lazy loading with doctrine one to one mapping

I am having a hard time finding the correct result for this.

I have one to one mapping. There are two tables:

/**
* @ORM\Table(name="users")
* @ORM\Entity
*/
class Users {

   /**
    * @ORM\OneToOne(targetEntity="UsersSettings", mappedBy="user",cascade={"persist"})
   */
   private $userSetting;

   //getters and setters
}

/**
* @ORM\Table(name="notifications_settings")
* @ORM\Entity
*/
class UsersSettings {

   /**
   * @var Users
   *
   * @ORM\OneToOne(targetEntity="Users", inversedBy="userSetting")
   * @ORM\JoinColumns({
   *   @ORM\JoinColumn(name="user_id", referencedColumnName="id")
   * })
   */
   private $user;
}

Whenever I fetch entity one as below:

$q = $this
            ->createQueryBuilder('u')
            ->select('u, r')
            ->leftJoin('u.roles', 'r')
            ->where('u.username = :username OR u.email = :email')
            ->setParameter('username', $username)
            ->setParameter('email', $username)
            ->getQuery();

Doctrine immediately performs join to usersSettings entity which I dont want:

SELECT t0.id AS id1, t0.username AS username2, t0.email AS email3, t0.password AS password4, t29.id AS id30, t29.is_notify_by_email AS is_notify_by_email31, t29.user_id AS user_id32 FROM users t0 LEFT JOIN users_settings t29 ON t29.user_id = t0.id WHERE t0.id = ?

Other types of mapping like OneToMany and ManyToOne performs lazy loading but in case of one to one mapping, I could not configure to lazy load. How can I lazy load this relation? I am using doctrine 2.3 and Symfony 2.1