It can be mentally detrimental to weigh yourself once/week - especially since you'll also be dealing with that feminine hormonal water weight gain every month. Most of this stuff was written with men in mind, who don't have to deal with that kind of stuff. I know when I weigh myself weekly, I get very annoyed during those hormonal weeks when my weight isn't changing. I've found if I monitor my skinfolds and appearance and stay off the scale, I get less frustrated on my diet.