Effect of breakfast on subjective appetite

It is generally believed that omission of breakfast will increase appetite, causing overeating at subsequent meals, resulting in weight gain⁽ Reference Pereira, Erickson and McKee ^{21 )}. In research, visual analogue scales have been used to assess appetite sensations, such as hunger and fullness, and can provide a reproducible and reliable assessment of subjective appetite⁽ Reference Flint, Raben and Blundell ^{22 )}. As would be expected, a well-established pattern of appetite suppression has been observed during the morning when breakfast is consumed, compared with when breakfast is omitted⁽ Reference Astbury, Taylor and Macdonald ^{23 –} Reference Reeves, Huber and Halsey ^{31 )}. However, it is interesting to note that the subjective appetite response to subsequent meals appears to be unaffected by prior omission of breakfast, suggesting that consumption of breakfast only provides a transient suppression of appetite⁽ Reference Astbury, Taylor and Macdonald ^{23 ,} Reference Levitsky and Pacanowski ^{24 ,} Reference Chowdhury, Richardson and Tsintzas ^{26 –} Reference Clayton, Stensel and James ^{29 )}. This was recently investigated in two studies that were designed to determine how 24 h subjective appetite profiles responded to breakfast consumption or omission, with ad libitum ⁽ Reference Clayton, Barutcu and Machin ^{28 )} or standardised⁽ Reference Clayton, Stensel and James ^{29 )} lunch and dinner meals. In these studies, breakfast (25 % estimated energy requirements) was consumed at 08·00 hours, with lunch and dinner meals consumed at 12·30 and 18·00–19·00 hours. These studies found a reduction in appetite throughout the morning when breakfast was consumed compared with when breakfast was omitted. However, the consumption of an ad libitum lunch meal offset appetite to the same extent, independent of breakfast consumption, and this effect persisted throughout the remainder of the day. The same response was observed when standardised lunch (35 % estimated energy requirements) and dinner (40 % estimated energy requirements) meals were provided, consequently preserving the energy deficit created by breakfast omission. Similar studies have also observed a transient suppression of appetite after breakfast consumption in both lean⁽ Reference Levitsky and Pacanowski ^{24 ,} Reference Chowdhury, Richardson and Tsintzas ^{26 )} and obese⁽ Reference Chowdhury, Richardson and Tsintzas ^{27 )} subjects, with subjective appetite appearing to be offset independent of breakfast consumption, after an ad libitum lunch meal. Results from these studies demonstrate an imprecise regulation of subjective appetite in response to an energy deficit. However, it should be noted that subjective appetite sensations do not always predict subsequent energy intake⁽ Reference Clayton, Stensel and Watson ^{32 ,} Reference James, Funnell and Milner ^{33 )}.

Effect of breakfast on peripheral appetite hormones

Part of the regulation of appetite may involve several gut peptides, including the appetite stimulatory hormone ghrelin and hormones associated with satiation and satiety, such as peptide YY (PYY), glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide, cholecystokinin and leptin. Understanding the response of these hormones to energy balance fluctuations may provide valuable information about whether dietary interventions (such as breakfast omission) will be tolerable outside of the laboratory environment. Astbury et al. ⁽ Reference Astbury, Taylor and Macdonald ^{23 )} found that anorexigenic hormones (GLP-1; PYY) were greater up to 30 min after consumption of a 1050 kJ liquid meal 2·5 h after breakfast consumption, compared with after breakfast omission. However, no differences in the orexigenic hormone ghrelin were observed. Additionally, breakfast omission caused an increase in glucose and insulin response to the liquid meal, compared with breakfast consumption. This dampened glycaemic response to the second meal of the day, is known as the ‘second meal effect’ which may be related to glycogen storage⁽ Reference Jovanovic, Leverton and Solanky ^{34 )}. Gonzalez et al. ⁽ Reference Gonzalez, Veasey and Rumbold ^{25 )} similarly found a tendency for an increased glucose and insulin response to a 1500 kJ liquid meal consumed 3 h after omission, compared with consumption of breakfast, although active GLP-1 concentrations were not different between trials. The different GLP-1 findings may be due to whether total⁽ Reference Astbury, Taylor and Macdonald ^{23 )} or active GLP-1⁽ Reference Gonzalez, Veasey and Rumbold ^{25 )} was measured. Additionally, Thomas et al. ⁽ Reference Thomas, Higgins and Bessesen ^{30 )} examined whether habitual breakfast patterns influence the hormonal regulation of appetite, in response to a standard lunch consumed 4 h after breakfast consumption/omission. Ghrelin concentrations were not affected by the omission or consumption of breakfast, but elevated concentrations of PYY and GLP-1 were reported. Additionally, this study found that the glycaemic response to a standardised lunch was attenuated in habitual breakfast omitters, suggesting some metabolic adaptation may occur over time. In a similar study, Clayton et al. ⁽ Reference Clayton, Stensel and James ^{29 )} found no difference in acylated ghrelin or GLP-1 concentrations either 1·5 or 3·5 h after a standardised lunch. Collectively, these studies suggest breakfast minimally affects the orexigenic appetite hormone ghrelin, with some evidence that breakfast may increases anorexigenic hormone profiles, in response to subsequent standardised feeding. However, breakfast omission may affect eating behaviour, and the provision of standardised meals does not allow for appetite hormone profiles to be assessed under these circumstances.

