Proponents of "Medicare for All" often point towards European nations with universal healthcare systems to prove that single-payer could work here. The global ramifications of inevitably immolating our medical research and development aside, there's just one, massive elephant in the room that progressives love to ignore: obesity.

At 36.2 percent, the American obesity rate is the 12th-highest in the world and first among OECD countries. Of every European nation with universal healthcare, only the United Kingdom (27.8 percent) and Hungary (26.4 percent) come within 10 percent of the American obesity rate.

In Germany, France, Portugal, and Sweden, the national obesity rates are 22.3 percent, 21.6 percent, 20.8 percent, and 20.6 percent respectively. And in Denmark and Italy, fewer than 20 percent of people are obese.

Sen. Bernie Sanders, I-Vt., has also compared us to South Korea and Japan, two nations where fewer than 1 in 20 are obese.

In a private healthcare system, premiums account for individual health statuses, but within a voluntary risk pool, providers don't place many heavy demands on lifestyle choices. If you're paying for yourself, you have the right to live as you please. But the moment the public has a stake in your healthcare, it has a stake in your health.

It seems impossible for any real iteration of "Medicare for All" to succeed without massive amounts of regulation on lifestyle and health choices, or even effective obesity taxes. If the public owns the risk pool of "Medicare for All," then voters will surely demand to mitigate risk as much as possible.

The country under single-payer will make former Mayor Michael Bloomberg's soda taxes and food-nannying look like child's play. Everything from your sugar consumption to your alcohol would become a matter of public regulation, and the public would not only have the power but also the moral right to regulate how people live.

Of the 2.6 million deaths in the U.S. per year, 300,000 are caused by obesity. It's one of the single greatest drivers of avoidable healthcare spending, costing the country around $200 billion annually.

Progressives may call this fat-shaming. But it's really just public health and economics.