This chart, extracted from the NIH website shows the recommended amounts of nutrients the average person over 4 years should be consuming per day. Most Americans are consuming higher amounts than are recommended -surprise!
This graph shows that Americans are overall improving their meat consumptions, but still are eating more (sometimes double) the recommended protein levels. Meat consumption is not an efficient way for humans to get energy. The energy goes from the sun, to plants, to live animals, and finally to human and energy is decreased at each point of the chain. It would be more efficient to get energy by eating plants directly. While there are many protein-heavy plants, most Americans are still inclined to get the majority of their protein from poultry, beef, and seafood. Although it is promising that the trend is going down for beef consumption, poultry and fish consumption are still rising. In comparison to the harms and inefficiencies the meat market makes to the world and to our own health, Americans need to decrease their intake of meats/poultry/seafood even faster and/or consume their proteins in other manners, such as from plants.
Additionally, this infographic shows that Americans have been consuming a lot of grains and sweeteners, many of which are corn based. Increased processed foods and added sugars are associated with health problems such as obesity, diabetes, heart disease, metabolic syndrome, and gout. Many artificial sweeteners are increasingly made from fructose corn syrup, increasing the demand for corn even more, and causing rippling affects in agricultural economies.
Ultimately, there needs to be a cultural change from consumers, corporations, marketers, government, and farms for America to eat the right amounts of foods to get the proper nutrients.