I gained weight in the past on Depakote (valproate), Zyprexa and Amitriptyline. Probably on others, too (Lithium, Seroquel, and Risperdal), but not a lot - this "trio" was the culprit for my gaining close to 100 lbs. I did not weigh myself when I was at the ideal weight so I do not have an exact number of the gain.

I weigh about 229 pounds being a 5'5'' woman. This is down from my worst weight, which was 238 - I was able to reduce the weight a little bit (and luckily noticeably in the belly area) by exercise alone last year. I then had a leg injury from wearing wrong shoes and did not exercise for several month. I have just been released to all exercise and cannot wait to see if I can reduce weight further.

Clozapine is notorious for weight gain and other metabolic side effects, but it is also more effective than other AP's, per my IOP psychiatrist. I can see how it would be a very tough choice to make, but also can definitely see how the circumstances may make clozapine non-negotiable.

I took a low dose of Zyprexa (again - last time I was on it several years ago) for a month and a bit recently and managed NOT to gain weight, by being very careful, but... my cholesterol still went up, so I went off it and am keeping it in my stash as a PRN. FWIW, this is what apparently helped me NOT to gain weight on Zyprexa this time, as this may help you in your very difficult situation:

1) drink 16-20 cups of fluid daily (for me, it is mainly black and fruit tea)
2) eat a whole artichoke with mayonnaise every other day (it takes very long and you get tired of the process of eating by the end)
3) eat soup daily
4) eat butter, sour cream and drink half-and-half in order to get full more quickly - avoid being completely low fat
5) reduce refined carbs
6) plenty of vegetables, fruits, whole grains, and legumes (this one is obvious, but I thought I'd still mention it)

I think the very key part is drinking 16-20 cups of liquid each day. That really keeps you full. If I have eaten my meal, and I use measuring cups for portion sizes, and am still feeling hungry, I make tea. By the time the tea has cooled off, I drink it and feel hunger no more. So to the extent that I can make sense of it, the most important part is consuming as high a volume of fluids as possible. Note that this level of fluid consumption is NOT pleasant - say, in the morning I drink two cups of weak coffee with half-and-half for pleasure, eat breakfast, wait 15 minutes, and then drink a whole pot of tea - 4 cups. Drinking the tea is NOT pleasant - my tummy is full and if not for the preventative benefits, I would not drink it, but it helps me avoid migraines and, as I also noticed, keeps me feeling full.