This was investigated as part of the Bath Breakfast Project⁽ Reference Betts, Thompson and Richardson ^{35 )}. In these studies, the glycaemic, orexigenic and anorexigenic hormonal responses 3 h after breakfast consumption/omission and 3 h after an ad libitum lunch were determined in both lean⁽ Reference Chowdhury, Richardson and Tsintzas ^{26 )} and obese⁽ Reference Chowdhury, Richardson and Tsintzas ^{27 )} subjects. Consumption of breakfast suppressed acylated ghrelin, with concomitant increases in PYY, GLP-1, insulin and glucose, compared with breakfast omission, in both lean⁽ Reference Chowdhury, Richardson and Tsintzas ^{26 )} and obese⁽ Reference Chowdhury, Richardson and Tsintzas ^{27 )}. After an ad libitum lunch, elevated concentrations of PYY were maintained although no differences in GLP-1 (measured in lean group only) were observed. Paradoxically, acylated ghrelin concentrations were greater in the breakfast consumption trial after lunch in both the lean and obese groups. Similar responses have been reported in another study, with breakfast consumption in the morning appearing to have no effect on acylated ghrelin or GLP-1, 4 h after an ad libitum lunch⁽ Reference Clayton, Barutcu and Machin ^{28 )}.

Further research is required before definitive conclusions can be made regarding the effects of breakfast on the hormonal regulation of appetite. Current research suggests that hormonal markers of appetite are transiently suppressed by breakfast, but differences between breakfast omission/consumption appear to be diminished following lunch, which is in line with subjective appetite sensations. This results in similar hormone concentrations in the afternoon, independent of breakfast consumption. However, there is some evidence of a prolonged anorexigenic response to breakfast, particularly with PYY. Further research is required to determine the long-term effect of breakfast on the hormonal regulation of appetite. This has been partly addressed, with one study finding impaired post-prandial insulin sensitivity after 2 weeks of breakfast omission⁽ Reference Farshchi, Taylor and Macdonald ^{36 )} and another finding no change in fasted insulin sensitivity as well as no difference in fasted acylated ghrelin, PYY, GLP-1 or leptin after 6 weeks of either consuming or omitting breakfast⁽ Reference Betts, Richardson and Chowdhury ^{37 )}.

