There are many reason of being underweight.
1. Endocrine disturbances
2. Genetic
3. Vitamins and minerals deficiency
4. Psychological problem
5.IBS
6. Eating disorder
7.
Liver dysfunction
And many more
So my opinion is to contact directly to us so that we can find the cause of weight reduction and suggest according ly.
Next Steps
For more information and to contact me directly visit https://www.facebook.com/pg/doctorplanmydiet/about/
Thanks with regards
Dt.Ankita