Whenever I see the term starvation mode come up ... the hair on the back of neck stands up. However, this may be one of the closest examples of true starvation mode that we'll see. The actual slowing of a persons metabolism.
But, I don't feel that this began because of a low caloric intake.
I'm going to assume a couple of things. Although, I think Angel did say this person was older ??? She probably never went to the gym and probably had a less than perfect diet.
OK ... we use calories two ways.
One is by activity. If you increase your metabolism, you use more calories right? We exercise on top of all the things we already do. This woman not only can't exercise, nor can she do the everyday things she used to. Resulting in a lower daily caloric requirement.
We also use calories just to run the machine. Regenerate new tissue, make lungs move, make heart beat etc. When we are quieter than normal, these things use less calories too. You breath more shallowly while you are asleep, your pulse in slower, right? Circulation can become impaired. Even healing is slower.
Along with this comes muscle atrophy. If you don't move it you lose it, right? Muscle mass uses more calories than fat mass. Inactivity and poor nutrition can cause a withering, of sorts, of muscle tissue ... again lowering our caloric needs.
And all of this can make you tired so you get even slower.
I feel that this woman is suffering from this. In theory then, good quality food and any kind of activity should help.
So, I've had my little rant.
Eat good food. Move yourself. Lift something.