Shift Work is Associated with an Elevated White Blood Cell Count: A Systematic Review and Meta-Analysis

The white blood cell (WBC) count increases significantly in reaction to infections and certain chronic diseases. Shift employment increases the risk for chronic low-grade inflammation and the progression of several chronic diseases. The objective of this study was to systematically evaluate the evidence from studies on total and differential WBC counts in shift employees. A literature search was performed in PubMed®, Web of Science, and Scopus databases using keywords for research published before March 1, 2022. A meta-analysis was conducted for total and differential WBC counts using a random-effects approach. A total of 25 studies covering a sample of 37,708 day and shift employees were included in this review. The studies represented America, Europe, East Asia, and Middle East. A significant increase in the total counts (×109/L) of WBC [mean difference (MD) = 0.43; 95% confidence interval (CI): 0.34-0.52; P < 0.001], lymphocytes (MD = 0.16; 95% CI: 0.02-0.30; P = 0.02), monocytes (MD = 0.04; 95% CI: 0-0.07; P = 0.03), and eosinophils (MD = 0.01; 95% CI: 0-0.01; P = 0.03) was observed in shift workers compared to the day counterparts. However, neutrophils and basophils were not significantly different between the groups. Shift work significantly increases the total and differential blood counts in peripheral circulation. Therefore, total and differential WBC counts represent a relatively inexpensive biomarker for diagnostics and prognostics of diseases in shift workers.

A qualitative exploration of the experiences of shift workers participated in a low-calorie meal replacement dietary intervention

OBJECTIVES

Shift work is associated with various health challenges, including obesity and metabolic disturbances. To address these concerns, a randomised controlled clinical trial was conducted to evaluate the efficacy of a low-calorie meal replacement (MR) dietary intervention for dinner among shift workers with obesity. This study focuses on the qualitative aspects of this intervention, aiming to explore the experiences and perceptions of shift workers who participated in the trial.

DESIGN

Following the completion of the intervention, semi-structured face-to-face or telephone interviews were conducted with a purposive sample of trial participants. Data analysis was inductive, thematic using NVivo V.10 software.

SETTING

The intervention was conducted among shift workers with obesity in a private hospital in Sri Lanka and resulted in a modest decrease in weight.

PARTICIPANTS

Using purposeful maximum variation sampling, we recruited eight healthcare shift workers who took part in a weight loss intervention.

RESULTS

All participants expressed satisfaction with the MR meal for dinner, highlighting its positive impact on their well-being. Despite initial difficulties, strong determination and motivation by results supported adherence. Some participants suggested that the MR could be improved with sweeter taste and more flavour options. Few reported mild bloating at the beginning, but no serious side effects were noted. Participants felt lighter in their bodies due to weight loss. The method's simplicity was the most frequently reported benefit, making it feasible even during busy night shifts. Overall, participants highly recommended the intervention to others in need.

CONCLUSION

Participants experienced weight loss by replacing their dinner with the MR. This study offers valuable insights for tailoring future workplace-based dietary interventions for this vulnerable population.

TRIAL REGISTRATION NUMBER

ACTRN12622000231741.

The effect of shift work on different hematological parameters among healthcare workers

Shift workers frequently experience alterations in their circadian rhythms, which are correlated with variations in hematological parameters. Changes in blood cells may be related to an individual's health status. Therefore, this study aimed to compare the relationship between shift work and changes in blood cells among a group of healthcare workers in Sri Lanka. A comparative cross-sectional study was conducted among healthcare workers, recruited by a stratified random sampling technique. Socio-demographic data were collected using a structured questionnaire. Venous blood samples were obtained and analyzed for the determination of total and differential blood cell counts. Descriptive statistics were used for the analysis of sociodemographic and hematological parameters. A sample of 37-day workers and 39 shift workers were included in the analysis. The mean ages (years) were not significantly different between the groups (36.8 ± 10.8 vs 39.1 ± 12.0; P = 0.371). Shift employees showed a significantly higher total mean white blood cell count (WBC) of 7548.75 mm-3 compared to day workers' 6869.19 mm-3 (P = 0.027). They also had higher mean absolute counts for all different WBC types (Neutrophils: 3949.2 vs 3557.7  , Lymphocyte: 2756.5 vs 2614.2  , Eosinophil: 317.6 vs 233.4  , Monocytes: 491.63 vs 432.51  , Basophils: 31.68 vs 29.22  ). Shift employees exhibited higher WBC counts than day workers at the same level of work experience. The length of shift work exposure revealed a positive link with neutrophil (r = 0.225  ) and eosinophil counts (r = 0.262  ), whereas these correlations were negative for day workers. Shift workers were associated with higher WBC counts in healthcare workers compared to their day-working counterparts.

