With the nation's new-year dieting resolutions already beginning to fall by the waysude, now is as good a time as any to introduce a documentary series in which overweight households are taken to task by a motivational expert whose methods include quarantining television sets and taking a chainsaw to sofas. In the first of six bracing episodes, the amusingly unyielding Steve Miller barges into the home of Mike and Tarnya Cuff, the latter of whom is so large she is unable to fit into her bathtub.