Hi ma'am,
The ideal weight is calculated only as per height. However as per age, she would require to know about her total body fat percentage.
As per 5'1" (154.94cm) the ideal weight should be around 48-50 kgs to fall under an Ideal Body Mass Index.
It is suggested that this weight is composed of lesser fat % & higher muscle %. This would help her stay fit & healthy ; because at 53 years, she is likely to face muscle breakdown (naturally). This might make her feel weak & lethargic overall even if her weight is fine.
Next Steps
Getting a body composition done is an easier way to analyse her health status, rather than just calculating height: weight ratio.
You can get in touch with us for more information.
Health Tips
Please note that weight is also affected by existing medical conditions.