If I eat a bowl of cereal, even unsweetened, I am ravenous and unproductive 2 hours later. On the other hand if I have 4-5 eggs or tin of sardines I'm good for 4-5 hours.
Probably because it is basically an ad for a diet book...
It's still a well-cited article. If HN banned articles that end with an ad blurb, 3/4 of the content that makes the front page would violate that rule.