I did the Brewer diet (to an extent; I was vegetarian & got the amounts of protein but not in the ways he described) during my twin pregnancy. The girls had TTTS & I was following a recommendation to add Ensure or Boost drinks 3x/daily to my diet. Within a week of increasing my protein with that, the girls' growth stabilized and their fluid levels evened out. So I called the Brewer Diet hotline and was fortunate enough to reach Dr. Brewer himself (I hear he passed away last year, maybe? He was very sweet - I feel very fortunate to have had this phone call) and he went on and on for about 45 minutes about all the research he'd done over the years (which found that yes, protein is linked to pg hypertension) and how he thinks it's such a shame that so many drs are willing to call 35 weeks term for twins, when they really need the extra time in there. Anyway, I held tight with the protein for a long time - and honestly, when it started to wear thin and I started to get lazy about it was when the girls' growth started to get all crazy again.
Also? I had no leg cramps. I suffered them terribly with my son, had nary one with the girls, and now I"m being lazy with the protein again in my 3rd (single) pregnancy and I get wicked cramps almost nightly.