How Ozempic Impacts Your Heart

Ozempic does not only decrease body weight, but also muscle mass. Your heart is a muscle.

With each passing day, the use of GLP-1 agonists like Ozempic (generic: semaglutide) becomes more ubiquitous. This drug has become one of the most profitable drugs of this post-covid medical era, as it is an incredibly potent “weight-loss” drug.

For those unaware of my position on Ozempic and drugs like it, you can read here:

Ozempic: Miracle Drug or Ticking Time-Bomb?

I understand why doctors and patients alike support the use of drugs like Ozempic. At the end of the day it boils down to “weight loss.”

Obesity is rampant, and people are under the impression that if you just reduce your weight, then you will be healthy. To some extent, this is true. In other ways, it’s not. In many cases, you can argue that obesity co-varies with other markers of disease. For example, when you are fat, you also tend to be diabetic.

When you stop eating (because of drugs like Ozempic), you also stop eating the stuff contributing to your insulin resistance, whilst also losing weight by lower caloric intake.

But, many overlook an important assumption.

The assumption is that obesity is the cause of their disease, rather than another effect of their underlying problem.

In fact, there are some (myself included), who believe that the fat you put on is actually a mechanism designed to protect you against the very things which cause disease in the first place.

If you think about it, your body wouldn’t simply put on fat to weigh itself down or drown itself with insurmountable mass. To some extent, it has a purpose. In other ways, obesity is the effect of underlying disease.

Ozempic and the Heart

Recently, I stumbled upon an article that I thought may be worth your attention.

A group of researchers from the University of Alberta published some experiments they performed on mice, and measured changes to their hearts (amongst other things).

In part, this experiment was conducted to look where others haven’t.

Although drugs like Ozempic have been around for decades (used for diabetes), they have not received widespread attention until recently. Now that Big Pharma has found another blockbuster drug (accomplished by just changing the indication, rather than creating a new drug), we have to be extra careful.

It is exactly in moments like these, during widespread excitement and new revenue streams, is when the art of medicine has to make way for “The Science.”

For now, The Science has decided that Ozempic is the next best thing since Insulin. The Science has also put drugs like Ozempic (GLP-1As) into management algorithms. A push that will make many people happy.

• Pharma makes profits, because insurance will cover it

• Doctors look great, because they can “fix” the ultimate lifestyle disease with a pill

• Patients are happy, because they lose weight

That’s all to say that, at this very moment in the history of Ozempic, we have to be extra careful and vigilant about what we are told to believe.

Tread lightly.

Martens et al published this article on October 16th in the translational edition of the Journal of the American College of Cardiology.

Many people now report that people who take Ozempic do not only lose fat, but also lean muscle mass. Or in medical terms, they lose skeletal muscle.

Skeletal muscle is not the only type of muscle in the body. There is also smooth muscle, and heart muscle (or cardiomyocytes).

Since we have observed skeletal muscle loss, the authors wanted to see what effects (if any) Ozempic has on heart muscle.

To test this, they took two cohorts of mice. One cohort was fed a diet designed to gain weight, and the other was kept lean. The diet was specifically chosen to avoid diabetes, cardiac hypertrophy (overgrowth) or dysfunction. In hopes that this would more closely resemble people who would take Ozempic just for weight loss.

They evaluated the hearts of these mice before randomization, to make sure there were no pre-existing differences between their hearts.

Then, the mice were given Ozempic for 21 days.

As expected, the mice that were obese lost body mass and fat.

What was surprising, is that the obese mice also lost weight/size of their heart.

Here, LV means left ventricle.

Also, the cardiomyocytes (the cells of the heart) got smaller:

What about the lean mice? Good question.

Interestingly, although their overall body weight did not decrease, they did lose lean muscle mass.

The lean mice also lost heart muscle mass:

It gets even weirder.

To see if there was something else going on with the rest of the body that may be impacting the size of the heart, the authors took cultured heart cells and essentially bathed them in Ozempic.

Guess what? The heart cells in the petri dish also got smaller.

Before we get to what I think is going on here, we must first discuss the other things which the authors reported about the heart.

The most important thing to note is that apart from the dimensions of the heart, they also report heart function parameters like ejection fraction and velocity across heart valves.

These metrics turned out to be normal in these mice. But, I think this does the reader a disservice. In part, I think many people will read this and think

“Ok, that’s weird. But their hearts are functioning normally.”

Right?

Not exactly. Let’s take ejection fraction as an example.

Ejection fraction is essentially a measure of how much blood your heart pumps out relative to how much blood goes into it. A “normal” ejection fraction (EF) is over 50-60% depending on who you ask.

There are two important problems in using EF to make ourselves feel better about these strange results.

First of all, there is such a thing as heart failure with preserved ejection fraction. Which means that even if your EF is normal, you can still have heart failure.

Secondly, EF is an inappropriate metric to use in this specific context because of what the authors observe about the heart’s dimensions.

The authors report that the heart muscles are decreasing in size, the weight of the heart is reduced, and so is the size of the left ventricle (a chamber of the heart).

If your heart is getting smaller, it does not mean that it is getting less efficient at pumping blood (which is what is conveyed by EF).

Simply, a smaller heart takes in less blood volume…and so there is less blood to pump out. On the surface, the EF looks normal. But, that doesn’t mean that the heart is okay.

It’s still shrinking!