PARKLAND, Fla. — Jean Nidetch ambles down the hallway of the senior community where she lives, two cups of Coca-Cola teetering on her walker. In her one-bedroom apartment, there are Klondike bars in the freezer and, in the fridge, Baileys Irish Cream beside Chinese take-out. If these don’t seem the trappings of the woman who founded Weight Watchers, don’t be alarmed. At 87, Nidetch has earned some allowances. Besides, she says, she doesn’t touch most of the stuff anyway.