UnitedHealth Group Inc. has sued two brothers who ran a company that promoted Lap-Band weight-loss surgery, accusing the pair of defrauding the insurer of more than $40 million through a complex billing scheme. The Los Angeles Times reports Thursday that the suit claims the network of surgery centers run by Michael and Julian Omidi tricked the insurer into paying claims for medical procedures that were unnecessary, ineligible for coverage or never even performed.