I wouldn't say I followed her advice exactly. I didn't care for her book but had heard that her nutrition info was real good so I skimmed that. I know I hadn't gained the recommend amount by 24 weeks (I think I had maybe gained 19 by then and didn't find out about the twins til 26 weeks). I just wasn't hungry! It was very hard to get myself to eat much, though I tried. I aimed for 100-120g of protein a day (which I know is less than a lot of people here say, but this is what my mw told me and was about all I was able to do anyway). I didn't know about the gallon of water a day (which I'm not too sure about - there IS a point at which too much water is harmful and a gallon is an awful lot). I did take some herbal supplements to support my liver & such, as recommended by my mw. I don't remember what else. When I first found out about the twins I tried SO HARD to get more protein in but when it got to the point that I literally had tears dropping into my food b/c I just couldn't force another bite I realized that something had to give. I was only going to make myself vomit at that rate and then what good would it have done to eat it anyway? So I cut myself some slack and worked hard to log what I could eat so it was easier to make sure I at least met my minimum, and I did. Anyway, back to your question!
I gained 39 lbs (which was less than with my first singleton), no swelling/water-retention, lost it all in 9 days, and at almost 2 years pp I'm down an additional 20lbs thanks to nursing twins!
My twins weighed 6 lbs 14 oz & 7 lbs 13 oz. I believe strongly that genetics plays at least as big a role in baby-size as diet, although diet is of course very important too!