Does the fat move to other areas after lipo or BBL?

Thank you very much for your
question, as it is a good one. The fat cells that are eliminated during a
liposuction procedure will not return. However, if a patient should gain weight
in the future, the surrounding fat cells can still expand. This means that
liposuction results can be long-lasting, but the aesthetic benefits of
treatment require a patient to continue with a healthy lifestyle. The fat cells
that are transferred to the buttocks during a Brazilian Butt Lift are living
tissue, and will be affected by weight fluctuations. I recommend that you
schedule a consultation with a board certified plastic surgeon, experienced in
BBL procedures. He/she can explain the procedure in detail, as well as show you
before/after photographs of recent patients, giving you a better understanding
of the liposuction and fat transfer process.

Patients will commonly wonder what the effects of liposuction will be on their weight and more specifically their ability to gain or lose weight in treated and untreated areas. 
After puberty, an individual will have the same population of fat cells for the remainder of their lives (barring an intervention). Any changes in weight will manifest not as more or less fat cells but rather swelling or shrinking of those very same fat cells.
Liposuction destroys or reduces the population of fat cells in a treated area. These cells once gone are gone for good. The treated areas now harbor a reduced population of cells and consequentially have a reduced potential for weight gain or weight loss. However, a reduced potential does not make changes in these areas absolutely impossible. The remaining cells can still swell with weight gain potentially compromising a cosmetic result.
The final component is the least understood. This is that of weight/fat distribution. It remains unclear how the body directs particular populations to change. Patients will often lament that attempts at weight loss are frustrated by losses in areas not targeted and weight gain by contrast goes directly to perceived problem areas. It is impossible to predict how a patient will respond to weight gain. While we know that treated areas must theoretically have a lower potential for growth by virtue of reduced adipocyte populations, this does not necessarily always hold true with some patients always demonstrating the effects of weight gain in the same predictable areas. Similarly, post operative weight gain is not always manifested in untreated areas.
The best advice one can give is to reach a stable healthy weight pre-operatively and try to maintain post-operatively. This is the best way to achieve a good result with the best chances for longevity.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).

The fat will not move, but gains in weight will distribute differently.Kenneth Hughes, MDLos Angeles, CA