Effect of breakfast omission on subjective appetite, metabolism, acylated ghrelin and GLP-17-36 during rest and exercise

Breakfast omission induces compensatory eating behaviour at lunch, but often reduces daily energy intake. This study investigated the effect of breakfast omission on within-day subjective appetite, energy expenditure, substrate utilisation and appetite hormone profiles, in response to standardised feeding and exercise. Eight male, habitual breakfast eaters completed two randomised trials. Subjects arrived overnight fasted (0h), and either consumed (BC) or omitted (BO) a standardised breakfast (Mean (SD) (3085 (217) kJ). Lunch (4162 (510) kJ) and dinner (4914 (345) kJ) were provided at 4.5 and 10 h, respectively and subjects performed 60 min fixed-intensity cycling (50% VO 2 peak) at 8h. Blood samples were collected at 0, 4.5, 6 and 8 h, with expired air and subjective appetite sensations (hunger, fullness, desire to eat (DTE) and prospective food consumption (PFC)) collected throughout. Heart rate and perceived exertion were m easured during exercise. Hunger, DTE and PFC were greater and fullness lower during BO (P0.193). Resting energy expenditure was greater at 2.5 h during BC (P0.156). GLP-1 7-36 was greater (P<0.05) and acylated ghrelin tended to be greater (P=0.078) at 4.5 h during BC. Heart rate was greater on BO (P<0.05) during exercise. The results of this laboratory-controlled study suggest that the effects of breakfast omission are transient and do not extend beyond lunch, even when the negative energy balance created by breakfast omission is sustained via standardised feeding and exercise

The effect of breakfast on appetite regulation, energy balance and exercise performance

The belief that breakfast is the most important meal of day has been derived from cross-sectional studies that have associated breakfast consumption with a lower BMI. This suggests that breakfast omission either leads to an increase in energy intake or a reduction in energy expenditure over the remainder of the day, resulting in a state of positive energy balance. However, observational studies do not imply causality. A number of intervention studies have been conducted, enabling more precise determination of breakfast manipulation on indices of energy balance. This review will examine the results from these studies in adults, attempting to identify causal links between breakfast and energy balance, as well as determining whether consumption of breakfast influences exercise performance. Despite the associations in the literature, intervention studies have generally found a reduction in total daily energy intake when breakfast is omitted from the daily meal pattern. Moreover, whilst consumption of breakfast supresses appetite during the morning, this effect appears to be transient as the first meal consumed after breakfast seems to offset appetite to a similar extent, independent of breakfast. Whether breakfast affects energy expenditure is less clear. Whilst breakfast does not seem to affect basal metabolism, breakfast omission may reduce free-living physical activity and endurance exercise performance throughout the day. In conclusion, the available research suggests breakfast omission may influence energy expenditure more strongly than energy intake. Longer term intervention studies are required to confirm this relationship, and determine the impact of these variables on weight management

The effect of post-exercise drink macronutrient content on appetite and energy intake

Carbohydrate and protein ingestion post-exercise are known to facilitate muscle glycogen resynthesis and protein synthesis, respectively, but the effects of post-exercise nutrient intake on subsequent appetite are unknown. This study aimed to investigate whether protein induced satiety that has been reported at rest was still evident when pre-loads were consumed in a post-exercise context. Using a randomized, double blind, crossover design, 12 unrestrained healthy males completed 30 min of continuous cycling exercise at ~60% VO2peak, followed by five, 3 min intervals at ~85% VO2peak. Ten min post-exercise, subjects consumed 500 ml of either a low energy placebo (15 kJ) (PLA); a 6% whey protein isolate drink (528 kJ) (PRO); or a 6% sucrose drink (528 kJ) (CHO). Sixty min after drink ingestion, a homogenous ad-libitum pasta lunch was provided and energy intake at this lunch was quantified. Subjective appetite ratings were measured at various stages of the protocol. Energy consumed at the ad-libitum lunch was lower after PRO (5831 ± 960 kJ) than PLA (6406 ± 492 kJ) (P0.315). Considering the post-exercise drink, total energy intake was not different between trials (P=0.383). There were no differences between trials for any of the subjective appetite ratings. The results demonstrate that where post-exercise liquid protein ingestion may enhance the adaptive response of skeletal muscle, and this may be possible without affecting gross energy intake relative to consuming a low energy drink

