Well, I would say that she did herself a great deal of damage to herself. Eating disorders especially over long periods of time, change a persons body in numerous ways. She is getting older, her metabolism is slowing down. Typically after the age of 30, there is a decline in metabolic rate that is associated with the expected 7-10% loss of muscle mass each decade after 30 in untrained individuals. Also having more mass makes a person actually more metabolically efficient at storing energy, or losing it as metabolic waste depending on your point of view.
In biological systems across nature. Organisms that have more body mass, seem to require less energy per unit of mass than that of less massive organisms. For example, pound for pound an Elephants' metabolic efficiency is much greater than that of a dog, or a human or any organism smaller than it. This is called
Kleiber's Law, and is expressed as E=M¾ Where mass is expressed in kilograms and E or energy is expressed in calories. Thus in theory it makes it harder for a heavier person to lose weight. This theory is very controversial but for 60 plus years no one has been able to disprove this theory. The numbers expressed as the power of ¾ is sometimes debated but generally holds up when talking about metabolism.
Now what does this mean to you, it means that in theory she is going to have several factors working against her to lose weight again. However the most important and incalculable factor is her will power to lose the weight and do it in a health manner. That my friend is where you come in and have to figure out how to do that. The art of figuring out how to properly educate and motivate your client to follow the science and philosophy that you know, is really the only factor that matters.
Its as simple as calories in vs calories out on paper....LOL