You cannot stop her cholesterol medications just like that, the cholesterol levels will fluctuate then and that will have a major impact on her body.
High cholesterol could be a familial problem, need not be only because of diet.
Irrespective of the cause, do not stop her medication without consulting the doctor who had started her on the same
Next Steps
Continue her on the cholesterol medications she is on for atleast 2 months then get her
lipid profile and CBC done and follow up with her doctor with reports for dose adjustment if any
Health Tips
Avoid fried and fatty food.
As far as her weight is stable, no problem with that if it's not hampering her work.