The efficacy of morning versus evening exercise for weight loss: A randomized controlled trial

OBJECTIVE

The aim of this study was to investigate the influence of morning versus evening exercise on weight loss, cardiometabolic health, and components of energy balance.

METHODS

A total of 100 inactive adults with overweight or obesity were randomized to morning exercise (AMEx; 06:00-09:00), evening exercise (PMEx; 16:00-19:00), or wait-list control (CON). AMEx and PMEx were prescribed 250 min·wk^-1 of self-paced aerobic exercise for 12 weeks. Anthropometry and body composition, physical activity, and dietary intake were assessed at baseline, 6 weeks, and 12 weeks. Cardiorespiratory fitness (V̇O₂ peak), resting metabolic rate, and blood markers were assessed at baseline and 12 weeks. Body composition and V̇O₂ peak were also measured at 3- and 6-month follow-up.

RESULTS

AMEx and PMEx lost weight during the intervention (mean [SD], AMEx, -2.7 [2.5] kg, p < 0.001; PMEx, -3.1 [3.4] kg, p < 0.001). V̇O₂ peak significantly increased in both intervention groups, and these changes were different from CON (AMEx, +4.7 mL·kg^-1 ·min^-1 , p = 0.034; PMEx, +4.2 mL·kg^-1 ·min^-1 , p = 0.045). There were no between-group differences for resting metabolic rate or physical activity. At 12 weeks, total energy intake was significantly reduced in both AMEx and PMEx versus CON (AMEx, -3974 kJ, p < 0.001; PMEx, -3165 kJ, p = 0.001).

CONCLUSIONS

Adults with overweight and obesity experience modest weight loss in response to an exercise program, but there does not appear to be an optimal time to exercise.

Meal replacement as a weight loss strategy for night shift workers with obesity: a protocol for a randomized controlled trial

BACKGROUND

Shift work is considered a risk factor for a number of chronic health conditions including obesity. Weight reduction in obese patients lowers the risk for cardiovascular disease, diabetes, certain cancers, and mortality. Achieving a negative energy balance by providing low-calorie meal replacements is widely used for weight management. This study aims to evaluate the impact of a low-calorie "meal-replacement" on the weight and metabolic parameters of shift workers with obesity.

METHODS

This trial will be conducted in a parallel, randomized controlled design for a period of 8 weeks. A total of 44 shift workers with body mass index over 25 kg/m² will be recruited after assessing eligibility. Participants will be randomly assigned to the test and control groups on a 1:1 ratio. The intervention group (N = 22) will be provided with a low-calorie (~200 kcal) meal replacement shake as dinner, and the control group (N = 22) will continue their habitual diets. The visits and the evaluations will be done as follows: screening (visit 0), 4 weeks (visit 1), and 8 weeks (visit 2). Anthropometric measurements will be taken at 0, 4, and 8 weeks. Body composition, biochemical parameters, dietary intake, and physical activity will be assessed during the first and the last visit.

OUTCOMES

The primary outcome will be the proportion of participants that had a 5% body weight loss from baseline. The secondary outcomes will be post-intervention changes in other metabolic parameters.

DISCUSSION

To our knowledge, this is one of the first randomized controlled trials evaluating the effects of a meal replacement as the night meal for weight loss in shift workers with obesity. Moreover, improvement of metabolic parameters in shift workers will be an added benefit to this high-risk group.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622000231741 . Registered on 09 February 2022.

