Obesogenic describes environments, foods, or factors that promote obesity by encouraging excess energy intake or discouraging physical activity. The term is most applied to food environments: neighbourhoods dense with fast-food outlets and sparse in fresh produce, workplaces and schools surrounded by vending machines, portion sizes that have crept upward for decades, and marketing that normalises constant snacking. Researchers also describe obesogenic chemicals, endocrine-disrupting compounds hypothesised to disturb metabolism, though the evidence there is preliminary. The concept shifted obesity discourse from individual blame toward structural causes, arguing that willpower cannot reasonably overcome an environment engineered for overconsumption. Policy responses target the environment itself: restrictions on junk-food advertising to children, sugar levies, front-of-pack labelling, and urban design that makes active travel the easy default.