In 2009-10 the Dietitians Association of Australia conducted a series of systematic reviews for the National Health and Medical Research Council to generate evidence statements to inform the revision of the Dietary Guidelines for Australians. In total 202 body of evidence statements were constructed and assigned a grading detailing the certainty with which each could be used to inform policy. This paper describes some of the challenges and insights gained from the process, specifically related to: study type, study quality assessment, the lack of quantified data, diet exposure, definition of a healthy population, generalisability and applicability, and resource allocation. It is clear that there is still a need for further refinement of the methods for evaluating evidence for nutrition policy, but the current dietary guidelines are now much more robustly evidence informed than ever before.