Hi, Melissa.
I was in a similar situation. I had to lose weight (and make sure my BP behaved) to donate, and, since I'd already been on a low-fat diet for several years, a lot of the "low-hanging fruit" such as french fries, cold cuts, cheese, etc. had already been out of my diet; I'm also a semi-vegetarian. So, I had to get much more strict about how much I ate (till then, if it was under 5% fat, I more or less ate as much as I wanted, of, say, bread, pasta, etc.). Now I also count calories, and pay close attention so that I don't "waste them". One major way to avoid wasting calories is to cut out fruit juices, iced tea drinks, etc. Empty liquid calories are all around us!
My health plan approved 14 visits to a dietician after my donation last fall (I've had 3 visits so far). One tip he gave me was to eat two vegetables before each meal, especially one containing carbs. I've been using celery and carrots especially. It's helped--by the time I've chomped through all those veggies, I barely have any time left to eat the fattening stuff!
Another major thing is the sodium issue. I'm really, really careful about that. So I stir-fry fresh mushrooms (in sprayed Pam oil), say, instead of using the canned, heavily salted variety. I had never really noticed how much salt there is in bread. I have never baked anything before, but I'm debating learning how to bake my own bread to cut down on all that salt (bread is still a major element in my diet). {Does anybody know any good, simple, low-sodium bread recipes? I've found almost no packaged breads in the store without lots of sodium}.
I was expecting to restrict my sodium intake, but I didn't really expect the dietician to tell me that, next to sodium, I needed most to limit protein consumption in the wake of the donation. As part of that, believe it or not, he recommended that I choose 5% fat white (soft) cheese over the 1/2% version, because the lower-fat version has a higher protein concentration. Deliberately choosing a higher-fat version in order to lower protein intake is definitely a new one for me. As a near-vegeterian, I'd always tried to insure protein intake (such as, for example, by adding beans or lentils to rice to accompany stir-fried veggies). So, now, I actually try to limit that.
I have to agree with Sherri, alas, in emphasizing that this weight-loss business is for the long-haul, to deal with the somewhat elevated risk of hypertension, etc., for those of us in the one-kidney club. So that does have to be part of the equation in making the decision to donate. It's not just until donation. Even (and ever) after, we have to take good care of ourselves.
In my own case, that hasn't been so simple. My donation approval process was quite long, and all that time I felt I had the life of my potential recipient(s) in my hands. Soon after the donation, I felt I could relax a bit, since now it was "only me" to worry about--all that awful pressure of the extra responsibility (of watching my diet "for two", as it were) was now gone. So, I "broke training" to some extent, and re-discovered a few long-lost friends such as pizza--even while chomping away on the celery. So, it is an adjustment, but it's one that we really have to accept. In the end, everybody says that, when they try to live up to the proper post-donation practices, they really do feel much better. I'm sure that many donors actually extend their lifespan by learning new health practices before and after donation.
Overall, the best advice (besides watching sodium, protein, and avoiding getting dehydrated), is simply to eat less, and exercise more.
I keep hoping the docs advise me to eat more french fries and stop exercising, but it hasn't happened yet. So (weather permitting), I walk home from the inter-city bus, rather than taking the local bus home from the bus station. Things like that can help. By listening to interesting classes on my MP3 as I walk, I don't even notice that I'm exercising!
Good luck!
Snoopy