Shift work and the risk for metabolic syndrome among healthcare workers: A systematic review and meta-analysis

Shift work, defined as work occurring outside typical daytime working hours, is associated with an increased risk for metabolic syndrome (MetS) due to several biological and environmental changes. The MetS refers to the clustering of several known cardiovascular risk factors, including insulin resistance, obesity, dyslipidemia, and hypertension. This systematic review aims to evaluate the literature on the association between shift work and the risk of MetS in employees of the health sector. A systematic search was conducted in PubMed, Web of Science, and Scopus databases using appropriate keywords for studies published before September 1, 2021. Eligible studies were those that compared the prevalence of MetS between day and shift healthcare workers; had a cross-sectional, case-control, or cohort study design; provided sufficient data for calculating odds ratios or relative risks with 95% confidence intervals; and articles in English. The Joanna Briggs Institute prevalence critical appraisal tool was used for quality analysis. Risk for MetS and related measures of effect size were retrieved from studies for meta-analysis. Twelve studies met the criteria for inclusion in the review and meta-analysis. Sample sizes ranged from 42 to 738, and the age range of subjects was between 18 and 65 years. Ten studies demonstrated high methodological quality, while two studies were of average quality. Ten out of 12 studies in the review demonstrated a higher risk in shift workers for developing MetS than day workers. The pooled OR of MetS in shift workers based on 12 studies was 2.17 (95% CI = 1.31-3.60, P = 0.003; I²  = 82%, P < 0.001). Shift workers exhibited more than a twofold increase in the chance of developing MetS in comparison with day workers.

COVID-19 patients with obesity at risk for worse outcomes despite younger age and fewer inflammatory derangements

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a viral pulmonary infection that can progress to cytokine storm syndrome because of widespread dysregulated inflammatory response. Many patients at risk for severe COVID-19 manifestation have been identified as those with preexisting conditions of pulmonary origin, as well as conditions that impair appropriate immune response, such as obesity.

OBJECTIVES

The aim of this study is to describe the manifestation, clinical course, and inflammatory biomarker milieu of COVID-19 in patients with obesity.

SETTING

University Hospital Philadelphia, Pennsylvania.

METHODS

In this retrospective cohort study, 600 patients who were positive for COVID-19 were stratified by World Health Organization (WHO) obesity class and their presenting symptoms, disease biomarkers, demographics, and outcomes (intubation rate, intensive care unit [ICU] admission, length of stay [LOS], and mortality) were investigated.

RESULTS

Age was inversely related to obesity class; patients of obesity class III presented 12.9 years younger than patients of normal weight (P < .0001). Initial ferritin lab values were negatively correlated with increasing obesity class (P = .0192). Normal or near-normal lymphocyte profile was noted in patients with obesity compared with patients without obesity (P = .0017). Patients with obesity had an increased rate of ICU admission (P = .0215) and increased length of stay (P = .0004), but no differences in intubation rate (P = .3705) or mortality (P = .2486).

CONCLUSION

Patients with obesity were more likely to present to the hospital at a younger age, with reduced levels of COVID-19 related biomarker disturbances, and increased LOS and ICU admission rates, although were not at increased risk for mortality.

Effect of Combined Interval and Continuous Exercise Training on Gastric Emptying, Appetite, and Adaptive Responses in Men With Overweight and Obesity

