Are microplastics in food a risk factor for obesity? Current evidence, mechanistic pathways and emerging health risks associated with human exposure

This report examines whether microplastics in food and the wider environment could contribute to obesity in humans. It synthesises environmental data, human biomonitoring, experimental studies, and emerging epidemiology to evaluate exposure routes, biological mechanisms, and public-health implications. Humans are exposed to microplastics mainly through ingestion (food, drinking water, packaged beverages), inhalation (especially indoor air), and early-life transfer from mother to foetus. Microplastics have been detected in blood, stool, lungs, liver, kidneys, placenta, breast milk, and other tissues, showing that exposure is systemic and begins before birth. Strong experimental evidence shows that microplastics and plastic-associated chemicals can disrupt hormonal signalling, metabolism, gut microbiota, inflammation, and oxidative stress—pathways that are central to obesity. These include endocrine disruption, insulin resistance, altered appetite regulation, microbiome dysbiosis, chronic inflammation, and interactions with high-fat diets and chemical co-exposures. However, despite this biological plausibility, there is currently no longitudinal human evidence proving that microplastic exposure causes obesity. Human data are mainly cross-sectional, methodologically heterogeneous, and limited by the absence of standardised exposure measurements. The report concludes that microplastics are a credible candidate for obesogens at the mechanistic level, but human causality remains unproven. It calls for standardised exposure assessment, long-term cohort studies, and intervention trials.