I've also talked about her love of fad diets which she imposes on her family in the belief that if she's not tempted to eat the food she's convinced is going to make her faaaaaaaaaaaat and uuuuuuuuuugly, she won't overindulge; given that she's usually at someone else's house gorging on something because outside calories don't count, this never really works.
Neither does trying to impose any sort of exercise regime on her. This is because her hummingbird-like attention span wars against the discipline needed to stick to it and, well, to be quite honest, she made the mistake of thinking that she could just dive into aerobics without pacing herself. Her body rebelled against a sudden shift from the sedentary life she was living to full activity and, since she's not very bright, assumed that she was taxing herself to her limits. This means that we're in for a lifetime of her thinking that jogging down to a doughnut shop to swallow down fried batter makes her physically fit.