Background/Objectives: Characterizing compensatory and adaptive responses to exercise assists in understanding changes in energy balance and health outcomes with exercise interventions. This study investigated the effects of a short-term exercise intervention (combining high intensity interval (HII) and continuous exercise) on (1) gastric emptying, appetite and energy intake; and (2) other adaptive responses including cardiorespiratory fitness, in inactive men with overweight/obesity. Methods: Fifteen men (BMI: 29.7 ± 3.3 kg/m^-2) completed a 4-wk supervised exercise intervention, consisting of 5 exercise sessions per week alternating between HII (30 s at 100% VO₂max followed by 30 s recovery) and continuous (at 50% VO₂max) training on a cycle ergometer, progressing from 30 to 45 min session duration. Gastric emptying (¹³C-octanoic acid breath test), appetite (visual analog scale), energy intake (ad libitum lunch meal), body composition (air displacement plethysmography), non-exercise activity (accelerometery) VO₂max, blood pressure, and fasting concentrations of glucose, insulin, and ghrelin were measured before and after (≥48 h) the intervention. Results: Gastric emptying, glucose, insulin and ghrelin were unchanged, but energy intake at the ad libitum lunch test meal significantly increased at post-intervention (+171 ± 116 kcal, p < 0.01). Body weight (-0.9 ± 1.1 kg), waist circumference (-2.3 ± 3.5 cm) and percent body fat (-0.9 ± 1.1%) were modestly reduced (P < 0.05). VO₂max increased (+4.4 ± 2.1 ml.kg.min^-1) by 13% and systolic (-6.2 ± 8.4 mmHg) and diastolic (-5.8 ± 2.2 mmHg) blood pressure were significantly reduced (P ≤ 0.01 for all). Conclusions: Four weeks of exercise training did not alter gastric emptying, indicating gastric emptying may only adapt to a higher volume/longer duration of exercise or changes in other characteristics associated with regular exercise. The combination of HII and continuous exercise training had beneficial effects on body composition, cardiorespiratory fitness, and blood pressure and warrants further investigation in larger randomized controlled trials.

Methods to develop figure rating scales (FRS): A systematic review

BACKGROUND AND AIMS

Figure Rating Scales (FRS) are psychometric instruments developed to measure individual's perception of physical appearance and subsequently, to determine the level of body dissatisfaction. The following systematic review summarizes existing FRSs and the techniques used to development them.

METHODS

A systematic search was conducted in the following databases; PubMed®, Web of Science®, Scopus® using key words "figure rating scale" AND "Stunkard".

RESULTS

From 466 potentially relevant articles, 24 publications were included, 22 publications reporting original FRSs with the other two scales being modifications of the original for children and babies. Fifteen were figural drawings or silhouettes and nine were developed by photographic techniques, video methods or using computer software. Most of the figural scales were applicable for adults and consisted of nine images. Ten of the 15 figural scales were without facial features and four scales had minimal facial features. Technological advancements including 3D modeling have played a pivotal role in the development of FRSs.

CONCLUSIONS

FRSs have been developed by a mix of traditional and modern techniques. The development and validation of ethnic specific FRSs using modern technology should be the priority for future studies.

Glycemic and cardiometabolic effects of exercise in South Asian Sri Lankans with type 2 diabetes mellitus: A randomized controlled trial Sri Lanka diabetes aerobic and resistance training study (SL-DARTS)

BACKGROUND AND AIMS

To examine the effects of aerobic training (AT) and resistance training (RT) compared to standard care on glycemic control in South Asian Sri Lankan adults with Type 2 Diabetes Mellitus (T2DM).

METHODS

Randomized controlled trial (RCT) with parallel-group design recruited 86 sedentary Sri Lankans (aged 35-65 years) with T2DM into aerobic training (AT, n = 28), resistance training (RT, n = 28) and control (CN, n = 30) groups. Supervised progressive exercise training consisting of 75 min per session, 2 days per week for 12 weeks was conducted. The primary outcome was pre- and post-intervention absolute change in hemoglobin A1c (HBA1c). Secondary outcomes were serum lipids, liver enzymes, chronic inflammatory status, anthropometry, body composition and blood pressure.

RESULTS

The absolute change in HbA1c of RT vs. CN was -0.08% (95% CI, 0.8% to -0.7%, p = 0.8) and AT vs. CN was -0.22% (95% CI, 0.95% to -0.5%). Subgroup analysis (n = 49) with a high baseline HbA1c (>7.5%), absolute reduction in HbA1c in exercise groups were statistically significant (RT vs. CN was -0.37%; 95% CI 1.3% to -0.6%, p = 0.04 and AT vs. CN was -0.57%; 95% CI 1.7% to -0.6%, p = 0.03). The effect sizes (total and subgroup HbA1c >7.5%) ranged from 0.7 to 1.0 in AT, 0.4 to 1.1 in RT compared to 0.35 to 0.6 for the CN. Secondary outcomes did not significantly differ among groups.

