I agree that this article got it wrong - though in a rather different sense. The movie itself does not blame obesity for the world's collapse, but rather blind consumerism. If you watch the "Buy 'N' Large" commercials in the film and take a look at the portraits in the captain's chambers, you'll notice that they are images of rather trim individuals who later "evolved" into these blob like creatures. The movie warns that if people continue to follow this path of blind consumerism, that these are the consequenses: A world left to rot and people who are not far behind. And while obesity is easily symbolic of this sentiment, it is not the cause.