I've done SW so many times over the years, only to put it all back on and then some.
It does work for so many people, though. A close friend of mine has lost in excess of 7 stones on SW, and has maintained this for years. However, she is still a slave to SW IMO.
When eating out, be it at a restaurant or at a friend's/family member's house, it's very much a case of "Has this got butter/oil in it?" ... "Is that low fat yogurt?" ... "Is that fat free mayonnaise?" ...."Oh no, I can't eat that!"
Food and her relationship with it is still a major factor in her life, and it still causes tension between her and her DH, because she won't ever waiver from the plan. If she does, it's a major source of stress and tension and results in her feeling anxious and down, like she's failed and let herself down.
That's the thing with SW - once you step off the wagon for any length of time, you've probably had it, so people tend to be quite evangelical and fanatical about it, IME.
I'm now in my early 40s, and for the first time in my life I feel that I have a normal relationship with food. I have lost approximately 4 stones in under a year from a combination of smaller portions sizes, cutting out snacks in between meals, choosing healthier food and being very active.
It hasn't cost me a membership fee, or a weekly weigh in fee. I don't have to applaud endless people who have lost 6lbs overall, but have gained 5lb this week, etc etc. I'm not feeling guilty for not "staying to class." I feel liberated from decades worth of lose-weight-gain-weight cycles.
I finally KNOW that this weight loss is for keeps, because my attitude has shifted and resembles absolutely nothing of my old unhealthy attitude to food, which was very skewed & damaging, and was underpinned by all that is SW.
And going out to dinner, visiting friends, someone baking me a cake....I just love being able to eat those things in proportion, occasionally, without having to feel guilty or count syns. Waking up on a Monday & not thinking about "getting back on the plan" is a great start to my week!