Ultra-Processed Foods

Introduction: Ultra-processed foods (UPFs) are increasingly prevalent in modern diets, characterized by high levels of refined carbohydrates, fats, sugars, and additives. Recent research highlights significant concerns regarding the health impacts of UPFs, revealing that they may contribute to a range of metabolic, cognitive, and immune system issues. This summary synthesizes key findings on the science of ultra-processed foods, their impact on health, and the urgent need for further investigation and public health interventions.

Key Findings:

  1. Addictive Properties: A recent study published in The BMJ indicates that ultra-processed foods can be as addictive as smoking. The research suggests that these foods, high in refined carbohydrates and fats, can induce brain changes similar to those observed with addictive substances (BMJ, 2023).

  2. Impact on the Gut Microbiome: UPFs can significantly alter the gut microbiome, reducing its diversity and abundance of beneficial bacteria. Arpana Gupta, co-director of the Goodman-Luskin Microbiome Center at UCLA, notes that a diet rich in UPFs can negatively affect immune function, stress response, and neurotransmitter production, all of which influence mental health (WSJ, 2024).

  3. Cognitive Impairment and Stroke Risks: Research published in Neurology suggests that a higher intake of ultra-processed foods is associated with increased risks of cognitive impairment and stroke. This correlation underscores the potential cognitive harms of a diet high in these foods (Neurology, 2023).

  4. Immune System Effects: UPFs have been linked to changes in immune system functioning. Studies on mice have shown that exposure to emulsifiers, common in UPFs, can damage the gut's mucus barrier, increase gut permeability, and trigger inflammation. These changes may contribute to inflammatory bowel disease and potentially autoimmune disorders (ScienceDirect, 2024).

  5. Metabolic and Obesity Issues: Diets high in UPFs are associated with higher calorie intake and weight gain compared to diets with similar caloric content but without UPFs. This trend suggests that UPFs may contribute to obesity and chronic inflammation. Both factors are linked to decreased microbial diversity and altered gut permeability, which further impact immune function (JAMA, 2023).

  6. Health Risks: A comprehensive review in February 2024 identified 32 adverse health effects associated with UPFs, including increased risks of heart disease, cancer, type 2 diabetes, mental health issues, and early death. This review highlights the extensive and varied health risks posed by a diet high in UPFs (Lancet, 2024).

The Science of Ultra-Processed Foods

  • A recent study published in The BMJ is reporting that ultra-processed foods can be as addictive as smoking: https://www.bmj.com/content/383/bmj-2023-075354

  • Foods high in refined carbohydrates and fats can cause changes in the brain.

  • Eating a typical American diet full of ultra-processed foods can change your microbiome so that it is less diverse and has fewer types of beneficial bacteria, said Arpana Gupta, co-director of the Goodman-Luskin Microbiome Center at the University of California, Los Angeles. The gut microbiome refers to the microbes that live in the digestive tract. It influences immune function, the stress response system and the production of neurotransmitters like serotonin, all of which affect mental health: https://www.wsj.com/health/wellness/ultra-processed-food-brain-health-7a3f9827

  • Recent research published in the journal Neurology suggests that people who consume more ultra-processed foods may indeed face higher risks of cognitive impairment and stroke compared to those who eat fewer processed foods.

  • There's a growing body of evidence that ultra-processed foods may affect how our immune system works. This may explain why some studies have linked ultra-processed foods with inflammatory bowel disease and potentially autoimmune diseases.

  • Studies on mice have shown exposure to low concentrations of emulsifiers can weaken the gut's mucus barrier. This can make it easier for microbes (including harmful ones) to cross in and out of the gut. Changes in the mucus barrier's integrity also correlated with higher levels of inflammatory markers. These are signs the body's immune system is activated.

  • Ultra-processed foods are also linked to changes in the gut microbiome's composition. Diets high in saturated fats, sugars, salt and additives (such as emulsifiers) have all been shown to decrease the abundance of beneficial bacteria that help maintain the gut barrier in mice. There was also an increase in harmful bacteria that triggered inflammation.

  • For example, one trial showed that a diet high in ultra-processed foods led to higher calorie intake and weight gain compared to a diet without any ultra-processed foods that were matched for calories and sodium levels. Over time, highly ultra-processed diets may contribute to obesity and chronic inflammation. Both factors are closely linked to alterations in the gut microbiome – including decreased microbial diversity and increased gut permeability – which may subsequently affect immune function.

  • In February 2024, the world’s largest review of its kind found UPFs were directly linked to 32 harmful effects to health, including a higher risk of heart disease, cancer, type 2 diabetes, adverse mental health and early death.

Thesis: Ultra-Processed Foods Encourage Obesity

The rapid increase in obesity rates over the past 20 years, despite stable total caloric intake, may be attributed to UPFs causing maladaptation in metabolism. Obesity rates are up 30% in the last 20 years even though total caloric consumption hasn't changed.

Our thesis is these foods cause us to gain weight through mechanisms that involve alterations in gut microbiome composition and function, leading to chronic inflammation and metabolic dysfunction.


  • BMJ. (2023). "Ultra-processed foods and their addictive properties: A comprehensive study." The BMJ. Retrieved from The BMJ

  • Gupta, A. (2024). "Impact of Ultra-Processed Foods on Gut Microbiome and Mental Health." Wall Street Journal. Retrieved from WSJ

  • Neurology. (2023). "Ultra-Processed Foods and Cognitive Impairment: A Risk Assessment." Journal of Neurology.

  • ScienceDirect. (2024). "Effects of Emulsifiers in Ultra-Processed Foods on Gut Barrier and Inflammation." Journal of Experimental Medicine.

  • JAMA. (2023). "Caloric Intake and Weight Gain from Ultra-Processed Foods." Journal of the American Medical Association.

  • Lancet. (2024). "Health Risks Associated with Ultra-Processed Foods: A Global Review." The Lancet.

Last updated