Hi AA,
Try the Health Promotion Board (
http://www.hpb.gov.sg), public hospitals in Singapore (
http://www.singhealth.com.sg,
http://www.nhg.com.sg) for dietician jobs. Also the Singapore Sports Council (
http://www.ssc.gov.sg) for jobs in sports nutrition. I think the Singapore General Hospital (SGH) is hiring dieticians at the moment. Do check out their website.
Since you're interested in pursuing your PhD in food and nutrition science, try the National University of Singapore (
http://www.nus.edu.sg) or Nanyang Technological University (
http://www.ntu.edu.sg). If you're looking at working and studying at the same time, eg part-time PhD, look at the Health Sciences Authority (
http://www.hsa.gov.sg).
If you're really keen in working/studying in Singapore, also try writing to lecturers at NUS, NTU and the polytechnics. Once you've contacted a few, you'll get a better idea as to what jobs are available and if these lecturers are able to take you in. Try contacting the polytechnics if you're interested in more food science technology - based research. Polytechnics may also employ you as a tutor or lecturer.
Since you have an MSc, you may also wish to look into working in private food and beverage companies in Singapore. If your performance is good, the company may even sponsor your PhD studies in Singapore with or without a bond period attached.
So really, it's up to you. I can only think of this much. If you wish, you can also post your resume up on job search websites. You can also look into joining pharmaceutical companies as a clinical research associate or sales/marketing. Good luck!
