Subjective Measures Of Appetite Research Articles

An extract of hops (Humulus lupulus L.) modulates gut peptide hormone secretion and reduces energy intake in healthy-weight men: a randomized, crossover clinical trial

Gastrointestinal enteroendocrine cells express chemosensory bitter taste receptors that may play an important role in regulating energy intake (EI) and gut function. To determine the effect of a bitter hop extract (Humulus lupulus L.) on acute EI, appetite, and hormonal responses. Nineteen healthy-weight men completed a randomized 3-treatment, double-blind, crossover study with a 1-wk washout between treatments. Treatments comprised either placebo or 500mg of hop extract administered in delayed-release capsules (duodenal) at 11:00h or quick-release capsules (gastric) at 11:30h. Ad libitum EI was recorded at the lunch (12:00h) and afternoon snack (14:00h), with blood samples taken and subjective ratings of appetite, gastrointestinal (GI) discomfort, vitality, meal palatability, and mood assessed throughout the day. Total ad libitum EI was reduced following both the gastric (4473kJ; 95% CI: 3811, 5134; P = 0.006) and duodenal (4439kJ; 95% CI: 3777, 5102; P = 0.004) hop treatments compared with the placebo (5383kJ; 95% CI: 4722, 6045). Gastric and duodenal treatments stimulated prelunch ghrelin secretion and postprandial cholecystokinin, glucagon-like peptide 1, and peptide YY responses compared with placebo. In contrast, postprandial insulin, glucose-dependent insulinotropic peptide, and pancreatic polypeptide responses were reduced in gastric and duodenal treatments without affecting glycemia. In addition, gastric and duodenal treatments produced small but significant increases in subjective measures of GI discomfort (e.g., nausea, bloating, abdominal discomfort) with mild to severe adverse GI symptoms reported in the gastric treatment only. However, no significant treatment effects were observed for any subjective measures of appetite or meal palatability. Both gastric and duodenal delivery of a hop extract modulates the release of hormones involved in appetite and glycemic regulation, providing a potential "bitter brake" on EI in healthy-weight men.

Perceptions of appetite do not match hormonal measures of appetite in trained competitive cyclists and triathletes following a ketogenic diet compared to a high-carbohydrate or habitual diet: A randomized crossover trial

Endurance athletes may implement rigid dietary strategies, such as the ketogenic diet (KD), to improve performance. The effect of the KD on appetite remains unclear in endurance athletes. This study analyzed the effects of a KD, a high-carbohydrate diet (HCD), and habitual diet (HD) on objective and subjective measures of appetite in trained cyclists and triathletes, and hypothesized that the KD would result in greater objective and subjective appetite suppression. Six participants consumed the KD and HCD for 2-weeks each, in a random order, following their HD. Fasting appetite measures were collected after 2-weeks on each diet. Postprandial appetite measures were collected following consumption of a ketogenic meal after the KD, high-carbohydrate meal after the HCD, and standard American/Western meal after the HD. Fasting total ghrelin (GHR) was lower and glucagon-like peptide-1 (GLP-1) and hunger were higher following the KD versus HD and HCD. Fasting insulin was not different. Mixed-effects model repeated measures analysis and effect sizes and 95% confidence intervals showed that postprandial GHR and insulin were lower and GLP-1 was higher following the ketogenic versus the standard and high-carbohydrate meals. Postprandial appetite ratings were not different across test meals. In conclusion, both fasting and postprandial concentrations of GHR were lower and GLP-1 were higher following the KD than the HC and HD, and postprandial insulin was lower on the KD. Subjective ratings of appetite did not correspond with the objective measures of appetite in trained competitive endurance athlete. More research is needed to confirm our findings.

Effect of processing on oat β-glucan viscosity, postprandial glycemic response and subjective measures of appetite.

