Heart Disease in Women: It's Not Your Cholesterol, It's Your Insulin
A study published this month in JACC, the flagship journal of the American College of Cardiology, followed over 117,000 women for years and found something worth paying attention to. Women who did at least two hours of strength training a week had a 20 percent lower risk of major cardiovascular disease and a 44 percent lower risk of heart attack compared to women who did none. Add in regular aerobic activity and the heart attack risk dropped by 45 percent.
It is a good study and it deserves attention. But before this turns into another headline about a magic amount of exercise, I want to be clear about what is actually driving that result. It is not the lifting by itself. It is what lifting does to how your body handles insulin, and food is doing the larger share of that work every single day, all day, whether or not you make it to the gym.
So why does muscle protect the heart at all? The honest answer has very little to do with calories burned. It has to do with insulin, and insulin is shaped far more by what is on your plate than by what happens in a weight room two hours a week.
The cholesterol story has a hole in it
For years the message was simple. High cholesterol clogs arteries. Lower your cholesterol and you lower your risk. Cut saturated fat, take a statin if needed, and you are doing the responsible thing.
Dr. Robert Lustig, professor of pediatrics at the University of California, San Francisco, has spent years pushing back on this. In a piece he co-wrote for The Pharmaceutical Journal with Maryanne Demasi and Aseem Malhotra, he argued that aggressive lowering of LDL cholesterol has been the cornerstone of preventive cardiology for decades, even though the evidence behind that approach is weaker than most people realize. His position is direct. The cholesterol hypothesis and the calorie hypothesis are both outdated, and insulin resistance is the factor that actually predicts cardiovascular risk and type 2 diabetes.
Lustig has also pointed out that insulin resistance does not show up the same way in every part of the body. It shows up as type 2 diabetes when it hits the liver. It shows up as PCOS when it hits the ovaries. And when it hits your heart, it shows up as cardiovascular disease. Same root problem, different symptom depending on which organ is struggling to respond to insulin.
Dr. Malcolm Kendrick, a GP who spent years working with the European Society of Cardiology, has made a similar argument from a different angle. After decades of studying what actually drives heart disease, he has written that cardiovascular risk correlates more strongly with markers of whole body insulin resistance than with almost anything else he has studied, glucose included. In his view, insulin resistance triggers inflammation, raises blood clotting factors, and sets off the chain of events that ends in a heart attack. Cholesterol gets blamed for damage that insulin resistance caused.
This does not mean cholesterol is irrelevant. It means it is not the starting point. Insulin resistance is.
What insulin resistance actually does to your heart
When your cells stop responding properly to insulin, your pancreas compensates by pumping out more of it. That extra insulin does not stay quiet in the background. It raises blood pressure. It raises triglycerides. It lowers HDL. It increases inflammatory markers like C-reactive protein. It thickens blood and makes clotting more likely.
Here is where cholesterol gets dragged into a problem it did not start. Chronically high insulin raises blood pressure, and high blood pressure pounds away at the inside lining of your arteries, the endothelium. That constant pressure causes small tears and damage in the artery wall. Your body needs to repair that damage, and cholesterol is one of the materials it sends to the site to patch things up. Cholesterol shows up at the scene because there is damage to fix, not because cholesterol caused the damage in the first place.
Over years of repeated damage and repair, those patches build up into plaque. Doctors look at an artery full of plaque, see cholesterol sitting right there, and conclude cholesterol is the villain. It is closer to a repair crew getting blamed for a building falling down because their trucks were parked outside it. The real story is the pressure and inflammation that kept tearing the artery wall in the first place, and that traces back to insulin.
Every one of those changes is a known contributor to heart attack and stroke. None of them require high cholesterol to happen. They happen because of chronically high insulin, full stop.
This is also why insulin resistance hits women particularly hard during the years around menopause. Estrogen decline makes cells more resistant to insulin at the exact same time visceral fat tends to increase. That combination raises cardiovascular risk in a way that has nothing to do with what a woman eats for fat or cholesterol that week, and everything to do with what is happening to her blood sugar and insulin levels day after day.
Food sets the insulin load, lifting just helps clear it
Insulin is high or low mostly because of what you eat. Sugar and refined carbohydrate hit your bloodstream fast and hard, and your pancreas answers with insulin. Eat that way meal after meal, year after year, and your cells stop responding the way they should, so your pancreas pumps out even more insulin to get the same result. That cycle is the actual disease process. It starts on your plate, long before it shows up as a number on a lab report.
