Hiii Jayshree,
You can take admission in Lady Irwin college or Institute of home economics to fulfill your dream of becoming a dietcien. You have to take admission in the home science course. The course offers 5 major field namely Food and nutrition, human development, resource management, development communication and extension and fabric and apparel. To become a dietician, you have to score really good in 1st three semesters of college. According to your aggregate you will be given the subject. If you score really good you will , according to the availability of the seat, be given food and nutrition which will help you to become dietcien in future.
Both the colleges started above comes under Delhi university and you have to register yourself in it.
I am also a student of home science hons in Lady Irwin college.
I hope this answer will help.
All the best for your future!!

Hi jaysree.
https://gmch.gov.in/dietetics/dietetics.htm
This link have the details about your aspiring course.
This college is of government.
Having the details about the entrances.
This help you.
And hope you get your answer from  this