Oat has procured its acclaim as a health promoting food partially due to its positive effect on glucose control. It has been demonstrated that oat β-glucan can interfere with postprandial glucose response. A large majority of this action is attributed to the increase in viscosity due to the β-glucan content in oat foods. While it is known that an increase in viscosity due to higher molecular weight of β-glucan can improve its glycemic effects, it is not known if an increase in viscosity attained by processing variables can further enhance the positive effect of oat on glucose control. In the current study we have examined the effect of kilning, tempering, microwaving, cooking, soaking and flaking on oat β-glucan viscosity. An acute randomized crossover clinical trial was also conducted to test oatmeal products containing low, medium and high β-glucan viscosity for their effect on postprandial glycemic response. Results from the processing experiments demonstrate that kilned samples, when tempered to 25% moisture and microwaved for 2 minutes, can produce much higher final viscosity compared to other samples with similar β-glucan content, molecular weight and solubility. However, results from the clinical trial show that the increase in the viscosity of the oat β-glucan attained through processing in this study did not have any effect on postprandial glucose control.

Effects of Whole Grain, Compared to Refined Grain, Intake on Subjective Measures of Appetite: A Systematic Review and Meta-Analysis

Abstract Objectives Results from observational studies indicate that whole grain intake is inversely associated with BMI and risk of weight gain. Whole grain intake may influence energy balance and body composition through effects on appetite and thus, energy intake. To evaluate the impact of whole grain food consumption on appetite, we performed a systematic review and meta-analysis of randomized controlled trials (RCTs) assessing whole grain food intake and subjective measures of appetite in adults. Methods A search of PubMed, Scopus and Food Science and Technology abstracts yielded 34 RCTs measuring hunger ratings after consuming whole grain foods compared to refined grain controls. Seventeen of these studies (598 subjects), with a total of 33 unique whole grain treatments, reported areas under the curve (AUC) for subjective hunger and were included in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMD). Results Intake of whole grain foods resulted in significantly lower subjective hunger AUC (range for AUC times ranged from 120 to 270 min) compared to refined grain foods [SMD −0.36, P < 0.001, 95% CI (−0.48, −0.24)]. Sensitivity analyses were also completed in which studies with AUC values for < and ≥ 180 min were evaluated separately, as well as hunger ratings at the 180 min timepoint alone, and the results were similar to those for the main analysis (SMDs −0.33 to −0.54, all P ≤ 0.03). Conclusions These results support the view that consumption of whole grain foods, compared to refined grain controls, significantly reduces subjective hunger, and this may provide at least part of the explanation for the inverse associations between whole grain food intake and risks for overweight, obesity and weight gain over time. Funding Sources This study was funded by the Bell Institute of Health and Nutrition, General Mills, Minneapolis, MN and registered with PROSPERO.

Circadian Rhythm of Substrate Oxidation and Hormonal Regulators of Energy Balance.

The circadian system provides an organism with the ability to anticipate daily food availability and appropriately coordinate metabolic responses. Few studies have simultaneouslyassessed factors involved in both the anticipation of energy availability (i.e., hormones involved in appetite regulation) and subsequent metabolic responses (such as energy expenditure and substrate oxidation) under conditions designed to reveal circadian rhythmicity. Eight healthy adults (four females; age: 28.0 ± 2.3 years; BMI: 24.3 ± 2.9 kg/m2 ) participated in a 26-hour constant routine protocol involving continuous wakefulness with constant posture, temperature, dim light, and hourly isocaloric snacks. Indirect calorimetry was performed every 3 hours for measurement of energy expenditure and substrate oxidation. Subjective hunger was obtained hourly using questionnaires. Saliva and plasma were obtained hourly to assess melatonin (circadian phase marker) and hormones (leptin, ghrelin, and peptide YY). Fat and carbohydrate oxidationwas highest in the biological evening and morning, respectively. Subjective hunger ratings peaked during the middle of the biological day. Significant circadian rhythms were identified for ghrelin and peptide YY with peaks in the biological evening and morning, respectively. These findings support a role for the circadian system in the modulation of nutrient oxidation, subjective measures of appetite, and appetitive hormones.

