One of the most disheartening aspects of my sixty-year career in cardiology has been witnessing a steady decline in the rate of heart disease in America, only to have victory snatched by the jaws of defeat. Yes, heart disease affects one in four Americans, and for almost a century now it has remained the leading cause of death in the United States. But in the mid-1970s, after a sixty-year gradual increase as the U.S. population aged, there was a significant downtick in the frequency of cardiovascular heart disease and related stroke mortality rates.
By 2000, mortality rates from heart disease had declined to about one-third their 1960s baseline. From 2006 to 2016, the annual death rate attributable to coronary heart disease declined by 31.8 percent, and the actual number of deaths declined 14.6 percent.
That remarkable progress in battling the leading killer of Americans was fueled by both improved treatment and prevention. The huge and costly public information campaigns about the dangers of cigarette smoking and about lowering cholesterol through a change to a more healthful diet, the widespread use of statin and other medications to lower cholesterol, and improvements in preventing and treating hypertension were paying off. Again, the war against heart disease was by no means over, but after four decades of lowering its rate, heart disease seemed to be on the run, and the day when it was no longer the leading cause of death in America was actually in sight.
Then came the bad news in May 2019. In an article published in the Journal of the American College of Cardiology, a comprehensive study conducted by Northwestern University, found death rates due to heart failure were now increasing and, even worse, actually had been increasing since 2012.
The study used data from the National Health and Nutrition Examination Survey, a program of studies conducted by the Centers for Disease Control and Prevention (CDC) designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations and provides a snapshot of the overall health of the nation. In short, the data and its conclusions were definitive.
As lead researcher Dr. Sadiya Khan, assistant professor of medicine at Northwestern University’s Feinberg School of Medicine and a Northwestern cardiologist, noted in the published article, the rise in deaths came despite significant advances in medical and surgical treatments for heart failure in the past decade. The cause of this discouraging reversal in what had been steady progress for more than forty years? In a word, obesity, or to be more precise, the nation’s current obesity epidemic.
I don’t use the word “epidemic” lightly, but there is no other way to describe the dramatic increase in rates of obesity in the United States, which, as it turns out, have paralleled an increased rate of heart failure. According to the latest statistics from the CDC, 39.6 percent of adults and 18.5 percent of children ages two to nineteen are obese in America. Let’s pause for a moment and reflect on those numbers. If you were to walk into any public venue in the United States today—a bank, a restaurant, a house of worship, an airport—on average four out of ten adults there would be clinically obese, and nearly one out of five children would qualify as obese as well. Those are chilling statistics.
To be perfectly honest, it’s not like my colleagues in cardiology didn’t notice that patients were, well, getting larger—much larger—over the last twenty years. In fact, the origins of the obesity epidemic can be traced all the way back to 1962, when the first uptick in obesity rates were documented; since then, the obesity rate has increased steadily.
“The success of the last three decades in improving heart disease death rates is now being reversed, and it is likely due to the obesity and diabetes epidemics,” said Khan. “We focused on patients with heart failure because they have the highest mortality related to cardiovascular death. They have a prognosis similar to metastatic lung cancer.”
In other words, while the study doesn’t document it, it’s likely that other kinds of coronary heart conditions like silent heart disease have also increased.
An estimated 6 million adults in the United States have heart failure. What exactly is meant by heart failure? Simply put, heart failure is when the heart muscle doesn’t function properly in its squeezing and/or relaxing functions. This causes symptoms like shortness of breath and swelling. When the heart can’t adequately squeeze to pump blood, it’s called “heart failure with usually reduced ejection fraction”; when the heart can’t relax, it is called “heart failure with preserved ejection fraction.” About 50 percent of individuals diagnosed with heart failure (of either kind) will die within the next five years.
“Given the aging population and the obesity and diabetes epidemics, which are major risk factors for heart failure, it is likely that this trend will continue to worsen,” said Khan.
Recent data show that the average life expectancy in the United States is also declining, which underscores Khan’s contention that cardiovascular death related to heart failure may be a significant contributor to this change.
So, if the obesity is, pardon the pun, at the heart of the increase in fatal coronary heart disease, what caused the obesity epidemic? That is the $64 billion question, which is the estimated annual cost to the U.S. economy in lost productivity because of the obesity epidemic. Then you can add another whopping $147 billion in medical costs related to obesity treatment.
