Since 1975, obesity has nearly tripled, now affecting over 650 million adults worldwide. Scientists know that diet can influence obesity—researchers have thought that ultra-processed or “junk” foods are part of the cause—but until recently, there have not been many studies to support the claim.
Ultra-processed foods such as soda, pre-packaged items, cold cuts and sweets are problematic because they are designed to be super tasty and can be addictive. The increased availability of cheap and tasty processed foods high in salt, fat and sugar is thought to have contributed to the obesity epidemic.
A recent study by scientists at the National Institutes of Health Clinical Center explored whether junk food really is the culprit for the obesity epidemic. There is evidence that eating ultra-processed foods is associated with obesity, high blood pressure and cancer. Studies have also shown that obesity is a major risk factor for heart disease, stroke, diabetes and several types of cancer. Many medical professionals feel we need to find ways to reduce junk food consumption or design more nutritious junk foods.
Researchers studied volunteers following an ultra-processed diet and compared the results to when the same people ate unprocessed foods such as fruits and vegetables, rice and beans and drank water. The two diets had the same amount of protein, fat, carbohydrate proportion, calories, sugar and fiber—but the participants only ate as much as they wanted at any given meal. The participants gained an average of two pounds on the ultra-processed diet during the two-week trial. But they losttwo pounds on the unprocessed diet, which suggests ultra-processed foods are a cause for weight gain. This is likely because they ate about 500 more calories per day during the ultra-processed diet.
The World Health Organization recommends eating lots of vegetables and fruits as part of a healthy diet and limiting added fats, sugar and salt. This study’s findings are a big step in the right direction for providing new evidence on a potential prevention and treatment strategy for obesity.
Joseph C. Watso, PhD, is a postdoctoral fellow at the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas and the Department of Internal Medicine at the University of Texas Southwestern Medical Center. Watso is interested in studying the role of lifestyle habits, such as diet and exercise, in maintaining heart and blood vessel health throughout aging.