addressing a diet like a keto diet that only has five to ten percent carbohydrates. It was really apples and oranges; the study didn’t apply to a carb intake as low as on a keto diet. I see gout, kidney stones, or atrial fibrillation occasionally in people losing weight on a keto diet, but then I also see them in people not on a keto diet. I don’t know if the relative frequency of these things is any different than any other way of eating. It actually may not be related to the diet at all. If you get in a car accident on a keto diet, it probably wasn’t the diet that caused it! I don’t fall victim to that anymore; I want a comparative study to know the relative frequency of these things.

To sum it up, the cardiac muscle is fueled by fatty acids and ketones during normal conditions and heart failure/coronary disease is caused by metabolic syndrome which a keto diet can reverse. Based on this physiology there should be no concern about using nutritional ketosis to treat heart failure. A well-formulated keto diet (different from “internet keto”) will also lead to weight loss which may improve heart failure independently of nutritional ketosis. The keto diet reduces cardiometabolic stress by addressing the metabolic syndrome (triglycerides, HDL, waist circumference, glucose level, and blood pressure elevation that may not be to the level of hypertension or diabetes).

I presented three cases of an improvement of heart failure while following a well-formulated keto diet. Clinical monitoring is essential during such a program through someone who understands how to manage heart failure and de-prescribe medicines. Of course, we can’t say that the keto diet itself leads to these improvements, but I really haven’t seen anyone else come and ante-ing up the cases like this of their programs; this is not commonly presented in our obesity medicine conferences. A review of the fuel use of the heart and underlying causes of coronary disease is reassuring that this approach may be safe. We strongly urge cardiologists to consider the keto diet and their clinical and research efforts for heart failure. Steve Phinney and Jeff Volek are now funded to study heart failure by the Department of Defense in the U.S., which is fantastic. I think it’s going to be looking at drinking ketones versus the keto diet on its own. It might turn out not to work, but you have to do it to find out.

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