If you're one of the evidently healthy people who has decided that 50 is the new 40, here's a dose of sobering news. The big decline in deaths due to heart disease that the U.S. has enjoyed over much of the past century has slowed to a crawl. And for one age group — middle-aged Americans — deaths due to cardiovascular disease are actually on the rise.

The death rate in the U.S. due to cardiovascular disease, including heart disease and strokes, had dropped more than 70% over six decades — until 2011. Since then, however, deaths due to cardiovascular disease have dropped by a mere 4 percent, according to the U.S. Centers for Disease Control and Prevention.

Heart disease has been the nation's top killer, but public health experts had expected it to be supplanted by cancer by 2020. Yet with these latest numbers, expect heart disease to remain Public Enemy No. 1 for a while.

Why are heart attacks and strokes holding strong? America doesn't smoke as much anymore; the days of cigarette butt-filled ashtrays on work desks and restaurants clouded in an ashen haze are long gone. We tell ourselves we're eating better — gluten is a dirty word for many people, and the meat-free Impossible Burger now appears prominently on menus at Burger King, Red Robin and White Castle. We're living healthier, right?

Cardiologists instead point to two enduring culprits, The Wall Street Journal reports: obesity and the rise in Type 2 diabetes. Both contribute to high blood pressure, America's "silent killer" that ramps up the risk of strokes and heart problems. According to the Journal, nearly 40% of American adults over 20 are obese, and 9.4% of U.S. adults 18 and older suffer from diabetes. Those percentages should startle and humble all of us.

Insufficient exercise, bad food, and too much of it. Yes, this trifecta takes a toll, and the population segment bearing much of the brunt is those middle-aged Americans: The CDC says the heart disease death rate for people between 45 and 64 rose 1.5% from 2011 to 2017.

Chuck the old image of a heart attack waiting to happen — an older man, usually a smoker, with cholesterol levels out the roof. Increasingly, heart disease patients are younger, more obese, often women, and less likely to smoke.

Heart disease kills 859,000 Americans every year, the CDC says, roughly one-third of all deaths. Treating heart disease represents a $199 billion annual hit on the country's health care system, and $131 billion in lost productivity due to premature deaths. But take heart (sorry, we couldn't resist): The World Health Organization says 80% of premature heart attacks and strokes are preventable.

Easy fixes won't suffice. At best the supplements route has its limits, and many of those pills do nothing but shrink your bank account. We hate to sound like a broken record, but simply stopping smoking isn't enough anymore. Sensible diet? Check. More exercise? Check. Regular doctor visits? Check. Taking the statins or other meds the doc prescribed for you? Check.

You don't need to hop on the bandwagon of every new health fad that gets a headline. All you need is a bit of common sense — and the willpower to act on it.