Resistant Starch Has No Effect on Appetite and Food Intake in Individuals with Prediabetes

BackgroundType 2 resistant starch (RS2) has been shown to improve metabolic health outcomes and may increase satiety and suppress appetite and food intake in humans. ObjectiveThis study assessed whether 12 weeks of daily RS2 supplementation could influence appetite perception, food intake, and appetite-related gut hormones in adults with prediabetes, relative to the control (CTL) group. DesignThe study was a randomized controlled trial and analysis of secondary study end points. Participants/settingSixty-eight adults (body mass index ≥27) aged 35 to 75 years with prediabetes were enrolled in the study at Pennington Biomedical Research Center (2012 to 2016). Fifty-nine subjects were included in the analysis. InterventionParticipants were randomized to consume 45 g/day of high-amylose maize (RS2) or an isocaloric amount of the rapidly digestible starch amylopectin (CTL) for 12 weeks. Main outcome measuresSubjective appetite measures were assessed via visual analogue scale and the Eating Inventory; appetite-related gut hormones (glucagon-like peptide 1, peptide YY, and ghrelin) were measured during a standard mixed-meal test; and energy and macronutrient intake were assessed by a laboratory food intake (buffet) test, the Remote Food Photography Method, and SmartIntake app. Statistical analyses performedData were analyzed using linear mixed models, adjusting for treatment group and time as fixed effects, with a significance level of α=.05. ResultsRS2 had no effect on subjective measures of appetite, as assessed by visual analogue scale (P>0.05) and the Eating Inventory (P≥0.24), relative to the CTL group. There were no effects of RS2 supplementation on appetite-related gut hormones, including glucagon-like peptide 1 (P=0.61), peptide YY (P=0.34), and both total (P=0.26) and active (P=0.47) ghrelin compared with the CTL. RS2 had no effect on total energy (P=0.30), carbohydrate (P=0.11), protein (P=0.64), or fat (P=0.37) consumption in response to a buffet meal test, relative to the CTL. In addition, total energy (P=0.40), carbohydrate (P=0.15), protein (P=0.46), and fat (P=0.53) intake, as quantified by the Remote Food Photography Method, were also unaffected by RS2, relative to the CTL. ConclusionsRS2 supplementation did not increase satiety or reduce appetite and food intake in adults with prediabetes.

A study protocol for a randomised crossover study evaluating the effect of diets differing in carbohydrate quality on ileal content and appetite regulation in healthy humans

Introduction: A major component of the digesta reaching the colon from the distal ileum is carbohydrate. This carbohydrate is subject to microbial fermentation and can radically change bacterial populations in the colon and the metabolites they produce, particularly short-chain fatty acids (SCFA). However, very little is currently known about the forms and levels of carbohydrate in the ileum and the composition of the ileal microbiota in humans. Most of our current understanding of carbohydrate that is not absorbed by the small intestine comes from ileostomy models, which may not reflect the physiology of an intact gastrointestinal tract. Methods: We will investigate how ileal content changes depending on diet using a randomised crossover study in healthy humans. Participants will be inpatients at the research facility for three separate 4-day visits. During each visit, participants will consume one of three diets, which differ in carbohydrate quality: 1) low-fibre refined diet; 2) high-fibre diet with intact cellular structures; 3) high-fibre diet where the cellular structures have been disrupted (e.g. milling, blending). On day 1, a nasoenteric tube will be placed into the distal ileum and its position confirmed under fluoroscopy. Ileal samples will be collected via the nasoenteric tube and metabolically profiled, which will determine the amount and type of carbohydrate present, and the composition of the ileal microbiota will be measured. Blood samples will be collected to assess circulating hormones and metabolites. Stool samples will be collected to assess faecal microbiota composition. Subjective appetite measures will be collected using visual analogue scales. Breath hydrogen will be measured in real-time as a marker of intestinal fermentation. Finally, an in vitro continuous fermentation model will be inoculated with ileal fluid in order to understand the shift in microbial composition and SCFA produced in the colon following the different diets. Registration: ISRCTN11327221.

Effects of Resistant Starch Ingestion on Postprandial Lipemia and Subjective Appetite in Overweight or Obese Subjects.

Reports surrounding the role of resistant starch (RS) on postprandial lipemia in humans are scarce. The aim of the present study is to examine the effects of resistant starch on the postprandial lipemic response, subjective measures of appetite, and energy intake in overweight and obese subjects. In a randomized, single-blind, crossover study, 14 overweight/obese participants ate a high-fat breakfast (679 kcal, 58% from fat) and a supplement with native banana starch (NBS), high-amylose maize starch (HMS), or digestible maize starch (DMS) on three separate occasions. All supplements provided were matched by the available carbohydrate content, and the RS quantity in NBS and HMS supplements was identical. Appetite was estimated using visual analogue scale (VAS) and an ad libitum test meal. Postprandial glycemia, triglycerides, cholesterol, high-density lipoprotein (HDL) cholesterol, and insulin excursions did not differ between treatments. Subjective appetite measures of satiety were significantly increased after HMS; however, no effects on energy intake were observed during the ad libitum test meal. These findings suggest that a single acute dose of RS cannot be expected to improve postprandial lipemia in subjects with overweight or obesity on a high-fat meal. However, the potential benefits of long-term supplementation should not be ruled out based on these results.

