If you’re confused about all the conflicting dietary and nutritional advice out there, you’re not alone. Every week, it seems as if researchers are learning something new about the foods that will help us stay mentally sharp, slender and disease-free — as well as those foods that will make us sluggish, soft and bed-ridden.
There’s a reason for that, of course. Scientific knowledge is constantly in flux, with new findings and reinterpretations of data as time goes on. To keep up with it all, the U.S. government convenes a Dietary Guidelines Advisory Committee to review and summarize everything we know about nutritional research so far, with the hope that it will guide U.S. food policy and nutrition programs in schools, the military and other public institutions that prepare food, educate people about nutrition or provide food assistance.
The reports, published every five years, also serve as a useful look back at what we believed was the best way to eat and drink ourselves to health in previous generations. To celebrate The Huffington Post's 10th anniversary, we took a look at how nutrition and health research has evolved over the decade since our launch back in 2005.
How To Eat
Then: All about the calories
Back in 2005, the best nutrition research out there counseled Americans to count calories in order to control weight. It didn’t matter what proportions of food people ate -- instead, it was all about maintaining a healthy balance of calories eaten versus calories spent in exercise.
"When it comes to weight control, calories do count -- not the proportions of carbohydrate, fat, and protein in the diet,” wrote researchers in 2005. "Energy expended must equal energy consumed to stay at the same weight. A deficit could be achieved by eating less, being more active physically, or combining the two.”
In fact, the report goes so far as to explain to the concept of “discretionary calories,” as well as a complicated formula for calculating how many a person consumes per day. As it turns out, that was probably unnecessary.
Now: Be mindful about your food
The 2015 report doesn't exactly say that keeping within calorie limits isn’t important -- it is, assured 2015 committee member Miriam Nelson, a professor of nutrition at Tufts University. Instead of explaining how to count and calculate the calories allowed in a day, the 2015 committee emphasized lifestyle strategies and healthy habits to keep calories low. For example, eating with friends and family at a table (rather than alone in front of the TV) can have a big effect on how many calories are consumed in a single sitting.
The report also emphasized that a healthy diet should be high in "vegetables, fruit, whole grains, seafood, legumes, and nuts; moderate in low- and non-fat dairy products and alcohol (among adults); lower in red and processed meat; and low in sugar-sweetened foods and beverages and refined grains. All those meals can either add up to a healthy or unhealthy pattern of eating. Nelson called the change one of the big shifts in nutrition research from 2005 to 2015.
“The focus on just saturated fat or whole grains was just one piece of the puzzle, and the guidelines were historically fractionated that way,” Nelson told The Huffington Post. “But every person in the world eats a complement of foods over the course of the day, the week, the month, the year and a lifetime, and it’s that pattern of foods that dictates how healthy or not healthy you’re going to be."
The takeaway: Rather than obsessing over calories, the latest guidelines prompt Americans to start incorporating whole foods into their diets.
Eating Fat
Then: Fat avoidance was still king
Back in 2005, Americans were advised to limit their total fat intake to just 20 to 25 percent of calories per day. Saturated fat should be below 10 percent of daily calories, trans fat below 1 percent of calories and dietary cholesterol to 300 milligrams per day -- about the amount in 1.25 egg yolks -- all in an effort to reduce the risk of coronary heart disease.
Now: We're all about the avocados, eggs and nuts
The 2015 landscape couldn't be anymore different. There is no ceiling for the percentage of calories that should be consumed as fat, and dietary cholesterol is no longer a “nutrient of concern” when it comes to overconsumption (in other words, eggs are good again).
Notably, while the report agreed with previous recommendations to keep saturated fat (the kind found in dairy products and fatty meat) below 10 percent of daily calories, they added an important caveat: people should be replacing saturated fat with so-called “healthy” fats like polyunsaturated fat (found in fatty fish and sunflower oil) and monounsaturated fat (found in avocados, peanut butter and olive oil), not carbohydrates.
The reason for the changes, 2015 committee member Rafael Perez-Escamilla told HuffPost, comes down to a misunderstanding in previous years: In an effort to cut the fat, food manufacturers and people were replacing fats with added sugars and refined carbohydrates, which turned out to be just as bad (or even worse) for health.
“At the end of the day, if we compensate for lower fat by increasing higher sugar or carbohydrates, that is really detrimental for our health in terms of increased risk for obesity, diabetes, coronary heart disease and so on,” said Perez-Escamilla, an epidemiology professor at the Yale School of Public Health. Now, he explained, “the important thing is that the fat or oil that we consume is healthy, while staying within calorie [limits]."
The takeaway: Some fats are healthy for you, so don't be afraid to drizzle that olive oil or slice up some avocado!
