Science

Pros of government college over equally good private alternative:
Fees: Incredibly low fees. You save a huge chunk of money. You get rid of unnecessary student loan and ROI (Return-on-Investment) is high. Also, there is likely to be better economic diversity among students which might help in learning some essential life lessons.
Reservation: If you belong to the reserved background, you already know the obvious advantages which come along. And if you're from general category probably you don't need to compete hard with rest 50% of the under the talented bunch of reserved category students.
Industry perception: There are quite a few companies especially engineering service based ones who still think that a government college (no matter what) is supposed to be better than it's equivalent private one. In this regard, a government college might be preferred ahead of your private counterparts all though this applies for only a few chipmunk companies.
Student culture: This is subjective but on many occasions, it's observed students of government colleges tend to be more academically oriented than their equivalent private counterparts. The collective socioeconomic background might be a factor playing a role in this. All though this can never be generalized.
Career: A decently branded government college might give you a slightly better career launch. Suppose you're choosing a remote NIT over an equally good private alternative, Thapar or Manipal & just by the NIT brand you can possibly gain an edge in getting some extra few opportunities in either of industry or get admitted in foreign universities.

As far as I know, there is no part time IIT JAM. You will have to devote yourself to the exam if you want to secure a passing grade in the exam and qualify for M.Tech or M.Sc.
JAM 2018 eligibility criteria:
The common criteria across institutes for each programme are:
JAM eligibility criteria is common for each program across institutes for appearing in the postgraduate science admission test.
The candidates should have secured at least 55% in subjects including languages and subsidiaries of all the years combined. Those, however, belonging to SC/ST and OBC categories need to secure at least 50 percent marks in the subjects.
Candidates need to note that equivalence of marks in case of grades in letter/CGPA (and not in percentage of marks) will be decided by the participating institutes of JAM.
As per the JAM eligibility criteria 2018, candidates will need to submit their proof of qualifying degree examinations by September 30th, 2018 to the admitting institute. However, upon failing to do so will lead to cancellation of their candidature.

Further studies:
Valid Diploma certificate holders may pursue relevant Bachelor's degree course. B.Sc degree can then be followed up with PG degree or PG Diploma courses.
Graduates have a handful of PG courses to choose from. M.Sc and PG Diploma courses can be used to specialize in disciplines such as:
Clinical Nutrition
Paediatric Nutrition
Public Health Nutrition
Food Science/Technology
Sports Nutrition/Dietetics
Gerontological Nutrition
Renal Nutrition
Diverse job opportunities exist in front of nutritionists and dieticians in India. Both Government and private sector job opportunities are available in front of them.
Talking about Government sector, some of the well known recruiters include:
Government hospitals
Community health centres
Government Schemes and Missions (ICDS, NHRM, etc.)
Government Organizations (FNB, ICMR, Public Health Foundation, etc.)
Government R&D units
Government nursing homes
Government Nutrition Education Institutes
Coming to the private sector, some of the well known recruiters include:
Private clinics and hospitals
Nursing homes
NGOs
Food products manufacturing firms
Pharmaceutical firms
Private R&D units
Private Nutrition Education Institutes
Health clubs
Fitness centres
Sports centres and franchises
Hotels