This is why diet has to be the starting point. Lower the carbohydrate load and there is simply less glucose asking for insulin's help in the first place. No amount of exercise changes how much sugar and starch you ate at dinner. Food determines how much work insulin has to do. Everything else is downstream of that.
Muscle plays a real but smaller role. Muscle is the largest site in your body for glucose disposal. When you lift weights, your muscles need fuel, and they pull glucose out of your bloodstream to get it. Resistance training increases the number of glucose transporters in muscle tissue and makes existing transporters work harder. Over time, more muscle mass means more total capacity to clear glucose from your blood without needing as much insulin to do it.
That is a completely different mechanism from "exercise burns calories." Strength training is not primarily working through the scale. It is working through your muscle's ability to absorb glucose, which lowers the chronic insulin load your body is carrying.
But muscle can only do so much if the diet keeps flooding the bloodstream with more glucose than even a strong, well trained muscle can absorb. Two hours of lifting a week paired with a diet that keeps spiking your blood sugar is still asking your pancreas to overproduce insulin the other one hundred sixty six hours of the week. Lifting helps clear what is already there. It cannot stop more from arriving if the diet keeps producing it.
Kendrick has been saying this for years in plain terms. If chronically high insulin is a major driver of heart disease, the fix is lowering insulin, and that starts with a low carb diet. Resistance training is a useful addition on top of that, not a replacement for it.
The JACC study only tracked exercise habits. It did not measure what these women ate, so it cannot tell us how much further their risk would have dropped with a lower carbohydrate diet added on top of the lifting. What it tells us is that muscle matters independently of cardio. It does not tell us that lifting alone, without addressing food, is enough to fully correct insulin resistance.
What this means for you
You do not need to wait for your doctor to bring up insulin resistance at your next physical, because most still will not. You can start addressing the actual mechanism right now, and the order matters.
Diet comes first. Lower the carbohydrate load on your body through food. Less sugar, less refined starch, more protein and animal fat, and your insulin has less work to do all day, every day. This is the input you have the most control over, and it is the one driving how much glucose shows up in your blood in the first place.
Strength training adds a second layer on top of that. Two hours a week was the threshold in the study, and that is not an extreme commitment. It is two or three sessions of lifting something heavier than you are used to. But lifting is support, not a substitute. Two hours of weights cannot outwork a diet that keeps insulin elevated the other one hundred sixty six hours of the week.
Stop treating your cholesterol number as the whole story. It is one data point. Insulin resistance is the deeper one, and it is the one nobody is screening for at your annual checkup unless you ask.
I have spent years now eating this way and lifting heavy, and the women I hear from say the same thing. Energy improves first. Strength comes next. The blood work changes after that. The order is not random. Fix the insulin problem and the rest tends to follow.
FAQ
Does this mean cholesterol does not matter at all for heart disease? No. It means cholesterol is not the starting point most people were told it was. Insulin resistance drives many of the changes, like inflammation and high triglycerides, that get blamed on cholesterol alone.
How much strength training do I actually need? The study found benefits starting at one hour a week, with the strongest protection at two or more hours weekly. Two to three sessions of resistance training a week is a reasonable target for most women.
Can diet alone fix insulin resistance without exercise? Diet does most of the heavy lifting by lowering how much insulin your body needs to produce. Resistance training adds a second pathway by giving your muscles more capacity to clear glucose without insulin doing all the work. Together they work better than either alone.
Is this only relevant after menopause? Insulin resistance can develop at any age, but the hormonal shifts around perimenopause and menopause make it more common and harder to ignore. Starting earlier gives you more room to prevent it rather than reverse it.
References
American College of Cardiology. Strength Training Linked to Lower Heart Disease Risk in Women. June 2026.
Zhang T, et al. Resistance Training, Aerobic Activity, and Cardiovascular Disease Risk in Women. Journal of the American College of Cardiology, June 2026.
Demasi M, Lustig RH, Malhotra A. The cholesterol and calorie hypotheses are both dead, it is time to focus on the real culprit: insulin resistance. The Pharmaceutical Journal.
Kendrick M. What Causes Heart Disease (series). drmalcolmkendrick.org.
Frontiers in Endocrinology. Effect of nine different exercise interventions on insulin sensitivity in diabetic patients: a systematic review and meta-analysis. 2025.
Circulation Research. Unraveling Skeletal Muscle Insulin Resistance: Molecular Mechanisms and the Restorative Role of Exercise.
This article is for educational purposes only and is not a substitute for personalized medical advice. Talk to your doctor before making changes to your diet, exercise routine, or medications, especially if you have an existing heart condition
