I didn't down vote, but saying that losing weight is easy is like saying playing the piano is easy. In reality, they are indeed both easy, but you need determination and time.
Then the word easy is being used in two senses. Technically losing weight is extremely easy. It's a closed problem. It might be not-easy in a way that varies from individual to individual but to say that it's not-easy should be qualified in some sense to show that it's a psychological/will power/whatever problem and not because we have an incomplete understanding of nutrition.