Hello dear, surely will help you.
See,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
We treat diseases by treating the cause of disease.
So my opinion is to contact directly to us so that we can find the cause of weight reduction , gathering all your data and according ly we will suggest you.