CONCLUSIONS

Exercise training 2 days/week improved glycemic control in Sri Lankan adults with T2DM and the effects were significant in high baseline HbA1c (>7.5%) groups (RT > AT).

High intensity interval training does not result in short- or long-term dietary compensation in cardiac rehabilitation: Results from the FITR heart study

The aim of this study was to investigate short- and long-term compensatory effects on dietary intake following high intensity interval training (HIIT) compared with usual care moderate intensity continuous training (MICT) during and following a cardiac rehabilitation program. This study investigates secondary outcomes of a clinical trial. Ninety-three participants with coronary artery disease enrolled in a 4-week cardiac rehabilitation program, were randomised to 1) 4x4-minute HIIT; or 2) 40-min of MICT (usual care). Patients were instructed to complete 3 weekly sessions (2 supervised, 1 home-based) for 4-weeks, and 3 weekly home-based sessions thereafter for another 48-weeks. Dietary intake was measured by telephone-based 24-h recall over 2 day at baseline, 4-weeks, 3-months, 6-months, and 12-months. Three-Factor Eating Questionnaire was used to measure dietary behaviour and Leeds Food Preference Questionnaire used to measure food preferences. Appetite was assessed by a visual analogue scale and appetite-regulating hormones. There was no change over the study period or differences between groups for daily energy intake at 4-weeks or 12-months. There were also no group differences for any other measures of dietary intake, fasting hunger or appetite-related hormones, dietary behaviour, or food preferences. These findings suggest that compared to moderate intensity exercise, HIIT does not result in compensatory increases of energy intake or indicators of poor diet quality. This finding appears to be the same for patients with normal weight and obesity. HIIT can therefore be included in cardiac rehabilitation programs as an adjunct or alterative to MICT, without concern for any undesirable dietary compensation.

Sensory Profile of Adults with Reduced Food Intake and the Potential Roles of Nutrition and Physical Activity Interventions

The sensory profile, referring to sight, smell, taste, hearing, and touch, plays an essential role in optimizing the habitual intake of energy and macronutrients. However, specific populations, such as older adults, are known to have impaired energy intake. In this paper, the relevance of sensory impairments in this older population is described, and the extent to which nutritional and physical activity interventions can modulate these sensory responses when food intake is insufficient is explored. With aging, all senses deteriorate, and in most cases, such deteriorations diminish the nutritional response. The only exception is sight, for which both positive and negative impacts on nutritional response have been reported. From a prevention perspective, nutritional interventions have been understudied, and to date, only hearing is known to be positively affected by a good nutritional profile. In comparison, physical activity has been more frequently studied in this context, and is linked to an improved preservation of 4 senses. Regarding treatment, very few studies have directly targeted sensory training, and the focus of research has tended to be on nutrition and physical activity intervention. Sensory training, and nutritional and physical activity treatments all have beneficial effects on the senses. In the future, researchers should focus on exploring gaps in the literature specifically concerning prevention, treatment, and sensory response to understand how to improve the efficacy of current approaches. In order to maintain sensory acuity and recover from sensory impairment, the current state of knowledge supports the importance of improving nutritional habits as well as physical activity early on in life. A combined approach, linking a detailed lifestyle profile with the assessment of numerous senses and one or more interventional approaches (nutrition, physical activity, sensory training, etc.), would be required to identify effective strategies to improve the nutritional state of older individuals.

The Impact of Interdisciplinary Education on Skills and Attitudes of Surgery and Emergency Medicine Residents

Background  Interdisciplinary education (IDE) has been proposed as a means to improve patient safety by enhancing the performance of diverse health care teams. The improved camaraderie between members of different specialties may enhance communication and can foster a more supportive and positive work environment.