MON-111 Amenorrhea In Exercising Women Is Associated With A Greater Reduction In Post-prandial Ghrelin

Ghrelin and peptide YY (PYY) are appetite related hormones which may influence energy balance. In anorexia nervosa, a model of severe energy deficiency, ghrelin and PYY remain elevated after consuming a standardized meal and may be related to the etiology of the disorder. Amenorrhea in exercising women is associated with significant but less severe energy deficiency. Whether alterations in gut hormone responses to a single meal contribute to energy deficiency in this population is unclear. The purpose of this investigation was to compare the postprandial response of PYY and ghrelin to a mixed meal in amenorrheic (AMEN n=7) and eumenorrheic (EUMEN n=9) exercising women. Menstrual status was assessed by self report history of menses and confirmed by daily urinary measures of estrogen and progesterone metabolites. Serial blood draws and subjective appetite measures were obtained before consuming a 700kcal standardized mixed composition meal (14% PRO, 64% CHO, 22% FAT) and at regular intervals until 180 minutes post. PYY (3-36) and total ghrelin were assayed in serum by RIA. Baseline Total T3 was assessed by Immulite. Statistical analyses included independent t-tests, two-way repeated measures ANOVA (LSD post-hoc), and correlations. Subjects were similar in age (23±1 yrs), height (168±2 cm), and weight (61.0±1.6 kg). AMEN had lower Total T3 at baseline compared to EUMEN (55.3±3.7, 76.1±4.8, p=0.01). PYY increased from pre (29.8±3.9 pmol/L) to 15min post (34.1±4.1 pmol/L) (time; p<0.001) and remained elevated through 180 minutes. Change in ghrelin depended on group (time*group; p=0.02), such that ghrelin was significantly greater in AMEN than EUMEN (2810.1±456.4 pg/mL, 1511.2±138.9 pg/mL; p=0.03) prior to the meal and both absolute (1709.7±352.2 pg/mL, 593.8±125.3 pg/mL, p=0.02) and percent decrease (55.8 ±5.9%, 36.6±4.7%, p=0.02) in ghrelin from PRE to nadir were significantly greater in AMEN than EUMEN. AUC for change from baseline through 180 min was significantly greater in AMEN than EUMEN (14941.8±2455.4, 4675.2±1089.1, p=0.001) for ghrelin but did not differ for PYY (130.7±29.7, 108.4±36.3, p=0.67). There were no differences in subjective appetite scores of hunger and satiety between groups and change in appetite score was not correlated with baseline ghrelin or PYY. Baseline ghrelin was highly correlated with nadir (r=0.81, p<0.001) and AUC (r=.86, p<0.001). These results suggest ghrelin, an orexigenic hormone, is elevated in conditions of energy deficiency which may be an adaptive response to increase energy intake and reverse the underlying energy deficit. The greater magnitude of ghrelin suppression following meal consumption in amenorrheic women may be related to the elevated baseline concentration. Future studies should explore if the greater meal related decline in ghrelin is related to reduced food intake or increased satiety. Childhood Obesity Prevention Training grant.

A study protocol for a randomised crossover study evaluating the effect of diets differing in carbohydrate quality on ileal content and appetite regulation in healthy humans

