As the others said it depends on several factors so and therefore it is different for everyone. However I would say the most people eat way too little fruit. Don't know why... Lately I read that only about 56 percent purchase fruits at least one time a week - the others more seldom.
And I would defenitely not say in general that you can't lose weight when consuming fruit. Of course it has sugar in it but not as much as chocolate or whatever. Plus there's no fat in it but rather a lot of important vitamins.