OBJECTIVE To examine the association of food insufficiency with dietary intake and eating and health behaviours. DESIGN A cross-sectional study. SETTING Data were obtained from a secondary source, the Fifth Korea National Health and Nutrition Examination Survey (2010-2012). SUBJECTS The sample size consisted of 15 603 adults over 19 years of age (8898 households). RESULTS Significant differences in socio-economic factors were observed according to food insufficiency level (P<0·05), but BMI was similar among groups. Regarding macronutrients, lower protein intake and higher carbohydrate intake were found in the severely food-insufficient group, but we found no association with fat intake. Regarding micronutrients, Ca, Fe, vitamin A, thiamin, riboflavin niacin and vitamin C intakes were negatively associated with food insufficiency level (P trend<0·05). Consumption of different food groups, such as meat, fish, eggs and beans, vegetables and fruits, was significantly lower as food insufficiency level decreased after controlling for all possible variables; food group consumption also differed by sex. Overall eating and health behaviours were poorer in the mildly and severely food-insufficient groups, who received more food assistance but less nutritional education. CONCLUSIONS Our results showed that dietary intake as well as eating and health behaviours are adversely associated with food insufficiency. These findings suggest that specific strategies to help food-insufficient individuals should be developed in order to improve their dietary quality and health status.