The challenge in the treatment and prevention of obesity is that it’s a complex health issue to address. Obesity results from a combination of causes and contributing factors, including diet (notably, the widespread availability and popularity of fast and processed foods over the last five decades), a sedentary lifestyle, and individual behaviors. There’s even a genetic component, although the last third of the twentieth century was the first in the history of humans in which obesity became a widespread phenomenon, so it’s likely that “nurture” rather than “nature” is more important in the rise of obesity. It’s the perfect storm of medical conditions.
However, some well-respected medical researchers believe that, all things considered, something else beyond an increase in sedentary lifestyle and fast foods may be the primary culprit—something far more sinister. In a fascinating book, The Obesogen Effect, Dr. Bruce Blumberg, PhD, posits that the obesity epidemic is not the result of too many cheeseburgers or not enough exercise. Rather, Americans’ growing waistlines are due to chemical agents found in an array of household goods, from food containers to cleaning and personal care products, which disrupt our hormonal systems. Even worse, his research shows that the effects of these “obesogens” can interfere with the expression of our genes and thereby get passed on from generation to generation.
It was previously thought that while being overweight might prevent you from achieving maximum health, it was relatively unimportant as a risk factor in coronary heart disease. Now we realize that obesity in and of itself is a major risk factor. In fact, obesity alone affects heart health in a multitude of ways, including by actually changing the structure of the heart.
In a groundbreaking study published in 2019 in the European Heart Journal, researchers for the first time found evidence that excess weight and body fat cause a range of heart and blood vessel diseases, rather than just being associated with them. In particular, the study showed that as body mass index (BMI) and fat mass increase, so does the risk of aortic valve stenosis, a condition in which the heart valve controlling the flow of blood from the heart to the body’s largest blood vessel, the aorta, narrows and fails to open fully. Blood can back up in other parts of the heart and sometimes the lungs. This can lead to shortness of breath, tiredness, fainting, chest pain, and an irregular heartbeat. While the greatest danger was for aortic valve stenosis (46 percent increased risk), the study found those who were clinically obese were also at a high risk for ischemic stroke, transient ischemic attack, atrial fibrillation, heart failure, and peripheral artery disease.
This was the first heart disease study to use a fascinating new research technique called Mendelian randomization. This technique uses genetic variants that are already known to be associated with potential risk factors, such as BMI and body fat, as indirect indicators of, or “proxies” for, these risk factors. This enables researchers to discover whether the risk factor is the cause of the disease (rather than the other way around) and reduces bias in results because genetic variants are determined at conception and cannot be affected by subsequent external or environmental factors or by the development of disease.
The researchers, led by Susanna Larsson, associate professor and senior researcher at the Karolinska Institute, Stockholm, Sweden, studied ninety-six genetic variants associated with BMI and body fat mass to estimate their effect on fourteen cardiovascular diseases in 367,703 participants of white British descent in UK Biobank, a UK-based national and international resource containing data on five hundred thousand people, aged forty to sixty-nine years. Larsson said, “The causal association between BMI and fat mass and several heart and blood vessel diseases, in particular aortic valve stenosis, was unknown. We found that higher BMI and fat mass are associated with an increased risk of aortic valve stenosis and most other cardiovascular diseases, suggesting that excess body fat is a cause of cardiovascular disease.”
There are other ways that obesity physically changes the heart. Being overweight can lead to a buildup of fatty material in the arteries (the blood vessels that carry blood to your organs). If the arteries that carry blood to your heart get damaged and clogged, it can lead to a heart attack. Also, the heavier you are, the more blood you have flowing through your body. The heart has to work harder to pump the extra blood. It stretches, getting bigger and thicker, and the thicker the heart muscle gets, the harder it becomes for it to squeeze and relax with each heartbeat. Gradually, the heart may not be able to keep up with the extra load. You may then have congestive heart failure.
People who have a substance abuse problem oftentimes have what addiction medicine describes as a “co-occurring disorder,” or another condition that parallels and contributes to addiction. For example, a person might be addicted to opioid drugs but simultaneously suffer from depression, anxiety, or attention deficit hyperactivity disorder—all common co-occurring disorders of alcohol and drug addiction (which we’ll learn more about in the next chapter).
In a sense, obesity has co-occurring disorders, notably high cholesterol, hypertension, and diabetes. As we learned earlier, each of these alone is a risk factor for silent heart disease, but it now appears obesity heightens the risk further.
