You know, for all that Etta seems a bit on the pudgy side, she must have a fair amount of muscle to make up for it, because she keeps going on missions like these that require extreme athleticism - and passing them with flying colors! If she were really as fat as she's sometimes portrayed, she'd be waddling behind the others, wheezing and gasping and yelling at them to slow down. My guess is that, while Etta is certainly chubby, and usually wolfing down chocolates, she makes up for it by constantly DOING stuff. Being Wonder Woman's sidekick is the ultimate exercise regimen - you run around, climb mountains, hurdle walls, punch people in strange and exotic places, swim, fence, box - it's non-stop action! So while she's putting on weight all the time, she's losing it just as fast, which keeps her at a sort of happy medium (well, happy for HER, anyway, since she doesn't mind being plump). She's like a dwarfish female American version of a Sumo wrestler.