Effect of breakfast on ad libitum energy intake

Single exposure studies

The association of regular breakfast omission with a higher BMI⁽ Reference Cho, Dietrich and Brown ^{7 ,} Reference Purslow, Sandhu and Forouhi ^{8 )} has led to the widespread belief that breakfast omission causes overeating at subsequent meals and greater daily energy intake⁽ Reference Pereira, Erickson and McKee ^{21 )}. However, the weight of evidence from well-controlled laboratory intervention studies (Table 1) does not support this belief⁽ Reference Levitsky and Pacanowski ^{24 –} Reference Clayton, Barutcu and Machin ^{28 ,} Reference Hubert, King and Blundell ^{38 )}. The majority of single exposure studies have reported either no difference⁽ Reference Levitsky and Pacanowski ^{24 ,} Reference Gonzalez, Veasey and Rumbold ^{25 ,} Reference Chowdhury, Richardson and Tsintzas ^{27 )}, or an increase⁽ Reference Astbury, Taylor and Macdonald ^{23 ,} Reference Levitsky and Pacanowski ^{24 ,} Reference Chowdhury, Richardson and Tsintzas ^{26 ,} Reference Clayton, Barutcu and Machin ^{28 ,} Reference Hubert, King and Blundell ^{38 )} in energy intake, at the first meal consumed after breakfast (i.e. lunch). However, with the exception of one study⁽ Reference Astbury, Taylor and Macdonald ^{23 )} the increase in energy intake at lunch was not sufficient to fully compensate for the energy omitted at breakfast, resulting in a reduced gross energy intake (i.e. breakfast + lunch energy intake)⁽ Reference Levitsky and Pacanowski ^{24 –} Reference Clayton, Barutcu and Machin ^{28 ,} Reference Hubert, King and Blundell ^{38 )}. With the exception of Astbury et al. ⁽ Reference Astbury, Taylor and Macdonald ^{23 )}, who reported 78 % compensation at lunch for the energy omitted at breakfast, studies have generally reported compensation in the range 0–35 %⁽ Reference Levitsky and Pacanowski ^{24 –} Reference Clayton, Barutcu and Machin ^{28 ,} Reference Hubert, King and Blundell ^{38 )}. The amount of compensation observed at lunch might, in part, be related to the energy content of the breakfast supplied. Consuming a low-energy breakfast has been shown to be more accurately compensated for at subsequent meals⁽ Reference Schusdziarra, Hausmann and Wittke ^{39 )} and might explain why Astbury et al.⁽ Reference Astbury, Taylor and Macdonald ^{23 )} observed almost complete compensation, whilst others reported much less compensation⁽ Reference Levitsky and Pacanowski ^{24 –} Reference Clayton, Barutcu and Machin ^{28 ,} Reference Hubert, King and Blundell ^{38 )}. Whilst it may be possible to increase food intake to compensate for a small energy deficit, a certain threshold may exist, above which complete energetic compensation at a subsequent meal (or meals) is unlikely.

Table 1. Intervention studies assessing energy intake after a single breakfast omission

Where available, energy intake at breakfast is presented as mean (sd). Otherwise, mean or absolute intake is presented, as appropriate.

BO, breakfast omission; BC, breakfast consumption; EI, energy intake; AL, ad libitum; CHO, carbohydrate.

* This study compared a very small with a large breakfast, rather than the complete omission of breakfast.

Two studies⁽ Reference Levitsky and Pacanowski ^{24 ,} Reference Clayton, Barutcu and Machin ^{28 )} also assessed energy intake beyond a single meal (Table 1). Consistent with other findings, an increase in energy intake was observed at lunch following the omission of breakfast. Both studies also found no additional energetic compensation occurred at subsequent eating occasions, and therefore gross energy intake (including breakfast) was reduced by 1885⁽ Reference Levitsky and Pacanowski ^{24 )} and 2740 kJ⁽ Reference Clayton, Barutcu and Machin ^{28 )} following breakfast omission. Similarly, Thomas et al. ⁽ Reference Thomas, Higgins and Bessesen ^{30 )} also reported no difference in energy intake at an ad libitum dinner, provided 5 h after a standardised lunch, independent of breakfast consumption in the morning. In this study, gross energy intake was reduced by approximately 710 kJ when breakfast was omitted, but this did not reach statistical significance. Collectively, these studies suggest that energy intake is not accurately regulated in the short term⁽ Reference Levitsky ^{40 )}, and that omission of a single breakfast meal is unlikely to lead to compensation later in the day.

Multiple exposure studies

In a descriptive study, Schusdziarra et al. ⁽ Reference Schusdziarra, Hausmann and Wittke ^{39 )} measured energy intake of 380 subjects over 10 d, finding that daily energy intake was associated with the amount of energy consumed at breakfast. Specifically, lower energy intake at breakfast was indicative of a reduced daily energy intake. A number of intervention studies have investigated breakfast omission over longer periods of time, often using food records to estimate daily energy intake (Table 2). Whilst the results of these studies are slightly more varied, once again the weight of evidence suggests that omission of breakfast in the morning will reduce daily energy intake in the longer term⁽ Reference Martin, Normand and Sothier ^{14 ,} Reference Betts, Richardson and Chowdhury ^{37 ,} Reference Reeves, Huber and Halsey ^{41 )}. In one of these studies, a reduction in energy intake was observed in a 6 week between groups breakfast intervention study. Subjects were instructed to consume ⩾2930 kJ before 11·00 hours, or abstain from food completely until 12·00 hours. Timing, type and quantity of foods ingested after 12·00 hours were unaffected by consumption or omission of breakfast in the morning, resulting in a reduced energy intake of approximately 2300 kJ/d when breakfast was omitted⁽ Reference Betts, Richardson and Chowdhury ^{37 )}.

