Hi. You are going onto what's called the 'Basal/Bolus' regime which is the most flexible and same as mine and many others. The good news is that the only thing that happens when you start is that your blood sugar will go down! My DN is excellent and she explained everything, but they obviously vary. You only gain weight with insulin if you have too many carbs. Assuming you will be carb counting either from Day 1 or shortly after (i.e. adjusting the Rapid to the carbs at each meal) you need to be sensible with the amount of carbs. It's tempting to start having all those cakes etc that you used to have; just be sensible and your weight gain will be minimal. As I'm quite thin my DN started me on 4mm needles; the shortest you can get. Discuss having the shortest needles you can for your body skin fat. Hypos are obviously the thing to watch. I've not had one in a year since starting although have come near it. You just need to find out what works for you in the first few weeks and discuss with the DN. Do ask any specific questions. BTW I've gained 1.5Kg from 61Kg in 1 year