Hi & Welcome.
I appreciate your concern for the mandatory screening of the diseases that is required to obtain a job visa in a middle east country like Saudi Arabia.
You need not have to worry about your
underweight, it is not included in the list of diseases that make you unfit to get a job visa.
Following diseases if found make an individual UNFIT to obtain the job visa.
AIDS,
Hepatitis B & C, TB, Leprosy, Malaria,
Filariasis, &
Syphilis.
Other diseases include:
• Chronic kidney or liver or
heart failure, known case of cancer, and psychiatric or neurlogical disease.
So, once again, there is not need to worry.
Everything will be alright Insha Allah.,
Best of luck.
A feed back is appreciated.