My guess is that eventually we'll confirm something like the "fat virus" hypothesis and be able to immunize kids (to some degree) against becoming obese. There

My guess is that eventually we'll confirm something like the "fat virus" hypothesis and be able to immunize kids (to some degree) against becoming obese. There exist human cold viruses such that if you give that particular cold to an animal, the animal gets fatter. We don't directly test these viruses on people due to ethical concerns - we're pretty sure they'd make people fat too, and there's no cure. But you can look at biomarkers for exposure and verify that people who've been exposed are more likely to be fat than those who haven't. Here's a study: http://www.ncbi.nlm.nih.gov/pubmed/17908526 http://www.ncbi.nlm.nih.gov/pubmed/17908526 Quote: "This review discusses the 5 animal viruses and 3 human viruses that have been shown to cause obesity and examines the evidence to date for virus-induced obesity. [...] Ad-36 causes obesity in chickens, mice, rats, and monkeys and was present in 30% of obese humans and 11% of nonobese humans. In twins discordant for infection with Ad-36, the infected twins were heavier and fatter than their cotwins."