Health authorities have been advising the public for years to eat only fresh and home-cooked food as much as possible to keep a healthy weight. However, a recent study found out that a lot of Americans have not been following this guideline and, in fact, have been including "ultra-processed" foods in their diet.

Ultra-processed foods are industrial formulations that try to imitate the taste of fresh food. These are not our usual, salt-sugar, oils and fats used in the kitchen but so much more as to make the food taste good and fresh with minimal culinary preparations.

The study, led by researcher Euridice Martinez Steele from the department of nutrition in the School of Public Health at the University of Sao Paulo in Brazil, showed that ultra-processed foods account for 57.9 percent of energy intake. In terms of sugar content, ultra-processed foods are found to contain 21.1 percent of calories, which is said to be eight times higher than processed foods that have 2.4 percent added sugar and calories.

The findings also declared that 82.1 percent of Americans have not been following the recommended limit of 10 percent energy from added sugars found in processed and ultra-processed foods.

"Decreasing the consumption of ultra-processed foods may be an effective way of reducing the excessive added sugar intake in the U.S.," Steele said.

So what, actually, are examples of ultra-processed foods? Steele said in an interview that they include sodas, sweet or savory packaged snacks, candy and desserts, packaged baked goods, instant noodles and soups and reconstituted meat products, such as chicken and fish nuggets.

Processed foods, on the other hand, are those that have added sugar, salt and other substances for a more enhanced, yummier taste like canned foods or simple breads and cheese.

Steele further said that the best way to keep away from the calories that may lead to weight gain is to eat healthy and fresh foods.

Statistics from the Centers and Disease Control and Prevention said that more than one-third (34.9 percent, or 78.6 million) of U.S. adults don't have a healthy weight and are obese. Obesity is linked to life-threatening diseases like heart disease, stroke, type 2 diabetes and certain types of cancer, which are some of the leading causes of preventable death.

The study was published in the March 9 issue of the journal BMJ Open.