Taking vitamins should not make a person more hungry. However, the increase in vitamins may bring a depressed appetite back to normal.
A lack of certain nutrients may cause a decrease in appetite, but starting a vitamin regimen may cause the appetite to return. Therefore, it might seem as though vitamins make the person hungrier. The nutrient deficiencies known for causing a lack of appetite are vitamins A, B and B12.
An increase in energy can also increase appetite levels. When a person starts taking a vitamin supplement, he or she might become more active.
If a person experiences a persistent increase in hunger, he or she should consult a doctor to rule out any illnesses.