It's virtually impossible to eat a healthy diet unless you (1) cook most of what you eat (2) from whole foods. That's because both restaurants and processed food manufacturers take the cheap and easy way out by larding up their offerings with fat, salt, and sugar. It's more expensive to eat healthy, and it takes a lot more effort. It's lazy to fob this problem off on
the people of Walmart, and calls for more personal responsibility are no help. The relative lack of healthy options places a disproportionate burden on the poor, who often live in "food deserts" where
it's extremely difficult to buy fresh, affordable food.
While it surely would help if Americans lost weight, people in other developed countries smoke and drink a lot more than we do, and their health care costs are still about half of ours, even though they see their doctors more often than we do. The main reason we pay a lot more for health care than everyone else in the developed world is that the prices our health care providers charge are a lot higher than they are in other developed countries. For everything from ambulance rides to hip replacements to prescription drugs to (especially) hospital stays, we just pay a lot more than everyone else. And we get nothing for it. Instead of blaming the poor stupid schlubs riding around in carts at Walmart, we ought to blame our private, for-profit health care system that allocates wealth and income away from ordinary people to the well-to-do who work in gleaming office towers and always-under-construction hospitals.
An anecdote: Some time ago I read a piece by Atul Gawande that focused on the efforts of a small group of doctors working at a large hospital. They determined that a hugely disproportionate share of the hospital's billings went to a small percentage of the hospital's patients, who mostly suffered from chronic conditions. The doctors located these patients and arranged for the hospital to send someone out to see them on a regular basis. They'd ask the patients how they were doing, check on their meds, see if they needed anything. The billings to this group of patients fell off sharply, even after accounting for the cost of the home visits, because as a result of the increased attention they were much less likely to require hospitalization.
This great result was a big problem from the hospital's perspective. It realized that it was effectively paying its doctors to reduce its revenues. Instead of expanding the program that made more people better off for less money, the hospital killed it. The hospital administrators didn't do this because they were evil. They did this because they were rational. They responded exactly how you would expect profit-maximizers to respond -- indeed, how the hospital's shareholders would presumably demand that they respond.
You don't fix problems like these by blaming the schlubs and demanding that they have more "skin in the game." (Again, Americans already have more "skin in the game" than people in other developed countries, where utilization is higher and prices are lower.) You fix problems like these by ditching the dysfunctional system that persistently produces such lousy outcomes.