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New research finds that most U.S. adults overestimate the quality of their diet and mistakenly believe their food choices are healthier than they actually are. 10’000 Hours/Getty Images
  • New research indicates that most people are not able to accurately assess the quality of their diet.
  • Most think they eat more healthier foods than they really do.
  • The ones who are the most accurate, however, are the ones who maintain a less healthy diet.
  • Your overall pattern of eating is what matters the most, experts say.
  • Nutrition experts say there is room for an occasional indulgence as long as you are eating healthy foods most of the time.

When asked whether they are eating a healthy diet, many people are quick to say they think they are eating pretty well. However, a new study indicates that they may not be as accurate as they think they are.

Most people studied had a hard time assessing the quality of their diet, according to lead author, Jessica L. Thomson, PhD, a research epidemiologist with the U.S. Department of Agriculture’s Agricultural Research Service in the Southeast Area.

However, those who were able to most accurately assess the quality of their diet were those who perceived it to be less healthy. In those cases, they were almost always correct.

Thomson will be presenting her team’s findings this week at Nutrition 2022 Live Online, which is being held on June 14-16 at the annual meeting of the American Society for Nutrition.

The research team’s goal was to learn whether that one simple question could be used as a screening tool for nutrition studies, rather than the more detailed questionnaires that are generally used.

“We felt it was important to study whether adults can accurately assess the quality of their diet because a simple self-assessment tool may be useful when designing nutrition interventions,” said Thomson.

“Of course, such a tool would only be useful if perceptions are accurate,” she added.

To conduct their study, they used data from the National Health and Nutrition Examination Survey (NHANES).

NHANES is a nationally-representative survey of American adults which is done every two years.

People who take part in the survey must complete 24-hour dietary recall questionnaires, as well as rating the overall quality of their diet. They are asked to rate it as either poor, fair, good, very good, or excellent.

The information provided was used by Thomson and her colleagues to rank the quality of people’s diets.

What the researchers found after examining the data was that the scores calculated by the researchers based on people’s reported food intake was significantly different from how people rated their dietary quality themselves.

In fact, out of 9,700 people, about 85 percent of them (about 8,000 people) got it wrong. Further, out of those people who inaccurately assessed how good their diet was, nearly 99 percent of them felt their diet was better than it really was.

The people who did the best at rating the quality of their diet were those who rated it as poor.

These people were correct 97 percent of the time.

On the other hand, only 1-18 percent of people in the four other categories were on the mark in how they perceived their nutritional intake.

“Based on our findings, we recommend that efforts continue to educate adults in the United States about components of a healthful diet,” said Thomson. “We also feel that work is needed to understand what adults consider when thinking about the healthfulness of their diet.”

To help clarify what comprises a healthy diet, Healthline spoke with Catherine McManus, PhD, RDN, LD, assistant professor at Case Western Reserve University School of Medicine.

She said it’s really about what you do the majority of the time.

“The field of nutrition really focuses in on one’s overall dietary pattern,” said McManus, “because it is ok to eat out at restaurants, enjoy a slice of cake, or have some potato chips occasionally, just as long as these food items fit into an overall healthy dietary pattern.”

She advises that you can determine if your overall dietary pattern is healthy by following certain recommendations, including:

Eat nutrient-dense foods

Nutrient density refers to the ratio of nutrients, like vitamins and minerals, to how many calories are in a food.

“If you eat a lot of foods that are not nutrient dense (e.g., desserts, pretzels, potato chips, fried foods), you’ll need to overconsume on calories to reach your daily nutrient requirements,” McManus explained.

Watch your portion sizes

McManus said that a portion is the amount you choose to eat at one time.

“Basically, all foods/beverages can fit into a healthy dietary pattern, but for foods that are less nutrient dense (e.g., desserts, sugar sweetened beverages, many snack foods), we want to limit the frequency they’re consumed, and the portion being consumed, because they provide calories, but are very limited in essential nutrients, like vitamins and minerals,” she said.

Eat plenty of fruits, vegetables, and whole grains

“Fruits, vegetables and whole-grains are nutrient-dense and are filled with essential nutrients, like dietary fiber, folate, zinc and vitamins A, C and E,” said McManus.

Eat plenty of fiber

McManus pointed out that most people in the United States do not get enough fiber.

She said you should shoot for at least 14 grams for every 1,000 calories you eat.

This will help your digestion, heart health, blood sugar control, and weight.

Limit added sugars and refined grains

“These are examples of two foods that have a very low nutrient density, meaning they provide calories with little to no nutritional value,” said McManus.

They have been linked with increased risk for chronic conditions such as:

  • obesity
  • cardiovascular disease
  • type 2 diabetes.

McManus further noted that, while fruit does contain sugar, it is natural sugar rather than the added sugars that are found in processed foods.

Therefore, eating fruits shouldn’t be viewed with the same level of concern as processed foods containing added sugars.

Limit your sodium intake

While sodium serves many important functions in the body, like fluid balance and muscle and nerve function, Americans tend to eat too much of it, said McManus.

This can increase risk for high blood pressure, heart disease, and stroke.

She said the Dietary Guidelines for Americans recommends keeping your intake to under 2,300 mg per day.

Limit trans fats

“While it’s important to consume all fats in moderation because they are calorically dense,” said McManus, “it is especially important to limit those that have additional established negative health implications, such as trans fats.”

Trans fats, which are formed when liquid oils are turned into solid fats, can raise your “bad” low-density lipoprotein (LDL) cholesterol, as well as lowering your “good” high-density lipoprotein (HDL) cholesterol, she explained.

This can increase your chances of developing cardiovascular disease and stroke.