How important is breakfast?

INVITED COMMENTARYHow important is breakfast?It is popularly said that 'breakfast is the most important meal of the ~.i y ' ; however, like many apparently simple statements this raises questions that turn out to be rather difficult to answer.An obvious question is: important for what?It seems that the phrase usually implies some short-term benefit, such as the avoidance of hunger later in the morning, or the optimization of performance at school or work.There are, though, some anomalies here.Despite the fact that breakfast follows the longest 'fast' of the day and, therefore, would seem to be an important opportunity for 'refuelling', a significant minority of people rarely eat breakfast, and for those who do, breakfast is typically the smallest of the three 'main' meals.Is this simply because we do not leave ourselves enough time to eat before starting out on our daily routine, or is it that we are not really very hungry so soon after waking?Perhaps this is partly the origin of the phrase, to encourage more enthusiasm for a meal which collective experience has shown to be beneficial.What then are the effects of breakfast on human health and functioning?The review article by Ruxton & Kirk (1997) provides evidence for some of the nutritional benefits of breakfast.They come to the cautious conclusion that eating breakfast, particularly when this includes breakfast cereals, is 'a marker for an appropriate dietary pattern'.This is based on findings of associations of breakfast consumption with a lower percentage intake of fat, a higher percentage intake of carbohydrate, higher intakes of dietary fibre and certain micronutrients, and also lower blood cholesterol levels and lower body weight.In other words, the nutritional impact of breakfast appears to be very positive.Why, then, is any caution needed?The various findings present a mostly consistent picture, but as Ruxton & Kirk (1997) note, a vast majority of the studies they review are epidemiological (i.e.correlational) in nature.Determining the contribution of a particular meal or food to physical or mental wellbeing is a cause-and-effect question, and accordingly correlational evidence cannot give definitive answers.For example, the often-cited inverse relationship between meal frequency and body weight or body mass index may indeed be partly explained by the relatively prolonged satiating effects gained by eating at breakfast time and/or eating breakfast cereals which have a high-carbohydrate content.However, it probably also reflects the (perhaps misguided) strategy adopted by many overweight dieters who miss breakfast in an attempt to start the day as they mean to go on -that is, to eat as little as possible.Additionally, there is evidence from studies of animal models of obesity suggesting the existence of a negative feedback influence of body fat on appetite which acts primarily to reduce the tendency to initiate eating, rcsulting in decreased meal frequency (Mela & Rogers, 1997).A variety of physiological and cognitive influences may therefore underlie relationships between body weight and meal frequency and whether or not breakfast is eaten.Questions such as the efficacy of eating breakfast in promoting weight loss can only be addressed convincingly by conducting specific intervention trials.(Actually, the association of human obesity with a 'gorging' pattern of intake characterized by relatively large, infrequent meals, like the idea that energy taken later in the day is more fattening, has not been confirmed by results from the majority of recent studies; Mela & Rogers, 1997.)