You need to allow yourself one. One rusk and then you eat it slowly, as you would if it was the last one. Enjoy the texture in your mouth and the taste. Savor the flavour and take in the scent. Tell yourself that this is enough. Remember your body will have cravings when it needs certain foods. So allow yourself one of those cravings. Discipline yourself to have that one and enjoy it to its fullest. When you have 2 or 6 you end up feeling so guilty and you dont enjoy it. Where as if its just one, theres no guilt only enjoyment. Dont beat yourself up. Just keep on working hard.