Effect of Breakfast Omission on Energy Intake and Evening Exercise Performance

David J. Clayton; Asya Barutcu; Claire Machin; David J. Stensel; Lewis J. James

Disclosures

Med Sci Sports Exerc. 2015;47(12):2645-2652. 

In This Article

Discussion

The primary aim of this investigation was to determine the effect of BO/BC on subsequent energy intake and evening exercise performance. It was found that total work completed over a 30-min cycling performance test was reduced by approximately 4.5% after BO. Although energy intake was increased at lunch, this study also observed no difference in total ad libitum energy intake between trials, resulting in a reduced total 24-h energy intake after BO. From a weight management perspective, occasional BO could be used as a viable means of energy restriction in habitual breakfast consumers, although this may slightly impair exercise performance. Further study is required to determine whether BO can be used chronically to assist in long-term weight management.

The global increase in the prevalence of obesity has coincided with a gradual decline in BC,[15] with epidemiological evidence suggesting that those who regularly omit breakfast have a higher BMI than those who regularly consume breakfast.[3] However, because of several confounding factors, including variations in activity patterns[6] and dietary profiles,[14] there is a lack of causal data linking breakfast eating behavior with energy balance. The results of the current investigation demonstrate that the total energy restricted at breakfast is not accurately compensated for over an acute 24-h period, resulting in a net energy deficit of 2738 kJ. These findings are comparable with those of Levitsky and Pacanowski,[22] who found that total energy intake was reduced by approximately 1883 kJ after omitting an ad libitum breakfast meal. Similarly, 7-d consecutive BO was found to reduce energy intake by 670 kJ·d−1 on average compared with 7-d consecutive BC.[30] Taken collectively, data from these acute investigations suggest that, contrary to popular belief, BO does not lead to elevated energy intake over the course of the day and, as such, there is potential for BO to be used in successful weight management strategies.

Consistent with previous findings, energy intake at lunch was greater during BO than that during BC.[1,19,22,30] After the omission of breakfast, subjective appetite sensations were elevated throughout the morning compared with those when breakfast was consumed (Fig. 2), and accordingly, energy intake at lunch was increased by approximately 16%. However, this modest increase in energy intake (745 ± 604 kJ) only partially compensated for the energy deficit created by the omission of the breakfast meal (3095 ± 195 kJ), and as such, subjects remained in energy deficit throughout the afternoon. Similar to the findings in the current study, Levitsky and Pacanowski[22] reported elevations in hunger after the omission of an ad libitum breakfast meal, leading to increased energy consumption at lunch. Hubert et al.[19] found that reducing breakfast energy intake by 1824 kJ resulted in an average elevation in energy intake at a lunch of 500 kJ. The average compensation at lunch for BO is remarkably consistent between these studies, with the current investigation revealing 24% compensation at lunch compared with the 22%[22] and 26%[19] previously reported.

Concentrations of the orexigenic hormone acylated ghrelin and the anorexigenic hormone GLP-1(7–36) are thought to respond to fluxes in energy balance[8,17] and stimulate a behavioral response. In the current study, the increase in appetite observed throughout the morning period may have caused an increase in energy consumption during the time between breakfast and lunch in free-living conditions as found previously.[25] Acylated ghrelin and GLP-1(7–36) were only measured 4 h after BC/BO and immediately before exercise, so the dynamic response of these hormones to feeding may have been missed. After lunch, no differences were observed in subjective appetite sensations, which may suggest no difference in gut hormone concentrations. Accordingly, the appetitive responses to BO seem to be transient and do not influence energy intake after the provision of lunch.

Although there is general agreement in the literature that BO reduces daily energy intake, two investigations contest these findings. Astbury et al.[1] found that the provision of a 1080-kJ breakfast was completely compensated for in the no-breakfast condition at an ad libitum lunch meal. This study was designed primarily to investigate the effect of breakfast on gastrointestinal hormonal regulation of food intake and incorporated a liquid preload between breakfast and lunch that may have influenced energy intake at lunch. In addition, the provision of a low-energy breakfast (10% of daily energy requirements) has previously been shown to be more accurately compensated for at subsequent meals than higher-energy breakfast meals.[31] Farshchi et al.[11] aimed to investigate whether the timing of BC affected subsequent energy intake. Over a 2-wk period, subjects either consumed cereal and milk at a traditional breakfast time (0700–0800 a.m.) or later in the day (1200–1230 p.m.), which ensured that the energy provided was consistent across both interventions. Energy intake was found to be greater after BO compared with that after BC. This was likely due to the experimental design, which does not necessarily represent typical practice for those using BO as a method of weight management.

