Traditionally, nutrition research has focused on individual nutrients, and more recently dietary patterns. However, there has been relatively little focus on dietary intake at the level of a 'meal'. The purpose of the present paper was to review the literature on adults' meal patterns, including how meal patterns have previously been defined and their associations with nutrient intakes and diet quality. For this narrative literature review, a comprehensive search of electronic databases was undertaken to identify studies in adults aged ≥ 19 years that have investigated meal patterns and their association with nutrient intakes and/or diet quality. To date, different approaches have been used to define meals with little investigation of how these definitions influence the characterisation of meal patterns. This review identified thirty-four and fourteen studies that have examined associations between adults' meals patterns, nutrient intakes and diet quality, respectively. Most studies defined meals using a participant-identified approach, but varied in the additional criteria used to determine individual meals, snacks and/or eating occasions. Studies also varied in the types of meal patterns, nutrients and diet quality indicators examined. The most consistent finding was an inverse association between skipping breakfast and diet quality. No consistent association was found for other meal patterns, and little research has examined how meal timing is associated with diet quality. In conclusion, an understanding of the influence of different meal definitions on the characterisation of meal patterns will facilitate the interpretation of the existing literature, and may provide guidance on the most appropriate definitions to use. Table 1 Overview of the three meal pattern constructs, and examples of variables currently assessed in the literature and the assessment methods that have been used to collect the meal pattern data Construct Variable Operational definition(s) Example(s) of methods Patterning Frequency of EO (meals and snacks) Mean number of EO/meals/snacks per d ( 14 ) Dietary recall (24 h) ( 14 ) Weekly food diary ( 15 ) Meal patterns questionnaire ( 16 ) Single questionnaire items ( 17 ) Spacing of EO Mean time between EO ( 14 ) Dietary recall (24 h) ( 14 ) Regularity of meals Consistency of EO frequency and spacing ( 18 ) Usually eats breakfast, lunch and dinner each day ( 19 – 21 ) Semi-quantitative food records ( 18 ) Single questionnaire items ( 19 , 20 ) Food records (3 d) ( 21 ) Meal skipping Usually omits breakfast, lunch or dinner ( 17 , 22 ) Single questionnaire items ( 17 ) Meal patterns questionnaire ( 22 ) Dietary recall (24 h) ( 23 ) Meal timing The timing of breakfast, lunch or dinner (early/late) ( 24 ) Time-of-day wherein majority of daily EI is consumed (morning, midday, evening/late) ( 25 – 27 ) Late-night eating (eating after going to bed) ( 28 ) Food records (7 d) ( 24 ) Prescribed diet (intervention studies) ( 26 ) Dietary recall (24 h) ( 27 ) Single questionnaire items ( 28 ) Format Meal food type/combinations Classifications of combinations of foods in meals ( 29 ) Food records (7 d) ( 29 ) Meal food sequencing Temporal distribution of consumption of food groups and intake of energy and nutrients within a meal ( 30 ) Food records (2 d) ( 30 ) Nutrient composition Energy, protein, fat and carbohydrate composition of a meal ( 25 , 26 , 31 ) Prescribed diet (intervention studies) ( 26 ) Weekly food diary ( 31 ) Context Presence of others at a meal (for example, friends/family) Types of food eaten in different social contexts (for example, alone v. There was significant variation in the aspects of meal patterning examined and these aspects could be broadly categorised as: meals v. snacks, eating frequency, meal skipping/regularity and meal timing. These categories are used below to direct discussion on the studies' findings in relation to associations with nutrient intakes. The potential impact of different definitions on the characterisation of meal patterns and their associations with nutrient intakes is also discussed. Meals v. Meal skipping and nutrient intakes A total of six studies ( 23 , 64 , 66 , 68 , 69 , In a study of Japanese women students ( 71 ) , skipping lunch or supper was negatively correlated ( P < 0·05) with total EI and absolute intakes of carbohydrate and vitamin K (lunch only). Meal timing and nutrient intakes Only three studies were identified that examined associations between meal timing and EI ( 76 , 79 , 84 ) or macronutrient intake ( 76 ) . In these studies, the proportion of EI consumed in the evening was positively associated with overall EI ( 76 , 79 , 84 ) . Potential impact of different meal definitions on the characterisation of meal patterns and associations with nutrient intakes and diet quality Clear and objective definitions of what is a meal and what is a snack are critical for determining the energy and nutrient contributions of meals v. snacks, meal skipping or meal timing. Without a clear definition misclassification bias is likely, thus affecting the interpretation of associations with nutrients both within and across studies. In allowing participants to identify meals and snacks, subjective decision-making is inherently present. In addition the nutritional impact of snack, meal and overall eating frequency remains unclear and little research has looked at the how meal timing influences nutritional intake/overall diet quality. This may be an important area of research in light of preliminary evidence suggesting that the timing of energy and/or macronutrient intake during the day is associated with cardiometabolic risk ( 27 , 28 , 99 , 100 ) . The conflicting findings for the associations between eating frequency (including snack/meal frequency) and nutrient intake/diet quality may be, in part, attributed to not only the heterogeneity of meal patterns examined, but also to different definitions of meals and snacks.