Obviously, there is something wrong with the food in US since the percentage of obese people has increased dramatically. Currently, around 7 in 10 adult Americans are obese and overweight (see statistics here and here). That leaves only 3 in 10 adult Americans with normal weight. Increased weight leads to increased health problems from diabetes, high blood pressure to osteoarthritis.
How did we get here? The best explanation I found was in presentations by Marion Nestle: watch this lecture. There were a few factors in the 1970s-1980s. Up to a point the farmers were paid to keep the land uncultivated. Then this changed and the government paid the farmers to grow crops. Suddenly, there was more food on the market. Another factor was a change in financial regulations and more money were available for Wall Street to use. Wall Street firms started to invest in the food industry and expected fast profits. The food industry became very competitive. It was a race to advertise products in order to sell as much as possible. Even at that time people already had enough calories but the food companies used other tricks to increase sales (added all kind of nutrients/supposed benefits, increased portion size). Another contributing factor was women starting to work and having less time at home to cook. What was not a factor according to Marion Nestle is a decrease in physical activity because people were not active in the 1970s-1980s anyway.
What can we do about this situation? I think everything starts with a healthy diet. But what is a healthy diet in the first place? You turn on the TV and there are tens of commercials about different products to help you lose weight. You go on the internet and there are all kind of diets promoted. We have to remember that the food industry is a business. Most diets advertised on TV, on the internet and in stores are a business too. However, there are people around the world with different habits/environmental conditions that already proved that certain lifestyles are better than others. In my opinion (no business for me) there are a couple of diets worth considering. One is the Mediterranean diet. The other one is the Vegetarian diet. Basically, both of these diets involve eating vegetables and less or no meat. One talk that I found particularly useful about diets is this lecture by David Katz.
For more information about the Mediterranean diet: Mayo clinic link and Healthline link. It is ok to skip the wine associated with this diet. The Mediterranean diet was shown to improve health in various studies (a good resource here). One population that has shown benefit from the mostly vegetarian diet is the Seventh day Adventist population in California (one of the articles here).
Another popular good source for information is Michael Pollan (one of his entertaining talks here).
After countless hours spent on the internet I think the bottom-line is what Michael Pollan said: eat food (real food, not processed food, not nutrients), not too much, mostly plants. For most people following these simple recommendations plus eating a variety of foods will bring all the necessary nutrients. More tips from Michael Pollan: here.
I think the food culture is actually changing in U.S. Farmers markets are more popular than ever. There are even more young people becoming farmers according to this recent article from Washington Post.