Effect of breakfast omission on energy intake and evening exercise performance

Introduction: Breakfast omission may reduce daily energy intake. Exercising fasted impairs performance compared with exercising after breakfast, but the effect breakfast omission has on evening exercise performance is unknown. This study assessed the effect of omitting breakfast on evening exercise performance and within-day energy intake. Methods: Ten male, habitual breakfast eaters completed two trials in a randomized, counterbalanced order. Subjects arrived at the laboratory in an overnight-fasted state and either consumed or omitted a 733 ± 46 kcal (3095 ± 195 kJ) breakfast. Ad libitum energy intake was assessed at 4.5 h (lunch) and 11 h (dinner). At 9 h, subjects completed a 30-min cycling exercise at approximately 60% V˙O2peak, followed by a 30-min maximal cycling performance test. Food was not permitted for subjects once they left the laboratory after dinner until 0800 h the following morning. Acylated ghrelin, GLP-1(7–36), glucose, and insulin were assessed at 0, 4.5, and 9 h. Subjective appetite sensations were recorded throughout. Results: Energy intake was 199 ± 151 kcal greater at lunch (P < 0.01) after breakfast omission compared with that after breakfast consumption and tended to be greater at dinner after consuming breakfast (P = 0.052). Consequently, total ad libitum energy intake was similar between trials (P = 0.196), with 24-h energy intake 19% ± 5% greater after consuming breakfast (P < 0.001). Total work completed during the exercise performance test was 4.5% greater after breakfast (314 ± 53 vs 300 ± 56 kJ; P < 0.05). Insulin was greater during breakfast consumption at 4.5 h (P < 0.05), with no other interaction effect for hormone concentrations. Conclusions: Breakfast omission might be an effective means of reducing daily energy intake but may impair performance later that day, even after consuming lunch

Optimising intermittent fasting: evaluating the behavioural and metabolic effects of extended morning and evening fasting

This article describes the aims of a new study funded by the British Nutrition Foundation Drummond Pump Priming Award. This study will explore the independent metabolic, endocrinal and behavioural effects of extended morning and evening fasting. In an obesogenic society, there is an urgent need to identify effective strategies for preventing obesity‐related diseases, such as type 2 diabetes. Implementing extended periods of fasting and restricted time permitted for food intake may be an efficacious method for weight management and improving metabolic health. However, recent research suggests that the success of this intervention may be influenced by when the fasting window occurs, with evening fasting appearing to elicit superior metabolic benefits compared to morning fasting. The mechanisms driving these time‐dependent outcomes are not yet clear but may be due to circadian variations in metabolic physiology and in behaviours known to influence energy balance. To date, no study has directly compared the acute metabolic and behavioural responses to morning and evening fasting with those of a control trial. Research on evening fasting is also currently restricted to individuals living with overweight or obesity, emphasising a need for research in lean individuals aiming to maintain a healthy bodyweight and improve metabolic health. This article highlights the need for alternative nutritional interventions to improve public health, before reviewing the existing literature linking extended fasting, circadian rhythms and behavioural and metabolic outcomes. The final part of this article outlines the aims, methodology and intended outcomes of the current research project

Effect of 24-h severe energy restriction on appetite regulation and ad libitum energy intake in lean men and women