Table 2. Intervention studies assessing energy intake after multiple breakfast omissions

Where available, energy intake at breakfast is presented as mean (sd). Otherwise, mean or absolute intake is presented, as appropriate.

BO, breakfast omission; BC, breakfast consumption; EI, energy intake; AL, ad libitum.

* This study compared a very small with a large breakfast, rather than the complete omission of breakfast.

In contrast to this, Halsey et al. ⁽ Reference Halsey, Huber and Low ^{42 )} found no difference in daily energy intake, independent of consumption or omission of an ad libitum breakfast. In a study designed primarily to investigate glycaemic control, Farshchi et al. ⁽ Reference Farshchi, Taylor and Macdonald ^{36 )} found that daily energy intake was increased during 2 weeks of breakfast omission, compared to breakfast consumption. In this study, the authors balanced energy intake in both conditions by providing cereal and milk at a traditional breakfast time (07·00–08·00 hours; breakfast consumption) or later in the day (12·30 hours; breakfast omission). A chocolate-covered cookie was also consumed at 10·30 hours on both trials, and therefore subjects only fasted about 2·5 h longer during the breakfast omission period. The study was designed this way to determine whether the timing of food intake influenced glycaemic control and energy intake, independent of the amount of energy consumed. The experimental design may at least partially explain why the results of this study differ from the majority of the literature.

Surprisingly, there is a sparsity of studies that have investigated breakfast omission in overweight or obese individuals. One study investigated whether daily meal pattern would affect energy intake in obese subjects. Meals were provided as either six meals daily (constituting 4200 kJ) or, four meals daily (constituting 2800 kJ), with the two remaining meals omitted during the morning requiring subjects to fast until 12·00 hours. In addition to the provided meals, subjects were permitted to eat ad libitum after 13·00 hours. This study found a non-significant reduction (approximately 960 kJ) in daily energy intake when meals were provided as four meals daily⁽ Reference Taylor and Garrow ^{43 )}. Reeves et al. ⁽ Reference Reeves, Huber and Halsey ^{41 )} reported that during 1 week of breakfast omission, energy intake was increased between 12·00 and 18·00 hours in lean subjects and between 12·00 and 21·00 hours in overweight subjects, compared with during 1 week of breakfast consumption. Furthermore, habitual breakfast omitters consumed more after 21·00 hours than habitual breakfast consumers. Despite differing eating patterns, absolute energy intake was reduced by approximately 670 kJ/d during breakfast omission compared with breakfast consumption.

Although not directly assessing energy intake, three further studies assessed the impact of breakfast on weight loss in overweight and obese subjects⁽ Reference Geliebter, Astbury and Aviram-Friedman ^{44 ,} Reference Schlundt, Hill and Sbrocco ^{45 )}. Schlundt et al. ⁽ Reference Schlundt, Hill and Sbrocco ^{45 )} investigated a prescribed energy restricted diet in two groups, with equal energy provisions provided in either two (breakfast omission) or three (breakfast consumption) meals daily. Whilst subjects in both groups lost weight, no difference in weight loss was observed between groups after 12 weeks. The authors also stratified subjects according to their habitual breakfast habits, and found that subjects who changed their breakfast habits lost more weight than those who maintained their breakfast habits. This suggests that the success of a dietary regime might be governed, in part, by the degree in which that regime differs to an individual's normal dietary behaviour. However, this study involved a degree of dietary restriction beyond the consumption or omission of breakfast in the morning, and as such may not reflect true alterations in eating behaviour. Dhurandhar et al. ⁽ Reference Dhurandhar, Dawson and Alcorn ^{46 )} investigated the effect of recommendations to consume or omit breakfast, in free-living adults attempting to lose weight. Subjects (n 283) were randomly assigned to either consume or omit breakfast for 16 weeks, and results were compared with a control group. Although subjects in this study were attempting to lose weight, in contrast to Schlundt et al. ⁽ Reference Schlundt, Hill and Sbrocco ^{45 )} this study did not impose any dietary restraint on subjects after 11·00 hours. Results found that either consuming or omitting breakfast did NS affect weight change over a 16 week period⁽ Reference Dhurandhar, Dawson and Alcorn ^{46 )}. In another study, Geliebter et al. ⁽ Reference Geliebter, Astbury and Aviram-Friedman ^{44 )} found that 4 weeks consuming water in the morning (i.e. breakfast omission) reduced body weight to a greater extent than when 1470 kJ high- or low-fibre breakfasts were consumed.