Introduction:A major component of the digesta reaching the colon from the distal ileum is carbohydrate. This carbohydrate is subject to microbial fermentation and can radically change bacterial populations in the colon and the metabolites they produce, particularly short-chain fatty acids (SCFA). However, very little is currently known about the forms and levels of carbohydrate in the ileum and the composition of the ileal microbiota in humans. Most of our current understanding of carbohydrate that is not absorbed by the small intestine comes from ileostomy models, which may not reflect the physiology of an intact gastrointestinal tract.Methods:We will investigate how ileal content changes depending on diet using a randomised crossover study in healthy humans. Participants will be inpatients at the research facility for three separate 4-day visits. During each visit, participants will consume one of three diets, which differ in carbohydrate quality: 1) low-fibre refined diet; 2) high-fibre diet with intact cellular structures; 3) high-fibre diet where the cellular structures have been disrupted (e.g. milling, blending). On day 1, a nasoenteric tube will be placed into the distal ileum and its position confirmed under fluoroscopy. Ileal samples will be collected via the nasoenteric tube and metabolically profiled, which will determine the amount and type of carbohydrate present, and the composition of the ileal microbiota will be measured. Blood samples will be collected to assess circulating hormones and metabolites. Stool samples will be collected to assess faecal microbiota composition. Subjective appetite measures will be collected using visual analogue scales. Breath hydrogen will be measured in real-time as a marker of intestinal fermentation. Finally, anin vitrocontinuous fermentation model will be inoculated with ileal fluid in order to understand the shift in microbial composition and SCFA produced in the colon following the different diets.Registration:ISRCTN11327221.

Pre-sleep protein in casein supplement or whole-food form has no impact on resting energy expenditure or hunger in women.

The purpose of this study was to determine the effect of a whole-food protein (cottage cheese, CC) consumed before sleep on next-morning resting energy expenditure (REE), RER and appetite compared with an isoenergetic/isonitrogenous casein protein (CP) supplement and placebo (PL) in active women. In a beverage-blinded, randomised, cross-over design, ten active women (age, 23·1 (sd 1·9) years; body fat, 22·0 (sd 4·6) %) consumed pre-sleep CC (30 g of protein, 10 g of carbohydrate and 0 g of fat) or energy- and protein-matched liquid CP or PL (0 kJ). Participants arrived at 18.00 hours for an overnight stay in the laboratory. At 30-60 min before normal bed time (2 h post standard meal), participants consumed CC, CP or PL before measurement of REE. Upon waking (05.00-08.00 hours), REE was repeated and subjective appetite was recorded. Statistical analyses were conducted using repeated-measures ANOVA (SPSS). Significance was accepted at P≤0·05. There were no significant differences in acute REE (CC, 7217 (sd 1368); CP, 7188 (SD 895); PL, 7075 (sd 1108) kJ/d, P=0·95), acute RER (0·79 (sd 0·05), P=0·56), morning REE (CC, 5840 (sd 1225); CP, 5694 (sd 732); PL, 5991 (sd 903) kJ/d, P=0·79) or morning RER (0·77 (sd 0·03), P=0·52). Subjective measures of appetite were not different between groups. In active women, pre-sleep consumption of CC does not alter REE or RER more than a CP or PL beverage. These data suggest that the metabolic response from whole-food protein do not differ from the metabolic response of liquid protein.

The effect of L-rhamnose on intestinal transit time, short chain fatty acids and appetite regulation: a pilot human study using combined 13CO2/H2 breath tests

Background. The appetite-regulating effects of non-digestible carbohydrates (NDC) have in part previously been attributed to their effects on intestinal transit rates as well as microbial production of short chain fatty acids (SCFA). Increased colonic production of the SCFA propionate has been shown to reduce energy intake and stimulate gut hormone secretion acutely in humans. Objective. We investigated the effect of the propiogenic NDC, L-rhamnose, on gastrointestinal transit times using a combined 13CO2/H2 breath test. We hypothesised that L-rhamnose would increase plasma propionate leading to a reduction in appetite, independent of changes in gastrointestinal transit times. Design. We used a dual 13C-octanoic acid/lactose 13C-ureide breath test combined with breath H2 to measure intestinal transit times following the consumption of 25 g d−1 L-rhamnose, compared with inulin and cellulose, in 10 healthy humans in a randomised cross-over design pilot study. Gastric emptying (GE) and oro-caecal transit times (OCTTs) were derived from the breath 13C data and compared with breath H2. Plasma SCFA and peptide YY (PYY) were also measured alongside subjective measures of appetite. Results. L-rhamnose significantly slowed GE rates (by 19.5 min) but there was no difference in OCTT between treatments. However, breath H2 indicated fermentation of L-rhamnose before it reached the caecum. OCTT was highly correlated with breath H2 for inulin but not for L-rhamnose or cellulose. L-rhamnose consumption significantly increased plasma propionate and PYY but did not significantly reduce subjective appetite measures. Conclusions. The NDCs tested had a minimal effect on intestinal transit time. Our data suggest that L-rhamnose is partially fermented in the small intestine and that breath H2 reflects the site of gastrointestinal fermentation and is only a reliable marker of OCTT for certain NDCs (e.g. inulin). Future studies should focus on investigating the appetite-suppressing potential of L-rhamnose and verifying the findings in a larger cohort.

