I'd dig one deeper and look at the reasons why it's "not feasible" and the change that first. If people propose "national emergency" as a solution, clearly such options should be on the table.
It's not feasible for various reasons, but they mostly boil down to "political will". There's two main causes I see: food/nutrition, and lifestyle (i.e. not enough exercise, and using cars, which is caused by urban design). There simply isn't enough political will to make any significant change on either of these fronts. Don't forget, the US is almost certainly going to elect Trump for a 2nd term, so obviously there isn't going to be any positive change in either nutrition or urban design for quite some time.
So, basically the US electorate chooses to be obese? If so, the underlying question is: why do they choose this?
I can think of several reasons, but to me the most obvious cause is "runaway capitalism", where a few big corporations lobby and market and (mis)inform, to make people think this is what they want, just so they can sell more cars, sugar, processed (high marging) foods and so on.
Not to make this an anti-capitalist rant, to be clear. Just that I'm fairly sure we're seeing a clear limitation of "free markets", where people simply aren't the rational homo-economicus that many promised we'd be.
There's tons of healthy food options available to consumers these days, even in regular supermarkets. They all have "organic" food aisles now. Some Americans have become more conscious of this and have adjusted their diets. (Of course, there's also some companies trying to profit off this unfairly, like advertising "gluten free" on foods that would never contain gluten anyway, and also pushing gluten-free foods as "healthier" when there's really no evidence for that, they're healthier of course for people with a gluten allergy or sensitivity but that doesn't extend to everyone.)
In a democratic society, it's the people's responsibility to be educated about issues, so they can vote accordingly. Most Americans are making conscious choices to eat bad foods, not exercise, live in suburbs with car-dependent lifestyles, etc. They could move to inner cities and/or push locally for more density and anti-car measures, but they don't, outside of a few select places.
Instead, a large chunk of American society "educates" itself about conspiracy theories and the "importance" of guns and religion, and votes accordingly, and what you get is the society you see now.
I'd dig one deeper and look at the reasons why it's "not feasible" and the change that first. If people propose "national emergency" as a solution, clearly such options should be on the table.