Definitely it is a truth, after liposuction or tummy tuck, fat deposits differently: it will go other places where there is not scar tissue and those areas will be upper back (buffalo hump), upper chest, shoulders, arms, neck, face, intra-abdominal cavity etc exactly those areas where are...
I don't really see the advantage of gaining weight to enhance the benefits of liposuction. If excess fat exists at your present weight That would be improved by liposuction I see no reason not to proceed.
Swelling and fluid retention always happens after liposucton and a weigh gain of 10 pounds is not unusual However, swelling of one leg is an symptom that you need to tell your doctor about - you should call your surgeon.