A subset of ultra-processed foods, constituting approximately 25% of the American diet, contains harmful additives and hyperpalatable combinations that disrupt gut microbiota and promote metabolic dysfunction.

Study: Inhibition of calpain-mediated HMGB1 alleviates cardiac inflammation and dysfunction induced by ultra-processed foods

This study shows that eating ultra-processed foods can cause heart damage in mice by triggering inflammation, even without weight gain or higher blood sugar. This supports the idea that these foods contain harmful ingredients that mess with the body’s normal functions.

Study: Consumption of ultra-processed foods does not affect neuromuscular and cardiovascular fitness but alters gut microbiota in elite basketball players

This study found that basketball players who ate a lot of ultra-processed foods had less of two helpful gut bacteria that keep our metabolism healthy — even though they ate enough fiber. This supports the idea that these foods can mess with our gut, even if they don’t hurt athletic performance.

Study: Habitual Ultra-processed Food Intake Is Associated with Gut Dysbiosis and Pro-inflammatory Metabolite Profiles in Korean Patients with IBD.

This study found that people who ate more junk food like sugary drinks and snacks had more bad gut bacteria and more inflammation-causing chemicals in their poop. This supports the idea that these foods can harm your gut and metabolism.

Study: Consumption of Ultra-Processed Foods and Metabolic Parameters in Type 2 Diabetes Mellitus: A Cross-Sectional Study

This study found that people who ate a lot of ultra-processed foods (about 28–46% of their calories) had higher 'bad' cholesterol, which is a sign of metabolic problems — even if their blood sugar and weight didn’t change. This supports the idea that these foods can harm health.