Between 1975 and 2016, the prevalence of worldwide obesity nearly tripled up in number. According to the World Health Organization, in 2016, over 1.9 billion adults (aged 18 and above), were overweight, while more than 650 million of them were obese.
This begs for a question: what makes us gain weight? We might answer that fatty or sweet or salty foods make us gain weight, but that might not be the case. Researchers from the National Institute of Health conducted a study that suggested that it’s not just salt or sugar or fat that makes us gain weight — it is the quality of food we are eating, if they are processed or not.
The study, conducted by researchers at the National Institutes of Health, is the first randomized, controlled trial to show that eating a diet made up of ultra-processed foods actually drives people to overeat and gain weight compared with a diet made up of whole or minimally processed foods. Study participants on the ultra-processed diet ate an average of 508 calories more per day and ended up gaining an average of 2 pounds over a two-week period. People on the unprocessed diet, meanwhile, ended up losing about 2 pounds on average over a two-week period.
"The difference in weight gain for one [group] and weight loss for the other during these two periods is phenomenal. We haven't seen anything like this," says Barry Popkin, a nutrition professor at the University of North Carolina who has studied the role of ultra-processed foods in the American diet but was not involved in the current research.
Dariush Mozaffarian, dean of Tufts University's Friedman School of Nutrition Science and Policy, agrees that the findings are striking. He says what was so impressive was that the NIH researchers documented this weight gain even though each meal offered on the two different diets contained the same total amount of calories, fats, protein, sugar, salt, carbohydrates and fiber. Study participants were allowed to eat as much or as little as they wanted but ended up eating way more of the ultra-processed meals, even though they didn't rate those meals as being tastier than the unprocessed meals.
"These are landmark findings that the processing of the foods makes a huge difference in how much a person eats," says Mozaffarian. That's important, because the majority of foods now sold in the U.S. — and increasingly, around the globe — are ultra-processed.
And ultra-processed foods include more than just the obvious suspects, like chips, candy, packaged desserts and ready-to-eat meals. The category also includes foods that some consumers might find surprising, including Honey Nut Cheerios and other breakfast cereals, packaged white bread, jarred sauces, yogurt with added fruit, and frozen sausages and other reconstituted meat products. Popkin says ultra-processed foods usually contain a long list of ingredients, many of them made in labs. So, for example, instead of seeing "apples" listed on a food label, you might get additives that re-create the scent of that fruit. These are foods designed to be convenient and low cost and require little preparation.
(Image Credit: Christopher Flowers/ Unsplash)