BBL on a petite woman: I am 4'9 and my normal weight is around 110lbs.

The question of the perfect weight as it relates to BBL is fast becoming one of the most commonly posted questions in the RealSelf community. While it is true BBL is a weight sensitive procedure (in the sense that you need fat to achieve your result), it is never a good idea to pursue short term changes for surgery.
While there is no absolute number (lbs.) in terms of weight for undergoing liposuction with autologous fat transfer, the optimal candidate has reached a healthy and stable weight (preferably with a BMI less than 30, which is associated with a lower incidence of complications).
Potential candidates should also have adequate fat reserves for transfer. This becomes especially important when one considers the anticipated rate of fat resorption and graft loss. I typically recommened patients aim for at least 500 cc transferred per cheek. This would amount to 1 liter of fat (not lipoaspirate) after processing. Candidates with inadequate fat reserves are likely to be disappointed with their ultimate volume once healing is complete. 
With regards to your specific question, limited fat reserves do not necessarily prohibit surgery but they do limit your results. You may want to consider implants in conjunction with limited fat transfer. Alternatively, fat transfer alone remains an option as long as you are willing to accept a more modest result.
As always, discuss your concerns with a board certified plastic surgeon (ABPS)

Thank you for your question. An in
person consultation with a board certified plastic surgeon is best for
individualized advice. At that time your body will be fully evaluated. A
surgical plan is tailored to specifically address your body. 

Ideal candidates are at a stable weight,  in good health , and have excess fat in some parts of the body and too little in other regions.  Gaining weight before the procedure is to no advantage and when you lose weight again the fat cells will shrink just like the donor site fat cells.  Typically, the transferred fat results in a significant increase in volume of the body site being treated.

Thank you for your question,It is best to seek a board certified plastic surgeon to have an in-person assessment. If a BBL is not possible, you may be a candidate for Sculptra Butt Injections. They are a legal, safe, non-surgical way of increasing buttock volume. Regards,

I have had great success with BBLs for thinner women, but these surgeries are not easy.  Maximal fat must be harvested without creating any contour deformities.  In the last few months, three of my patients weighed about 115; I was able to transfer 700 cc per buttock in each one.

I perform about 500 BBLs each year, and this procedure is the most surgeon dependent plastic surgery procedure. Find a board certified plastic surgeon with ELITE credentials (certified by the American Board of Plastic Surgery, education, training, experience)  who performs hundreds of BBLs each year. Then look at the plastic surgeon's website before and after photo galleries to get a sense of who can deliver the results. Schedule an in-office consultation with a couple of these surgeons so that they can examine you, determine the amount of fat to be transferred, and discuss your health history and ultimate goals.
Kenneth Hughes, MD, Board Certified Plastic Surgeon
Los Angeles, CA

Dear, bkelly973
Based on a bmi.23.8 you are still a candidate for surgery. if you can gain at least 5-8 more pounds it will be even  better for best results if you want a bigger booty. I would suggest you to consult a board-certified plastic surgeon. 
Dr.John Sampson, MD

Certified, Board of Plastic Surgery

The most popular procedure right now
for enhancing the butt is the Brazilian Butt Lift in which fat is taken from
other places and re-injected back into the butt. It is possible you would be able to get some
enhancement with fat grafting and lipo of the hip and back to carve out more
curve.  However, the key point for consideration is whether you have
"enough" to reach your personal goals. Consult a board certified plastic surgeon in your area
to determine if you are a good candidate. Good luck!

Thanks for the question.  Photos are required or an in office consultation to answer your questions accurately.Dr T

I think that in order to assess whether or not you have enough fat for a BBL you would have to at least post photos and better than that, be seen in person.  Best of luck.

Greetings and thank you for the question.  In general, I recommend for patients to gain some weight as there may not be enough fat to harvest in this type of situation.  In general, you should seek a consultation with a plastic surgeon to determine the best plan that is suited for you. Good luck!