Eating Sugar
Then: Sugar was one of the food groups
Back in 2005, the research linking added sugar and sugar-sweetened beverages and weight gain was only beginning to emerge. The 2005 Dietary Guideline report sums up the evidence tentatively:
"Although more research is needed, prospective studies suggest a positive association between the consumption of sugar-sweetened beverages and weight gain.” The report also suggests that reducing added sugars “may be helpful” in maintaining weight.
"In 2005, there was still confusion about whether this was related to excessive calories from fat or from carbs,” explained Perez-Escamila. "Now we know it's from sugars and refined carbohydrates."
Now: Avoid, avoid, avoid
In 2015, there is strong evidence that consuming added sugar and sugar-sweetened beverages is linked to obesity and type 2 diabetes, according to the 2015 Dietary Guidelines. There’s also moderate evidence that an excess of sugar -- more than 10 percent of daily calories -- is also linked to coronary heart disease and dental cavities.
The takeaway: Start thinking about soda as a treat, not a drink to go with your lunch.
Who's Responsible For A Good Diet? 
Then: A good diet comes from individual willpower
In the 2005 dietary guidelines, a healthy diet was all about what an individual could achieve for him or herself. Think portion sizes, calorie counts, physical activity and eating the right nutrients. While those things are still emphasized in the 2015 report, the committee has also expanded its view to include the other things that influence a person’s decisions to eat one item or forego another.
Now: It takes a village to eat well
For the first time, the new report factors in research on how environments like schools, offices and communities help keep us healthy or drag us down into lifestyle patterns of obesity and chronic disease.
“Another big difference from 2005 is that we looked at the food environment,” said Nelson. "It’s not just about individual behavior change; it’s about systems change.”
For instance, does a school offer healthy foods and opportunities for exercise and physical activity? Does a cafeteria price healthier foods cheaper than junk foods? Are our communities and cities developed in a way that encourages walking, or prioritizes green spaces for community members to use at their leisure? These are just some of the examples the committee lists when thinking about how environments affect individual eating and exercising behavior.
The takeaway: Struggling with your weight? Look around you. What are the changes you can make to your work or school environment that would encourage physical activity and healthy eating?
The Environment
Then: Climate change is a thing Al Gore talks about
The 2005 guidelines didn’t say one word about the sustainability of a diet or food production’s effect on the environment.
Now: Climate change affects what we eat and what we eat affects climate change
The 2015 guidelines are also notable in that they considered, for the first time ever, the impact that our diets have on the environment. In other words, thinking about the sustainability of producing a certain food should factor into what we choose to eat, explained Perez-Escamilla.
“The diets that are the healthiest for the planet are also the healthiest for human beings,” said Perez-Escamilla. “The simple fact is that the food choices we make do have an impact on the environment and climate change.”
Take, for example, red meat. Because cows and other domestic livestock are produced for human consumption, the large amounts of methane gas they produce are considered “human-related emissions” and account for 26 percent of all the methane emissions in the U.S., according to the U.S. Environmental Protection Agency. This methane, in turn, traps radiation in our atmosphere, contributing to global warming. If more people can choose fish or poultry over beef, then the guidelines will have accomplished a significant goal, said Perez-Escamilla.
The takeaway: Load up on plant-based sources of protein and eat certain meats sparingly.
Working Out
If there's one thing the reports share, it’s a warning that most Americans aren’t getting the exercise they need to maintain a healthy weight and stave off chronic disease. But the way these reports mention it varies somewhat.
Then: Get a workout in every day
In 2005, the guidelines recommended at least 30 minutes of moderate physical activity on most days to see health benefits, while some adults may need 60 minutes of exercise on most days to prevent unhealthy weight gain. Adults who had lost weight and didn’t want to regain it may have to do 60 to 90 minutes of exercise on most days to prevent gaining it all back, the report warned.
Now: What matters is the bigger picture
In 2015, the report cited recommendations that were about the same, but shifted the daily dose to a weekly one (150 minutes of moderate physical activity per week). Nelson called it “good news” for those with demanding or varied schedules. The report also added this sobering assessment of how Americans currently stack up: "Unfortunately, the vast majority of Americans do not get the physical activity they need; only 20 percent of adults meet both the aerobic and strength training recommendations and less than 20 percent of adolescents meet the youth guideline."
The takeaway: Get your exercise in during times that work for you.
So much has changed in the past decade that everyone is bound to find at least one thing they need to change about their lifestyles to get healthier. The good news, amidst all this change? We've got to admit things are getting better, to paraphrase a few Beatles.
"The research helps to progress things so that we're always moving forward," Nelson agreed. "Otherwise we would be static and we wouldn’t learn new things."