Overall, these findings do not support the notion that omission of breakfast causes overeating at subsequent meals. Indeed several studies have found that energy intake is not sufficiently increased to compensate for omission of breakfast in the morning, therefore at least partially preserving the energy deficit achieved by breakfast omission.

Effect of breakfast on energy expenditure

It is interesting to note that some of the aforementioned longer term breakfast intervention studies have failed to observe a reduction in body weight⁽ Reference Betts, Richardson and Chowdhury ^{37 ,} Reference Schlundt, Hill and Sbrocco ^{45 )}, despite observing reductions in energy intake when breakfast is omitted. This may be due to underreporting of energy intake as opposed to a genuine reduction⁽ Reference Livingstone, Prentice and Strain ^{20 )}, but also could suggest an interaction between breakfast and energy expenditure. The intake of food in the morning will inevitably increase morning energy expenditure due to an increase in dietary-induced thermogenesis⁽ Reference Westerterp ^{47 )}. Consumption of breakfast has been shown to increase RMR during the morning, compared with when no breakfast was provided⁽ Reference Martin, Normand and Sothier ^{14 ,} Reference Clayton, Stensel and James ^{29 ,} Reference Thomas, Higgins and Bessesen ^{30 )}. Beyond lunch, breakfast does not appear to affect RMR, whether the energy deficit from breakfast omission is recovered at subsequent meals⁽ Reference Kobayashi, Ogata and Omi ^{48 )} or if the energy deficit is sustained by matching energy intake at lunch across trials⁽ Reference Clayton, Stensel and James ^{29 ,} Reference Thomas, Higgins and Bessesen ^{30 )}. Typically, daily energy expenditure has been assessed using a calorimetry chamber⁽ Reference Taylor and Garrow ^{43 ,} Reference Kobayashi, Ogata and Omi ^{48 )} or indirect calorimetry⁽ Reference Martin, Normand and Sothier ^{14 ,} Reference Clayton, Stensel and James ^{29 ,} Reference Thomas, Higgins and Bessesen ^{30 )}. However, the most malleable component of energy expenditure, physical activity, may be underestimated from these studies, as confined testing spaces and experimental control is likely to restrict free-living physical activity.

Wyatt et al. ⁽ Reference Wyatt, Grunwald and Mosca ^{16 )} administered physical activity questionnaires during a cross-sectional study, and reported an association between breakfast consumption and greater physical activity. However, there are very few studies that have directly investigated the effect of breakfast on physical activity, particularly in adults. Two studies used pedometers to estimate free-living physical activity and found no difference after 1 week of breakfast consumption or omission⁽ Reference Reeves, Huber and Halsey ^{31 ,} Reference Halsey, Huber and Low ^{42 )}. Stote et al. ⁽ Reference Stote, Baer and Spears ^{49 )} used accelerometers to estimate physical activity, and similarly found no difference when food was provided as one evening meal or three (breakfast/lunch/dinner) meals daily. Verboeket-van der Venne et al. ⁽ Reference Verboeket-van de Venne, Westerterp and Kester ^{50 )} used doubly labelled water to determine energy expenditure, and also found no difference in AEE when energy was provided in two or seven meals daily. Whilst these studies provide some information about free-living physical activity, the methodology employed in the studies limits their interpretation or makes it difficult to apply the findings directly to breakfast habits. The measurement tools used in some of these studies⁽ Reference Reeves, Huber and Halsey ^{31 ,} Reference Halsey, Huber and Low ^{42 ,} Reference Stote, Baer and Spears ^{49 )} may lack reliability and sensitivity when applied to free-living environments⁽ Reference Corder, Ekelund and Steele ^{51 )} or these studies have assessed daily meal patterns⁽ Reference Stote, Baer and Spears ^{49 ,} Reference Verboeket-van de Venne, Westerterp and Kester ^{50 )}, as opposed to the consumption or omission of breakfast.

