Abstract

A worldwide epidemic of obesity began around 1980 in developed and developing countries. Usual explanations for obesity such as diet and exercise are insufficient to explain the epidemic. An environmental etiology seems obligatory. Adenovirus 36 (Adv36) infection causes obesity in multiple species of animals, with increases in body fat of 60%-150%. Presence of Adv36 antibodies is specific for past infection. Worldwide, about 30% of obese adults and children and ~15% of non-obese have been infected. Mechanisms are a direct effect on adipocytes, with both hypertrophy and hyperplasia. It seems likely that Adv36 is a major contributing factor to the obesity epidemic.