Very Low Volume Sprint Interval Exercise Suppresses Subjective Appetite, Lowers Acylated Ghrelin, and Elevates GLP-1 in Overweight Individuals: A Pilot Study.

High-intensity exercise has been shown to elicit a transient suppression of appetite and create a more anorexigenic profile of appetite-associated hormones. It is yet to be fully elucidated whether such a response is observed following very low-volume, intermittent exercise at supramaximal intensity in those who are overweight. Eight overweight individuals (BMI 27.7 ± 1.7 kg·m2) completed resting (REST) and exercise (EX) trials in a counterbalanced order. EX consisted of 4 × 30 s “flat-out” cycling on an ergometer (adapted Wingate test). Two hours post-exercise (or REST), participants were presented with an ad libitum meal. Subjective appetite measures and blood samples were obtained throughout. Subjective appetite, measured using VAS, was significantly lower immediately after exercise compared with REST (38.0 ± 28.5 mm vs. 75.1 ± 26.2 mm, p = 0.018, d = 1.09). This difference remained significant 30 min post-exercise. Acylated ghrelin concentration was suppressed in EX compared with REST immediately post-exercise (113.4 ± 43.0 pg·mL−1 vs. 189.2 ± 91.8 pg·mL−1, p = 0.03, d = 1.07) and remained lower until the ad libitum test-meal. Area-under-the-curve for GLP-1 concentration was significantly greater for EX, versus REST. There was no difference in absolute ad libitum intake or relative energy intake. As little as 4 × 30 s of “flat-out” cycling was sufficient to elicit a transient suppression of appetite and an enduring suppression of plasma acylated ghrelin. Nonetheless, food intake 2-h post-exercise was unaffected.

Appetite responses to high-fat meals or diets of varying fatty acid composition: a comprehensive review.

Dietary fatty acids (FA) act as signaling molecules with diverse effects on physiologic function. The aim of this article is to review and summarize the clinical human studies in the literature on how dietary FA composition in meals and diets affects hunger and satiety signaling in the body. Studies examining FA saturation (monounsaturated (MUFA), saturated or polyunsaturated (PUFA) FAs) or FA chain length from high-fat meals/diets were included. Measures of appetite included visual analog scale (VAS) questionnaires, appetite hormones (Cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), peptide YY (PYY), gastric insulinotropic polypeptide gastric inhibitory peptide (GIP), ghrelin, leptin, insulin) and/or energy intake (EI) data. VAS measures in 9 out of 13 studies were not influenced by FA saturation. PUFAs, followed by MUFAs, tended to induce the greatest stimulatory effect on GLP-1, GIP and PYY, which was found in 6 out of 11 studies measuring appetite-related hormones. Regarding FA chain length, five of six studies show either no difference or less hunger (VAS) and greater satiety hormone levels (two of six studies) for FAs with longer chain lengths. EI does not seem to be affected by the saturation of FAs while EI was inconclusive for studies comparing FA chain length. Possibly due to the inconsistencies in study design, little agreement is observed between the studies on the impact of FA composition on hormonal and subjective measures of appetite as well as EI. Therefore, more research on the long-term impact of dietary FA composition on appetite control may provide clearer outcomes.

Methodological Challenges in Studies Examining the Effects of Breakfast on Cognitive Performance and Appetite in Children and Adolescents.

Breakfast is purported to confer a number of benefits on diet quality, health, appetite regulation, and cognitive performance. However, new evidence has challenged the long-held belief that breakfast is the most important meal of the day. This review aims to provide a comprehensive discussion of the key methodological challenges and considerations in studies assessing the effect of breakfast on cognitive performance and appetite control, along with recommendations for future research. This review focuses on the myriad challenges involved in studying children and adolescents specifically. Key methodological challenges and considerations include study design and location, sampling and sample section, choice of objective cognitive tests, choice of objective and subjective appetite measures, merits of providing a fixed breakfast compared with ad libitum, assessment and definition of habitual breakfast consumption, transparency of treatment condition, difficulty of isolating the direct effects of breakfast consumption, untangling acute and chronic effects, and influence of confounding variables. These methodological challenges have hampered a clear substantiation of the potential positive effects of breakfast on cognition and appetite control and contributed to the debate questioning the notion that breakfast is the most important meal of the day.

