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Carbs like sweets, fries, white bread remain staples of U.S. diet

Americans are cutting back a bit on carbohydrates like sugary foods, refined grains, and starchy vegetables but these unhealthy options still make up about 42% of U.S. adults’ daily calories, a new study suggests.

From 1999 to 2016, the proportion of calories U.S. adults get from carbohydrates declined from 52.5% to 50.5%, researchers found when they analyzed nationally representative nutrition surveys. Over that same period, the proportion of calories from protein increased from 15.5% to 16.4% and the proportion from fat climbed from 32% to 33.2%.

The proportion of calories from so-called “low quality” carbs like sweets, white bread and French fries decreased from 45.1% to 41.8% during the study period. Calories from “high quality” carbs like whole grains and brown rice increased from 7.4% to 8.7%.

“Our findings show that we still have a long way to go to meet dietary recommendations,” said Shilpa Bhupathiraju, senior author of the study and a nutrition researcher at Harvard Medical School and Brigham and Women’s Hospital in Boston.

“This includes further increasing intakes of whole grains, whole fruit, non-starchy vegetables, nuts, and legumes, and lowering intakes of refined grains, added sugars, and saturated fat,” Bhupathiraju said by email.

Under U.S. dietary recommendations, adults should fill about half their plate with a variety of fruits and vegetables and make half of their grains whole grains, not white bread or white rice. (

Adults should also consume less than 10% of calories from added sugars, and less than 10% of calories from added fats. (

People in the study did cut back on calories from “low-quality” carbs by reducing their intake of added sugars, and fruit juice.

Increased consumption of animal protein, meanwhile, was driven by people getting more calories from poultry and eggs.

Higher plant protein intake was driven by increased consumption of whole grains, nuts, and soy.

The study didn’t assess whether specific factors impacted shifts in U.S. eating habits.

One limitation of the study is it relied on surveys asking people to recall and report everything the ate in the previous 24 hours. These 24-hour recall questionnaires don’t always give an accurate picture of how people really eat, the study team notes.

Researchers also lacked data on any health outcomes that might have changed as a result of shifts in eating habits.

Still, some changes for the better found in the study should help move Americans’ health in the right direction, said Linda Van Horn, author of an editorial accompanying the study and chief of nutrition at the Feinberg School of Medicine at Northwestern University in Chicago.

“Diets that are high in ‘complex’ or naturally occurring dietary carbohydrates are higher dietary quality than ‘refined’ carbohydrates that are processed and depleted of most of the vitamins, minerals and dietary fiber that are inherent in the naturally occurring carbs,” Van Horn said by email.

“Often refined carb foods contain high amounts of sugar (sweetened cereals) salt (snack crackers) or fat,” Van Horn added. “The U.S. diet includes far more refined carbs than naturally occurring, high fiber carbs, so an improvement in this area – e.g. more whole grain breads and cereals – is a good thing.”

“If all Americans would include more fruits, vegetables and whole grains they would greatly improve their overall diet quality while hopefully reducing intake of sugar, salt and saturated fats that are detrimental to health,” Van Horn said.

SOURCE: JAMA, online September 24, 2019.

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