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Nearly 60 percent of what Americans eat is junk — ultra-processed foods loaded with sugar, salt, fat and all the other stuff we are not supposed to snack on, a new study finds.

The data pretty clearly explain why two-thirds of Americans are obese or overweight, and why rates of diabetes and heart disease are soaring, the team of Brazilian and U.S. researchers said.

Pizzas are seen in a kitchen. Tim Boyle / Getty Images file

“The most common ultra-processed foods in terms of energy contribution were breads; soft drinks, fruit drinks and milk-based drinks; cakes, cookies and pies; salty snacks; frozen and shelf-stable plates; pizza and breakfast cereals,” Dr. Carlos Augusto Monteiro of the University of São Paulo and colleagues there, and at Tufts University in Boston, wrote in their report.

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“Meat, fruit and milk provided the most calories among unprocessed or minimally processed foods,” they added.

Fresh fruits and vegetables should make up most of what we eat, nutritionists and public health officials alike say. But the study found they contribute just under 650 calories a day in the average 2,000 calorie-a-day diet.

Related: Starchy Diet May Raise Lung Cancer Risk

Starchy, fat-laden, processed foods raise rates of heart disease and diabetes, as well as cancer, studies show. People who eat more fruits and vegetables have lower rates of all these diseases.

The researchers used information from a large national study of U.S. health that includes a detailed food diary. They focused on 9,300 adults and children.

“Ultra-processed foods comprised 57.9 percent of energy intake, and contributed 89.7 percent of the energy intake from added sugars,” the team wrote in the British Medical Journal’s online publication BMJ Open.

More than 20 percent of calories in the ultra-processed foods came from sugar. Federal eating guidelines say people shouldn’t get any more than 10 percent of calories from sugar and some nutritionists say it should be even less than that.

Related: Cutting Sugar Had Big Effects in Kids

“We confirmed the excessive consumption of added sugars in the USA,” the team wrote.

“We also provide new evidence that ultra-processed foods represent more than half of all calories in the U.S. diet, and contribute nearly 90 percent of all added sugars.”