Background Accurate assessment of dietary intake is important for planning, implementing of health promotion and when evaluating the effectiveness of public health interventions. However, measuring dietary intake is one of the most challenging aspects of public health research as no dietary method can measure dietary intake without error. Therefore, strategies that support researchers to choose the most appropriate dietary assessment method will help to strengthen research in this field. This study, undertaken for the Diet@net consortium aims to establish expert consensus on best practice guidelines (BPG) for carrying out dietary assessment in order to help non-experts in collecting dietary information.