Thank you very much for sharing your concerns with us.
For safety reasons, to be a good candidate for those procedures you want at the same time, your labs and cardiovascular preoperative evaluation must be optimal.
Therefore, you must be a healthy person, within an appropriate BMI and no history of diseases that increase the surgical / anesthetic risk degree.
Finally, I recommend you a skilled certified plastic surgeon in body contouring surgery and experienced in cases like yours where the planned operating time is less than five hours.
Dr. Emmanuel Mallol Cotes.-
You are a very good candidate for the procedures you mentioned as long as you are in good medical condition without risk factors for medical complications. Thorough preoperative evaluation, preparation and execution are imperative for good, safe outcomes with combined procedures. You have enough fat for a good BBL result. Weight gain before surgery would give you more fat, but likely detract from your tummy tuck result by adding to your intra-abdominal fat. Most surgeons recommend getting your ideal weight before surgery, not gaining weight. Consider consulting with a board certified Plastic Surgeon with experience performing combined procedures. Best wishes.
Based on your photos, you have ample fat available for BBL and I would not recommend further weight gain. That is alot of surgery you are considering so please make sure you have a board certified surgeon and anesthesiologist. It will be a difficult recovery period so plan for 1-2weeks of questioning your decision to do it all. Best wishes.
I do not routinely suggest to patients to gain weight for a BBL, because most will want to get back down to their earlier weight and potentially will lose volume in their buttocks as well.