I agree with what other have posted here. I am overweight and when I started pursing surrogacy my BMI was in the obese range... I didn't have a lot of weight to lose to get below the obese range BMI, but I took some time to lose the weight. I learned early on that the clinic we were using had a higher BMI limit than my agency, but for me it wasn't just about making it in under the limit; I really wanted to be healthier for the pregnancy, both for myself and my IP's and potential surro-babes. I knew there would be a higher risk of multiples and I was worried about hurting my back or increasing my risks for bedrest or other complications. I did gain some of the weight back on the cycling meds, too, so I was even happier to start out weighing less.
That said, I had my BMI tested at my ND's office using the machine they hook up to electrodes (to do a BIA) and then to you, and my BMI was several points lower (and not in the obese range) than what the agency/clinic calculated. While I am overweight and have body fat to lose, I also have a lot of muscle and I'm quite healthy. My ND said she'd be happy to write something and give those BIA results showing the detail of my body fat, lean body mass, and BMI associated with those numbers. She felt that I was much healthier than a lot of people who are much thinner. Obviously body weight/BMI are not the only indicators of health, but clinics and IP's have to use something in order to weed out women who truly aren't healthy enough to be a surrogate.
I ended up losing around 35lbs before getting pregnant. I gained 30lbs with my surrogate pregnancy (twins) (as well as a few lbs while cycling), and believe me I was happy not to have been carrying around 30 extra lbs on top of that!
As we'd all tell any newbie, take some time to research, research, research... and read, read, read! Use the SMO search function, follow someone who has completed a journey from the beginning to the end if possible, ask more questions, talk to your support system at home about it.... and in the time it takes you to do that, you can hopefully take off some of the weight and meet the guidelines of the agency and clinic of YOUR choosing. (FWIW, I found other agencies that would accept me at a higher BMI, but I wanted to use the clinic I chose after lots of research and communication and I am so glad I did!)
Good luck and welcome to SMO!!