Background: Intermittent severe energy restriction (SER) can induce substantial weight loss, but the appetite regulatory responses to SER are unknown and may dictate long-term dietary adherence. Objective: We determined the effect of 24-h SER on appetite regulation, metabolism, and energy intake. Design: Eighteen lean men and women completed two 3-d trials in randomized, counterbalanced order. On day 1 subjects consumed standardized diets containing 100% (mean 6 SD: 9.3 6 1.3 MJ; energy balance) or 25% [2.3 6 0.3 MJ; energy restriction (ER)] of energy requirements. On day 2, a standardized breakfast was consumed, with plasma concentrations of acylated ghrelin, glucagon-like peptide 1, insulin, glucose, and nonesterified fatty acids determined for 4 h. Ad libitum energy intake was assessed at lunch and dinner with subjective appetite and resting metabolism assessed throughout. On day 3, ad libitum energy intake was assessed at breakfast and by weighed food records. Results: Energy intake was 7% greater on day 2 (P<0.05) during ER but not significantly different on day 3 (P=0.557). Subjective appetite was greater during ER on the morning of day 2 (P<0.05) but was not significantly different thereafter (P<0.145). During ER, postprandial concentrations of acylated ghrelin were lower (P<0.05), whereas glucose (P<0.05) and nonesterified fatty acids (P<0.0001) were higher. Postprandial glucagon-like peptide 17–36 (P=0.784) and insulin (P=0.06) concentrations were not significantly different between trials. Energy expenditure was lower during ER in the morning (P<0.01). Conclusions: In lean young adults, 24-h SER transiently elevated subjective appetite and marginally increased energy intake, but hormonal appetite markers did not respond in a manner indicative of hyperphagia. These results suggest that intermittent SER might be useful to attenuate energy intake and control body weight in this population. This trial was registered at www.clinicaltrials.gov.uk as NCT02696772

Acute effects of exercise on appetite, ad libitum energy intake and appetite-regulatory hormones in lean and overweight/obese men and women

Background: Acute exercise does not elicit compensatory changes in appetite parameters in lean individuals; however, less is known about responses in overweight individuals. This study compared the acute effects of moderate-intensity exercise on appetite, energy intake and appetite-regulatory hormones in lean and overweight/obese individuals. Methods: Forty-seven healthy lean (n=22, 11 females; mean (s.d.) 37.5 (15.2) years; 22.4 (1.5) kg m−2) and overweight/obese (n=25, 11 females; 45.0 (12.4) years, 29.2 (2.9) kg m−2) individuals completed two, 8 h trials (exercise and control). In the exercise trial, participants completed 60 min treadmill exercise (59 (4)% peak oxygen uptake) at 0–1 h and rested thereafter while participants rested throughout the control trial. Appetite ratings and concentrations of acylated ghrelin, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) were measured at predetermined intervals. Standardised meals were consumed at 1.5 and 4 h and an ad libitum buffet meal was provided at 7 h. Results: Exercise suppressed appetite (95% confidence interval (CI) −3.1 to −0.5 mm, P=0.01), and elevated delta PYY (95% CI 10 to 17 pg ml−1, P<0.001) and GLP-1 (95% CI 7 to 10 pmol l−1, P<0.001) concentrations. Delta acylated ghrelin concentrations (95% CI −5 to 3 pg ml−1, P=0.76) and ad libitum energy intake (95% CI −391 to 346 kJ, P=0.90) were similar between trials. Subjective and hormonal appetite parameters and ad libitum energy intake were similar between lean and overweight/obese individuals (Pgreater than or equal to0.27). The exercise-induced elevation in delta GLP-1 was greater in overweight/obese individuals (trial-by-group interaction P=0.01), whereas lean individuals exhibited a greater exercise-induced increase in delta PYY (trial-by-group interaction P<0.001). Conclusions: Acute moderate-intensity exercise transiently suppressed appetite and increased PYY and GLP-1 in the hours after exercise without stimulating compensatory changes in appetite in lean or overweight/obese individuals. These findings underscore the ability of exercise to induce a short-term energy deficit without any compensatory effects on appetite regardless of weight status

Severely restricting energy intake for 24 h does not affect markers of bone metabolism at rest or in response to re-feeding

Purpose: Intermittent energy restriction commonly refers to ad libitum energy intake punctuated with 24 h periods of severe energy restriction. This can improve markers of metabolic health but the effects on bone metabolism are unknown. This study assessed how 24 h severe energy restriction and subsequent refeeding affected markers of bone turnover. Methods: In a randomised order, 16 lean men and women completed 2, 48 h trials over 3 days. On day 1, participants consumed a 24 h diet providing 100% [EB: 9.27 (1.43) MJ] or 25% [ER: 2.33 (0.34) MJ] of estimated energy requirements. On day 2, participants consumed a standardised breakfast (08:00), followed by an ad libitum lunch (12:00) and dinner (19:30). Participants then fasted overnight, returning on day 3. Plasma concentrations of C-terminal telopeptide of type I collagen (CTX), procollagen type 1 N-terminal propeptide (P1NP) and parathyroid hormone (PTH) were assessed as indices of bone metabolism after an overnight fast on days 1–3, and for 4 h after breakfast on day 2. Results: There were no differences between trials in fasting concentrations of CTX, P1NP or PTH on days 1–3 (P [greater than] 0.512). During both trials, consuming breakfast reduced CTX between 1 and 4 h (P [less than] 0.001) and PTH between 1 and 2 h (P [less than] 0.05), but did not affect P1NP (P = 0.773) Postprandial responses for CTX (P = 0.157), P1NP (P = 0.148) and PTH (P = 0.575) were not different between trials. Ad libitum energy intake on day 2 was greater on ER [12.62 (2.46) MJ] than EB [11.91 (2.49) MJ]. Conclusions Twenty-four hour severe energy restriction does not affect markers of bone metabolism

