The National Institute of Health, NIH, conducted a prospective randomized study on a group of twenty healthy volunteers, average BMI=27. The recruits were randomly divided into two groups. First group of individuals consumed a diet of ultra-processed food for two weeks then unprocessed diet for two more weeks. The second group followed the same course but started with unprocessed diet then ultra-processed diet. Meals for each diet were prepared by dieticians to match in terms of calories and macronutrient content. Volunteers were allowed to consume as much or as little as desired. The study was recently published in the journal of Cell Metabolism.

The authors found that energy intake was greater during the ultra-processed diet with increasing consumption of carbohydrates and fat but not protein. Weight gain of around one kilo occurred during the ultra-processed diet period and highly correlated with increased energy intake. The authors conclude that eliminating ultra-processed diet, a less expensive and more convenient meal for thousands of Houstonians, decreases energy intake and results in weight loss.

This study further confirms our most important treatment recommendation at Houston weight loss surgery center: Not all calories are created equal. The first step in your weight loss journey is eliminating the ultra-processed food items from your diet. It is a hard step for many Houstonians, yet so crucial to achieve durable weight loss especially in the setting of gastric sleeve surgery. In my experience, the most common cause of weight regain after gastric sleeve surgery is the resumption of processed food intake. Gastric sleeve patients who stop cooking at home and resort to frozen foods and restaurant meals are at great risk of gaining back significant amount of weight. Ultra-processed diet disrupts the gut-brain axis that control appetite, satiety and food processing leading to increased energy intake and weight regain.

The industrialization of food and the increased consumption of highly processed meat, dairy and refined wheat products have greatly contributed to the obesity epidemic. Many theories have been proposed to establish a cause and effect relationship between processed diet and obesity. This study helps further confirm and better understand the effect of processed food on weight gain.