For example, obese individuals also have a much greater chance of developing diabetes. According to the American Heart Association, at least 68 percent of people aged sixty-five or older with diabetes also have heart disease. Also, obesity can increase the levels of low-density lipoprotein (LDL) cholesterol and triglyceride levels, but it can also lower the good high-density lipoprotein (HDL) cholesterol (which is important in controlling LDL cholesterol). And, finally, as noted earlier, there’s a strong correlation between high blood pressure and obesity.
People with severe obesity have a risk of developing heart failure almost four times higher than that of people with an ideal body weight, or the optimal body weight associated with maximum life expectancy (usually as determined by body mass index). Studies also show that the link between obesity and heart failure persists even after accounting for other risk factors. To be clear, if you are obese, you’re still at increased risk for heart failure even if you don’t have high blood pressure, high cholesterol, or diabetes. As is the case with hypertension or a sedentary lifestyle, this lack of symptoms can make obesity dangerous as a risk factor for silent heart disease.
There’s still another way obesity increases the risk of heart disease. Obesity contributes to systemic inflammation, which long has been known to have a correlation to heart disease, measured by multiple techniques, including the C-reactive protein blood test.
How exactly does that work? We’re not sure yet, but one grand theory—yet to be proven—posits that inflammation in the body is at the roots of many if not most diseases. What we do know today is that an obese person tends to have a disproportionately high volume of a certain kind of adipose tissue called visceral fat. In fact, visceral fat obesity is present in almost 90 percent of obese patients with ischemic heart disease.
Until recently, it was thought that all fat was created equal—a kind of benign tissue that just sat there. Sure, the sheer added weight of excessive fat tissue strained everything in the body, from the heart muscle to knee joints, but its damage seemed to stop there. That is, being forty pounds overweight was like being a normal weight but walking around with a forty-pound weight in your backpack.
However, beginning in the late 1980s and early 1990s, powerful new imaging techniques greatly advanced the understanding of the health risks associated with body fat accumulation. Techniques such as computed tomography and magnetic resonance imaging revealed to medical scientists that there were not one but two different kinds of fat: subcutaneous fat, which sits just below the skin line and often accumulates around the hips, thighs, and buttocks of pear-shaped people, and a more insidious, intra-abdominal fat that surrounds the liver, heart, intestines, and stomach organs and is prominent in apple-shaped people.
Carrying excessive weight around your middle, also called central obesity, can make it harder for your body to use a hormone called insulin, which controls your blood glucose (sugar) levels. This can lead to type 2 diabetes. Having high levels of glucose in your bloodstream damages your arteries and increases your risk of heart and circulatory diseases.
Even worse, visceral fat, far from being benign, functions like a quasi-organ, and may actually produce pro-inflammatory cytokines and adipokines with cardio-depressant and pro-atherosclerotic properties. Visceral fat is typically associated with a westernized diet rich in saturated fats and sugars, which can further contribute to the pro-inflammatory state of patients, particularly since these macronutrients can activate pro-inflammatory pathways.
In the last chapter, we discussed how the body mass index wasn’t a particularly good measurement of sedentary lifestyle and, in fact, could mask sedentary behavior as a major risk factor. However, BMI combined with a waist circumference measurement (not necessarily the same as your pants waist size) are a good overall indicator of obesity. Learn how to measure your BMI and waist circumference by following the instructions available on numerous websites, including that of the National Institutes of Health (https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm). Generally speaking, the recommended waist measurements are below 37 inches (94 centimeters) for men and below 31.5 inches (80 centimeters) for women.
We’ll close this chapter by returning to the new data showing that obesity is a growing problem not only for adults but for children as well. We should all be concerned about a nation of overweight children and adolescents because soon they’ll become part of the problem. Obese children and adolescents are more likely to become obese adults with all the risk factors associated with cardiovascular disease (high blood pressure, high cholesterol, type 2 diabetes, and heart attacks).
Also, studies have documented the link between obesity and unhealthy or risky behaviors such as alcohol and tobacco use, premature sexual behavior, inappropriate dieting practices, and physical inactivity. Overweight children and adolescents may experience other health conditions associated with increased weight, including asthma, fatty liver disease, sleep apnea, and type 2 diabetes mellitus.
Finally, obesity puts children at long-term higher risk for chronic conditions such as stroke, musculoskeletal disorders, gallbladder disease, and breast, colon, and kidney cancers.