There's no particular reason to think she had an eating disorder, either -- at least not for some years. The reason for the "eating disorder" story is that it's about the only alibi available for the only suspect in a probable case of domestic violence.
And, please note that the bone scan reported "trauma," not bone disease. It wasn't from dieting, it was from brutal force.
The bulimic story came about because she had a low potassium level when she was admitted to the hospital. Maybe she just didn't like bananas.