Hello, your height is 167 cm that means your weight should be in between 65- 68 depending on your body frame. That means u need to gain weight in order achieve ideal weight.
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
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.
Next Steps
For more information and to contact me directly visit https://www.facebook.com/pg/doctorplanmydiet/about/
Thanks with regards
Dt.Ankita