As you.have this issue of no appetite,it truly reveals defeciency particularly B vitamins
So check with a physician for appropriate tests to correct deficiencies and other parameters if found to be deficient
A customized diet plan can be suggested based on your deficiency status
Kindly do the needful
Next Steps
Include small meals at frequent intervals
Include variety of protein rich foods such as sprouts,lentils beans,peas ,milk & Dairy on a everyday basis along with energy dense foods such as sufficient carbohydrates from cereals,vegetables,fruits which also adds fibre in your diet to increase absorption of B vitamins as well.