Breakfast omission reduces subsequent resistance exercise performance

Although much research has examined the influence of morning carbohydrate intake (i.e., breakfast) on endurance performance, little is known about its effects on performance in resistance-type exercise. Sixteen resistance-trained men (age 23 ± 4 years, body mass 77.56 ± 7.13 kg, and height 1.75 ± 0.04 m) who regularly (≥3 day/wk) consumed breakfast completed this study. After assessment of 10 repetition maximum (10RM) and familiarization process, subjects completed 2 randomized trials. After an overnight fast, subjects consumed either a typical breakfast meal (containing 1.5 g of carbohydrate/kg; breakfast consumption [BC]) or a water-only breakfast (breakfast omission [BO]). Two hours later, subjects performed 4 sets to failure of back squat and bench press at 90% of their 10RM. Sensations of hunger, fullness, desire to eat, and prospective food consumption were collected before, as well as immediately, 1 hour and 2 hours after BC/BO using 100-mm visual analogue scales. Total repetitions completed were lower during BO for both back squat (BO: 58 ± 11 repetitions; BC: 68 ± 14 repetitions; effect size [ES] = 0.98; p < 0.001) and bench press (BO: 38 ± 5 repetitions; BC: 40 ± 5 repetitions; ES = 1.06; p < 0.001). Fullness was greater, whereas hunger, desire to eat, and prospective food consumption were lower after a meal for BC compared with BO (p < 0.001). The results of this study demonstrate that omission of a pre-exercise breakfast might impair resistance exercise performance in habitual breakfast consumers. Therefore, consumption of a high-carbohydrate meal before resistance exercise might be a prudent strategy to help maximize performanc

Anticipation of 24 h severe energy restriction increases energy intake and reduces physical activity energy expenditure in the prior 24 h, in healthy males

Intermittent fasting involves alternating between severely restricted and unrestricted energy intake. Physical activity energy expenditure (PAEE) is reduced during, and energy intake is elevated after, a period of energy restriction, but whether these are altered in anticipation of energy restriction is unknown. The aim of this study was to assess energy intake and PAEE in the 24 h before severe energy restriction. In randomised, counterbalanced order, 14 healthy males completed two 48 h trials over 3 days. On day 1, participants were informed which diet they would receive on day 2; either an energy balanced diet providing 100% (2755 (159) kcal; EB) or an energy restricted diet providing 25% (691 (42) kcal; ER), of their estimated energy requirements. Throughout day 1, ad-libitum energy intake was then determined from researcher-provided breakfast (08:30–09:00), lunch (12:30–13:00), afternoon snacks (14:00–18:00) and dinner (19:30–20:00). On day 2, participants consumed their allocated diet as instructed. On day 3, ad-libitum energy intake was assessed at breakfast (08:30–09:00). PAEE was measured throughout via integrated heart-rate and accelerometry monitors. Energy intake was 6% greater on day 1 (260 (344) kcal; P < 0.05) and 14% greater at breakfast on day 3 (223 (59) kcal; P < 0.05) during ER compared to EB. PAEE was 156 (252) kcal lower on day 1 (P < 0.05) and 239 (391) lower on day 2 (P < 0.05) during ER compared to EB. These behavioural compensations meant that the energy deficit produced by 24 h severe energy restriction was attenuated by 1108 (415) kcal (46%) over the study period (P < 0.0001). These results suggest that compensatory changes in energy intake and PAEE occur before, during and after an acute 24 h period of severe energy restriction, likely lessening the energy deficit created