Shake up your sugar consumption (or some things change, others stay the same). The new guidelines offer a few important updates. For the first time, they recommend limiting the number of calories derived from sugar to 10 percent of your daily caloric intake. Daily limits on cholesterol, which have been recommended for years because of cholesterol's apparent connection to heart disease, have been nixed. However, the guidelines contain many of the same core principles that they have in previous iterations. People should fill their plates with more fruits and vegetables, and eat more protein in the form of fish and legumes instead of red meat and chicken. Saturated fat shouldn't make up more than 10 percent of a person's daily calories.
Guidelines can change because of science. Guidelines change every five years from a combination of two forces that sometimes oppose one another. The first is science. Science is an iterative process to which new evidence and studies are added all the time. That means that scientists rarely reach a consensus, and even experts sometimes disagree on which conclusions to draw from contradictory studies. Take, for example, this fairly public debate about what makes a "heart healthy" diet. While it's great to get a glimpse behind the scenes of the conversation surrounding nutrition and to know that there's rigorous debate, it's not very useful for a person looking for guidance about a heart-healthy diet.
Guidelines also change because of politics. Often, guidelines like these can feel like contorted descriptions of intuitive dietary principles. That's because, as Vox and Slate have pointed out, science is only one part of the process to formulate the guidelines—lobbyists and food industry representatives exert a lot of influence. The authors of the guidelines are forced to use euphemisms and linguistic contortions to talk about foods we shouldn't eat--"sugary drinks" instead of sodas, "saturated fat" instead of red meat--in order to tiptoe around big industries. Because the dietary guidelines influence things like school lunches, food stamps, and doctors' recommendations to patients, they can have a tangible economic impact for these industries. That sort of sway might explain why the guidelines feel like they're written in legal-ese, and why recommendations for red meat or sodium didn't change from the 2010 guidelines, despite growing debate and awareness of their negative heath effects.
It's not impossible to eat healthy. Maybe you won't follow those guidelines exactly, sitting at home with a food journal and a calculator every evening. But you don't need to do that to still eat well. In a culture where we're more inclined to ping-pong between excessive and overly-restrictive diets, it doesn't hurt for us to parse through the noise and hear the words, "Everything in moderation."