If someone appears to be obese kick down their doors in the middle of the night and yell obscenities at them, assault their families and break up their families, put guns to their heads and threaten to kill them, drag them off to the gulags for lifetime sentences.  If they find more than one box of twinkies mandatory minimum sentences.  More money for the police, lawyers, judges, court personnel, prison, parole, medical industrial complex, and bakers.  Then we can blame another country for our obesity problems and ruin their country as well.  Just say no to fat people.
On a lighter note, really what happened is the aliens manipulated and crossed human DNA with cow DNA as they just love to eat rump roast and will soon have a feast!