it is a very involved topic. but here is something from 2016 that speaks of it and is relevant to the HCFS/bad diet issue:

https://www.npr.org/sections/thesalt/2016/07/18/486051480/we...

[..]Americans are told to fill 50 percent of our plates with fruits and vegetables. But here's the contradiction, as the researchers see it: U.S. agriculture policies "focus on financing the production of corn, soybeans, wheat, rice, sorghum, dairy and livestock," the researchers write. About $170 billion was spent between 1995 and 2010 on these seven commodities and programs, according to the researchers.[..]

[..]"Higher consumption of calories from subsidized food commodities was associated with a greater probability of some cardiometabolic risks," the authors conclude. For instance, they found a higher probability of both obesity and unhealthy blood glucose levels (which raises the risk of Type 2 diabetes) among people who consumed the most calories from subsidized foods.[..]

having pasted the above, the article also takes the other side(because. NPR)..and i have points of disagreement with this bit:

[..]Consider this: Sugar hooked us on yogurt. Americans eschewed yogurt until Dannon began adding sugary jam to the bottom. Same story with cereal. Adding sugar to tasteless flakes drove up sales.

And then there's the idea that crop subsidies don't necessarily make food cheaper. Here are two reasons why. First, only a tiny slice — an estimated 15 percent — of the price we pay for processed foods, say, a box of cornflakes or cookies made with wheat and corn syrup, actually goes to the farmer.[..]

why? because all the excess production has to go somewhere. because school lunches and food bank supplies have certain guidelines. why is smuckers jam approved for school cafeterias? and the other grape jelly guy. i forget the name. because smuckers agrees to buy the excess HFCS.

HFCS also in peanut butter. the healthy vegetables and fruit isnt subsidised. only commodity crops. and only a small portion of it is for human food consumption. and it's only for commodities that is listed on the stock exchange. its the same with ketchup. ever wondered why we have HFCS in our tomato ketchup? and school cafeterias menu includes french fries and ketchup..both of which were considered to be part of the 'daily 5' vegetables/fruits for a balanced diet.

it is also the reason for our high meat consumption and why its cheap. subsidies doesnt pay farmers. it pays them to continue farming for feed, ethanol and HFCS. the good and healthy food we eat comes from canada or south america. because it's cheaper to pay subsidies than hand over something as important as feeding 330 million people.

we cant forget fibre(cotton) and dairy. both of these are dying or loss making sectors in the united states. its in absolute shambles. the guy making the money is the one who sells alfafa or hay. you can make more profits growing hay for feed than growing food for humans. and the guy who makes food for humans barely breaks even. and they are almost always collecting farm subsidies.

fertiliser and input companies(looking at you, bayer nee monsanto!) have their hooks on all commodity crops. because you have to see this from the vantage point of wall street. after we have introduced derivatives, futures and options etc..its a feverish speculative game. with algos running everything now, its certainly not about food anymore. it's a ponzi scheme. farms exist to make profits for inputs, tractor/machinery and seed companies. they are all publicly listed companies. connect the dots. and farms are propped up by tax payer dollars. pension companies and insurance companies buy farmland and play in the stock market. it goes back to paying pensions and medicare and benefits etc.

this house of cards may or may not come toppling down. but its still a house of cards. most of the feed and fodder grown..esp soy..was going to china. and as exports. we produce so much and we dont need as much. it helps balance our budget. or at least work with it. meanwhile..our waterways and aquifers are poisoned. farmers get caught in debt traps and imprisoned by unending credit. land rich but cash poor. so much poison in our waters and soil. the number of cancers have sky rocketed amongst farmers. i am not a luddite. but we cant ignore ground reality.

330 million is a lot. its not as much as the 1400 million of china or india..but it's still one of the more populous nations in the world. food security for this country is no joke. but we are holding on to depression era policy when it comes to farm subsidies.

a generic wiki entry on ag subsidies here: https://en.wikipedia.org/wiki/Agricultural_subsidy