Whey protein consumption after resistance exercise reduces energy intake at a post-exercise meal

PurposeProtein consumption after resistance exercise potentiates muscle protein synthesis, but its effects on subsequent appetite in this context are unknown. This study examined appetite and energy intake following consumption of protein- and carbohydrate-containing drinks after resistance exercise.MethodsAfter familiarisation, 15 resistance training males (age 21 ± 1 years, body mass 78.0 ± 11.9 kg, stature 1.78 ± 0.07 m) completed two randomised, double-blind trials, consisting of lower-body resistance exercise, followed by consumption of a whey protein (PRO 23.9 ± 3.6 g protein) or dextrose (CHO 26.5 ± 3.8 g carbohydrate) drink in the 5 min post-exercise. An ad libitum meal was served 60 min later, with subjective appetite measured throughout. Drinks were flavoured and matched for energy content and volume. The PRO drink provided 0.3 g/kg body mass protein.ResultsAd libitum energy intake (PRO 3742 ± 994 kJ; CHO 4172 ± 1132 kJ; P = 0.007) and mean eating rate (PRO 339 ± 102 kJ/min; CHO 405 ± 154 kJ/min; P = 0.009) were lower during PRO. The change in eating rate was associated with the change in energy intake (R = 0.661, P = 0.007). No interaction effects were observed for subjective measures of appetite. The PRO drink was perceived as creamier and thicker, and less pleasant, sweet and refreshing (P < 0.05).ConclusionThese results suggest whey protein consumption after resistance exercise reduces subsequent energy intake, and this might be partially mediated by a reduced eating rate. Whilst this reduced energy intake is unlikely to impair hypertrophy, it may be of value in supporting an energy deficit for weight loss.

The effects of intermittent compared to continuous energy restriction on glycaemic control in type 2 diabetes; a pragmatic pilot trial

AimsWeight loss improves glycaemic control in type 2 diabetes mellitus (T2DM). However, as achieving and maintaining weight loss is difficult, alternative strategies are needed. Our primary aim was to investigate the effects of intermittent energy restriction (IER) compared to continuous energy restriction (CER) on glycated haemoglobin A1c (HbA1c). Secondary aims were to assess effects on weight loss, body composition, medication changes and subjective measures of appetite. Using a 2-day IER method, we expected equal improvements to HbA1c and weight in both groups. MethodSixty-three overweight or obese participants (BMI 35.2±5kg/m2) with T2DM (HbA1c 7.4±1.3%) (57mmol/mol) were randomised to a 2-day severe energy restriction (1670-2500kJ/day) with 5days of habitual eating, compared to a moderate CER diet (5000-6500kJ/day) for 12weeks. ResultsAt 12weeks HbA1c (−0.7±0.9% P<0.001) and percent body weight reduction (−5.9±4% P<0.001) was similar in both groups with no group by time interaction. Similar reductions were also seen for medication dosages, all measures of body composition and subjective reports of appetite. ConclusionsIn this pilot trial, 2days of IER compared with CER resulted in similar improvements in glycaemic control and weight reduction offering a suitable alternative treatment strategy.

Physiological and molecular responses to an acute bout of reduced-exertion high-intensity interval training (REHIT).