Recently, the first data suggesting that breakfast consumption in the morning may have a causal effect on AEE in adults was reported⁽ Reference Betts, Richardson and Chowdhury ^{37 )}. Using a combined heart rate and accelerometer device, this study found a reduction in AEE, attributable primarily to a decline in light intensity physical activity, during 6 weeks of breakfast omission compared with breakfast consumption⁽ Reference Betts, Richardson and Chowdhury ^{37 )}. Whilst this reduction in AEE (1885 kJ/d) was not sufficient to fully offset the decrease in energy intake (2300 kJ/d), this study does demonstrate that appreciation of both energy intake and energy expenditure is essential to fully understand the implications of breakfast omission on energy balance. No detectable changes in body weight were observed between groups over the 6 week intervention period, and therefore future studies should look to extend this monitoring period, to determine whether any further behavioural changes occur.

Effect of breakfast on exercise performance

It has been reported that weight loss interventions that combine both dietary restriction and exercise are more successful in the long term⁽ Reference Franz, VanWormer and Crain ^{15 )}. Therefore, it is important to consider the effect that a given dietary intervention, such as breakfast omission, has on the capability and desire to perform exercise. Traditional western breakfasts tend to be high in carbohydrate, and previous studies have observed that omission of breakfast alters dietary profiles, primarily through a reduction in daily carbohydrate intake⁽ Reference Deshmukh-Taskar, Nicklas and O'Neil ^{52 ,} Reference Shriver, Betts and Wollenberg ^{53 )}. Therefore, it appears that breakfast could play a crucial role in meeting daily carbohydrate requirements and thus maximising carbohydrate availability⁽ Reference Williams and Lamb ^{54 )}. Whilst individuals concerned purely with weight management may not be overly concerned about carbohydrate availability, consuming adequate carbohydrate is of primary importance to individuals wanting to maximise athletic performance⁽ Reference Cermak and Van Loon ^{55 ,} Reference Ormsbee, Bach and Baur ^{56 )}.

Several studies have demonstrated that consumption of carbohydrate in the morning can improve exercise performance compared with performing exercise in the overnight fasted state⁽ Reference Neufer, Costill and Flynn ^{57 –} Reference Chryssanthopoulos, Williams and Nowitz ^{63 )}. However, the majority of these studies provided carbohydrate drinks rather than a typical breakfast meal, and therefore may not accurately represent breakfast consumption and omission per se. Chryssanthopoulos et al. ⁽ Reference Chryssanthopoulos, Williams and Nowitz ^{63 )} demonstrated that consumption of a high-carbohydrate breakfast meal 3 h before exercise, increased exercise capacity by approximately 9 % compared with when no breakfast was provided. This would likely be due to the effect of an overnight fast on glycogen stores. An overnight fast results in a substantial (approximately 40 %) reduction in liver glycogen⁽ Reference Nilsson and Hultman ^{64 )}, therefore decreasing endogenous glucose availability. Consumption of a high-carbohydrate breakfast will replenish liver glycogen content⁽ Reference Hawley and Burke ^{65 )}, and has also been shown to increase muscle glycogen concentrations by 11–17 %⁽ Reference Chryssanthopoulos, Williams and Nowitz ^{66 ,} Reference Wee, Williams and Tsintzas ^{67 )}. Therefore, the omission of breakfast may limit glycogen availability for muscle metabolism, and potentially reduce exercise performance⁽ Reference Coyle and Coggan ^{68 )}.

This evidence would suggest that individuals performing exercise in the morning should aim to consume breakfast between 1 and 4 h before exercise in order to avoid any decrements in exercise performance. However, it has been reported that exercise in the evening may be more acceptable and tolerable than exercise in the morning⁽ Reference Maraki, Tsofliou and Pitsiladis ^{69 )}, suggesting that this may be a more preferable time to exercise for those exercising for weight management. Therefore, it would be of interest to determine whether the detrimental effect of breakfast omission on exercise performance is exclusive to the morning, or whether these effects continue throughout the day. This has been determined in one study, in which breakfast was provided or omitted at 08·00 hours, with an ad libitum lunch provided at 12·30 and a 60 min bout of exercise performed at 17·00 hours. Despite the breakfast intervention occurring 9 h before exercise and consumption of an ad libitum lunch 4·5 h prior to exercise in both trials, a 4·5 % decrement of exercise performance was observed after breakfast omission⁽ Reference Clayton, Barutcu and Machin ^{28 )}. This data suggest that the effects of breakfast may be prolonged and therefore consumption of breakfast appears to be important for individuals aiming to maximise exercise performance.