As the DAA regulates dietitians within Australia, you would likely have to study Dietetics with an accredited University course to become accredited with them. Becoming a qualified dietitian in Australia typically means 3-4 years of full-time study and upwards of ~$50,000 in course fees!
MNU on the other hand qualifies students with a regulated Level 5 Diploma in Advanced Nutrition Science in just 13 months. As an MNU Certified Nutritionist, graduates can also gain insurance in Australia to work with a wide variety of clients on their health, body composition & performance-related goals.
For more information on potential career opportunities and services you can offer as an MNU Certified Nutritionist, you can read: Can this course help me have a career in nutrition? and What services can I offer after I graduate?