Hi Gypsy,
I have just been reading the thread and thought I would offer some suggestions if that's ok? I am a qualified fitness instructor and personal trainer and have often worked with people trying to lose weight. My experience is that moderation is the key and healthy eating/exercise are absolutely essential.
Try not to lose too much too quickly or go on any 'quick fix' diets, tempting as it may be! You are right, the body needs essential nutrients, especially when going through fertility treatment.
I agree with Valentina that the GI diet is very good. It involves food with a slow release of energy, such as wholemeal rice, pasta etc. You could look at it online. There is plenty of information. Also, drink lots of water - this is because one of the key tasks of the liver is to emulsify fats. Therefore, if you are dehydrated the liver has to turn it's attention to dealing with that, rather than doing what it is meant to be doing. Another tip is to eat slowly. We have something called the satiety mechanism in the brain that lets us know we are full. It takes about 20 mins for that to kick in so if you eat slowly you feel full without eating too much.
Finally, exercise - just finding something you enjoy is the most important. I personally do a variety of sports, lots of cardiovascular but also resistance exercise(weights) as if you build some muscle it naturally requires calories as it is a 'live' matter (as opposed to fat, which is not) and so increases your metabolism.
Don't know if that's any help but if you want anymore info please let me know!
Good luck x