It is well documented that consuming breakfast improves exercise performance in the morning compared with omitting breakfast, i.e., exercising in a fasted state.[32,33] The current study found that exercise performance was also compromised in the evening after BO in the morning despite consuming lunch 4.5 h before exercise. Eating breakfast is highly encouraged in the literature to maximize CHO stores before competition,[38] as glucose availability may be a limiting factor because of glycogen depletion.[7] In particular, liver glycogen stores, which are important for blood glucose maintenance during exercise, have been shown to decrease by approximately 40% after an overnight fast.[36] Provision of a high-CHO breakfast will help replenish liver glycogen[16] and has been shown to increase muscle glycogen concentrations in the vastus lateralis by 11%–17%.[4,37] A recent study reported that 73% of female college athletes regularly omitted breakfast, resulting in suboptimal daily CHO and energy intakes.[34] This was also shown in the present study, as CHO intake before exercise was reduced during BO compared with that during BC (148 ± 65 vs 259 ± 73 g), which may have influenced glucose availability and reduced exercise performance. It seems that breakfast may play a central role in meeting the daily CHO requirements for exercising individuals and that BC might be important to maximize exercise performance throughout the day.

Fat oxidation was greater during the 30-min steady-state exercise period in BO. Increasing fat oxidation has been suggested to be beneficial for reducing fat mass and may also promote CHO sparing, potentially improving performance.[20] However, there was no difference in CHO oxidation between trials; therefore, it is unlikely that glycogen sparing occurred during BO. Accordingly, energy expenditure was greater during BO, which may be attributable to an increase in dietary-induced thermogenesis induced by greater energy intake at the previous ad libitum lunch meal. An increased contribution of dietary-induced thermogenesis to energy expenditure may also explain the higher HR observed during BO. After food intake, the splanchnic tissues require an increase in blood supply to assist in the digestion and absorption of nutrients. Therefore, during submaximal exercise, an increase in cardiac output is required to meet the oxygen requirements of both the skeletal muscles and splanchnic tissues.[39] Another indicator of sympathetic nervous activity is noradrenaline, which has been shown to peak after breakfast, with an attenuated response at subsequent feeding periods.[29] After the omission of breakfast, lunch becomes the first meal of the day. It could be considered that the sympathetic nervous response to feeding was greater after lunch during BO compared with that during BC; thus, HR was increased to a greater extent during steady-state exercise. Noradrenaline also increases lipolysis[21] and may explain the elevation in fat oxidation during the steady-state exercise on BO.

A limitation of any research that investigates BO is the difficulty in blinding subjects to the study intervention. In the multifactorial "central governor theory" model of fatigue described by Noakes,[28] the subjects' awareness of the study intervention may lead to an expectation with regard to exercise performance and performance may decline as a result. This may be particularly pertinent with the current study because all subjects were habitual breakfast consumers, so the withdrawal of breakfast in the morning may have produced a particularly strong expectation of reduced performance. This may partially account for the findings in this study.

It has recently been shown that the omission of breakfast over a 6-wk period has a negative effect on physical activity levels, reducing habitual physical activity thermogenesis on average by 1850 kJ·d−1 compared with that when breakfast was consumed.[2] Physical activity of this nature is difficult to manipulate or avoid because the nutritional intervention seemingly imposes a subconscious restriction on energy expenditure. Incorporating structured exercise into weight management programs may offset the magnitude of this deficit somewhat, provided that adherence to exercise is not affected. Although exercise performance might be important to maximize energy expenditure, the difference in exercise performance observed in the current study had a negligible influence on energy balance. Energy expenditure during the 30-min preload was approximately 80-kJ greater during BO, which was offset by an estimated reduction of energy expenditure of approximately 70 kJ during BO, assuming a cycling efficiency of 20%.[18] Therefore, net energy expenditure during exercise was almost identical between trials (2898 ± 307 (BC) vs 2905 ± 307 (BO) kJ; P = 0.834).

In conclusion, the results of the present study demonstrate that occasionally omitting breakfast may be an effective method of reducing energy intake over a 24-h period in habitual breakfast consumers. However, exercise performance may be compromised throughout the whole day after the omission of breakfast in the morning. Therefore, for those concerned with maximizing training and/or competition performance, BO might impair performance or interfere with training adaptation.

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