Well, I am quite overwhelmed by the amount and detail of the responses to my query (or was it a rant, sorry). Thank you all, I have learnt a great deal about SW in the last couple of days and am now much more informed and more able to support her.
It seems that we both have some faulty ideas about this diet and it seems there are many more variations than alternating red and green days which is how she (we) has always approached it.
To answer some of the questions.
She joined SW in Sept. 2004 and was 13st 0lb and she is still 13st 0lb now. There is only 1 weight recorded in the back of the book so she didn't go to meetings. Also the books are rather out of date now.
At 5'9'' her supposed (from BMI charts) target weight is 10st 7lb. When we met she was 9st 9lb and maintained that for years apart from when she was pregnant of course. We agree that 9st 9lb is way too light now, however.
Why am I posting these questions? Basically I told her that SW wasn't working for her and that she should try some other approach. She (rather illogically to my mind) says it does work and wants to stick to it. So in order to be a supportive husband I need to learn how to make it work for her. Since I work from home I do quite a bit of cooking evening meals so need to get it right.
At the start of October she bought a WiiFit, she already does pilates classes and a 2 mile walk weekly. The WiiFit was totally her decision, I have always said they were a waste of time but have had to eat my words since it's loads of fun and does a marvellous job of weighing you and tracking progress. I have lost 4 pounds since getting it and she has gained a pound much to her disgust.
Alternating carbohydrate and veggie days doesn't seem to be cutting it. I think the suggestion of more red days is a good one. We need to mix it up a bit, use the WiiFit to monitor progress and see what suits us.
Sample menus?
Breakfast she either has porridge, half a melon with low fat Greek yohurt or scrambled eggs on toast.
Lunch. Salad from school kitchen.
Evening meal. Chicken breast (no skin) cooked with vegetables (peppers, carrots, leaks, broad beans etc) and tinned chopped tomatoes to make a sauce and wet it a bit. On green days swap the chicken for quorn and add potatoes.
She also takes 2 pieces of fruit to eat during the day at work.