We have previously shown that 6 weeks of reduced-exertion high-intensity interval training (REHIT) improves VO2max in sedentary men and women and insulin sensitivity in men. Here, we present two studies examining the acute physiological and molecular responses to REHIT. In Study 1, five men and six women (age: 26 ± 7 year, BMI: 23 ± 3 kg m(-2), VO2max: 51 ± 11 ml kg(-1) min(-1)) performed a single 10-min REHIT cycling session (60 W and two 20-s 'all-out' sprints), with vastus lateralis biopsies taken before and 0, 30, and 180 min post-exercise for analysis of glycogen content, phosphorylation of AMPK, p38 MAPK and ACC, and gene expression of PGC1α and GLUT4. In Study 2, eight men (21 ± 2 year; 25 ± 4 kg·m(-2); 39 ± 10 ml kg(-1) min(-1)) performed three trials (REHIT, 30-min cycling at 50 % of VO2max, and a resting control condition) in a randomised cross-over design. Expired air, venous blood samples, and subjective measures of appetite and fatigue were collected before and 0, 15, 30, and 90 min post-exercise. Acutely, REHIT was associated with a decrease in muscle glycogen, increased ACC phosphorylation, and activation of PGC1α. When compared to aerobic exercise, changes in VO2, RER, plasma volume, and plasma lactate and ghrelin were significantly more pronounced with REHIT, whereas plasma glucose, NEFAs, PYY, and measures of appetite were unaffected. Collectively, these data demonstrate that REHIT is associated with a pronounced disturbance of physiological homeostasis and associated activation of signalling pathways, which together may help explain previously observed adaptations once considered exclusive to aerobic exercise.

Carbohydrate-rich breakfast attenuates glycaemic, insulinaemic and ghrelin response to ad libitum lunch relative to morning fasting in lean adults.

Breakfast omission is associated with obesity and CVD/diabetes, but the acute effects of extended morning fasting upon subsequent energy intake and metabolic/hormonal responses have received less attention. In a randomised cross-over design, thirty-five lean men (n 14) and women (n 21) extended their overnight fast or ingested a typical carbohydrate-rich breakfast in quantities relative to RMR (i.e. 1963 (sd 238) kJ), before an ad libitum lunch 3 h later. Blood samples were obtained hourly throughout the day until 3 h post-lunch, with subjective appetite measures assessed. Lunch intake was greater following extended fasting (640 (sd 1042) kJ, P< 0.01) but incompletely compensated for the omitted breakfast, with total intake lower than the breakfast trial (3887 (sd 1326) v. 5213 (sd 1590) kJ, P< 0.001). Systemic concentrations of peptide tyrosine-tyrosine and leptin were greater during the afternoon following breakfast (both P< 0.05) but neither acylated/total ghrelin concentrations were suppressed by the ad libitum lunch in the breakfast trial, remaining greater than the morning fasting trial throughout the afternoon (all P< 0.05). Insulin concentrations were greater during the afternoon in the morning fasting trial (all P< 0.01). There were no differences between trials in subjective appetite during the afternoon. In conclusion, morning fasting caused incomplete energy compensation at an ad libitum lunch. Breakfast increased some anorectic hormones during the afternoon but paradoxically abolished ghrelin suppression by the second meal. Extending morning fasting until lunch altered subsequent metabolic and hormonal responses but without greater appetite during the afternoon. The present study clarifies the impact of acute breakfast omission and adds novel insights into second-meal metabolism.

Influence of the tolerability of vinegar as an oral source of short-chain fatty acids on appetite control and food intake

Vinegar is promoted as a natural appetite suppressant, based on previous reports that vinegar ingestion significantly increases subsequent satiety. However there are concerns about the appropriateness and safety of this advice, and it is unclear if poor product palatability may explain previously published effects on appetite. To investigate if vinegar palatability and tolerability have a role in suppressing appetite and food intake in two sequential and related acute human feeding studies. Healthy, young, normal weight unrestrained eaters were recruited to Study 1 (n=16), an acute feeding study supplying vinegar within both palatable and unpalatable drinks alongside a mixed breakfast in comparison to a non-vinegar control; and to Study 2 (n=14), a modified sham feeding study (taste only without ingestion) comparing vinegar to a non-vinegar control following a milkshake preload. Both studies were a randomized crossover balanced design for the assessment of appetite, energy intake and glycaemic response. In Study 1, ingestion of vinegar significantly reduced quantitative and subjective measures of appetite, which were accompanied by significantly higher nausea ratings, with unpalatable treatment having the greatest effect. Significant correlations between palatability ratings and appetite measures were found. In Study 2, orosensory stimulation with vinegar did not influence subsequent subjective or quantitative measures of appetite compared with control. These studies indicate that vinegar ingestion enhances satiety whereas orosensory stimulation alone does not, and that these effects are largely due to poor tolerability following ingestion invoking feelings of nausea. On this basis the promotion of vinegar as a natural appetite suppressant does not seem appropriate.