Anybody know much about Weight Watchers?

[Brett's Honey]

My 13 yr old step-daughter is 5’ 7” and weighs 248 lbs. She’s gained 37 lbs in the last 18 months, so she’s not gaining as quickly as I had thought, but she still needs to lose 100 lbs. I took her to her doctor for a consultation yesterday, and the doctor highly recommended her joining Weight Watchers. There is supposedly a really good group in a nearby college town that consists of mostly younger girls. Does anyone out there have any knowledge of, or comments about Weight Watchers?
(And before someone suggests looking into the underlying problems here, yes there most likely is a reason this over eating habit started. It began when she was 6, after she witnessed her mother’s murder, after which the house was set on fire, and if she and her sister not been able to get themselves partially untied and escape the house, they would surely have died too. And of course following that, were the police interrogations, picking out mug shots, interviews with seven criminal psychologists, and having to state over and over that their Dad didn’t do it, despite their maternal grandmothers trying to plant those thoughts into their minds. So she’s had a tough time these past few years. But she’s 13 now, and starting to hate the way she looks. And of course, its time to get “boy crazy”.
Her Dad tried to establish better eating habits for her when she was younger, and both grandmothers would say “Don’t be mean to her – let her eat. She’ll grow out of it! Didn’t happen! She’s doing very well with her Mom’s death, considering how traumatic it was, and we have a good, kind of “special” step-mom/daughter relationship since she lost her Mom and I lost my only daughter.)
I really want to help her get down to a healthy weight where she'll be happy and feel better. Any suggestions are welcomed!!!