Objective  This study was aimed to assess the effect of IDE on the procedural skills of general surgery (GS) and emergency medicine (EM), as well as the perceptions that GS and EM residents have of one another.

Methods  EM and GS residents participated in two separate IDE sessions (4 months apart) designed to teach extended focused assessment with sonography in trauma (e-FAST), tube thoracostomy, and complex wound closure. Surveys were administered to determine the effects that IDE had on confidence in performing bedside procedures, perceptions of IDE, and perceptions of one another's specialty. Survey responses were recorded using a 5-point Likert's scale.

Results  Nine GS residents and 10 EM residents participated in the entire study. Significant improvements in the confidence levels of performing bedside procedures were noted among both groups of residents. We also report a significant improvement in the perceived respect and communication between EM and GS residents.

Conclusions  Although further studies with a larger sample size are required, we have shown that IDE can improve the confidence levels of EM and GS residents in performing tube thoracostomy, e-FAST, and complex wound closure. These IDE sessions also improve the perceptions that the residents have of one another. IDE is a useful tool and may translate into improved consultation, collaboration, and patient care.

A dual-process psychobiological model of temperament predicts liking and wanting for food and trait disinhibition

A dual-process model of temperament, incorporating the Behavioural Inhibition System (BIS), Behavioural Activation System (BAS) and effortful control (EC), may help to predict hedonic responses to palatable food and trait disinhibition.

PURPOSE

This study aimed to determine if the BIS, BAS and EC predicted liking and wanting for high-fat, sweet foods in adults with overweight and obesity, and if collectively, these variables predicted the eating behaviour trait of Disinhibition.

METHODS

168 adults (104 females, mean BMI = 33.3 kg/m²) completed the Three Factor Eating Questionnaire, the Carver and White BIS/BAS scales, the Adult Temperament Questionnaire-Effortful Control Scale - Short Form and the Leeds Food Preference Questionnaire. The strength of the BIS, BAS and EC in predicting wanting and liking for high-fat sweet foods, and trait Disinhibition was assessed using hierarchical multiple regression.

RESULTS

Both the BIS and EC predicted liking, F (6, 161) = 5.05, p < .001, R² = 0.16, and EC inversely predicted wanting, F (6, 161) = 3.28, p = .005, R² = 0.11. The BIS, EC and liking predicted, F (8, 159) = 11.0, p < .001, R² = 0.36, and explained 36% of Disinhibition. The BAS did not predict wanting, liking or Disinhibition.

CONCLUSIONS

These results demonstrate that a sensitive BIS and a lower level of effortful control predicts food reward and Disinhibition in overweight and obese adults. Consequently, interventions that aim to increase effortful control and reduce BIS reactivity may be beneficial for reducing hedonically motivated, disinhibited eating behaviour.

The feasibility and acceptability of morning versus evening exercise for overweight and obese adults: A randomized controlled trial

Background

The time of day that people exercise could have an influence on the efficacy of exercise for weight loss, via differences in adherence and/or physiological adaptations. However, there is currently no evidence to support an optimal time of day for exercise to maximise efficacy.

Purpose

To examine the feasibility and acceptability of prescribed morning and evening exercise.

Methods

Twenty inactive, overweight adults aged 18–60 years were recruited for a 12-week intervention and randomized to one of three groups using a 2:2:1 random allocation ratio: i) morning exercise (AM; n = 9); ii) evening exercise (PM; n = 7); or iii) waitlist control (CON; n = 4). Exercise groups were prescribed self-paced walking or running on a treadmill to achieve a weekly total of 250 min. Feasibility and acceptability data were collected, and physiological and behavioural outcomes associated with energy balance were measured at baseline, mid- and post-intervention.

Results

Attrition was low (n = 2 dropped out), with high measurement completion rates (>80%). The intervention groups had high adherence rates to exercise sessions (94% and 87% for the AM and PM groups, respectively). No adverse events resulting from the intervention were reported. Both intervention groups displayed improvements to their cardiometabolic risk profile; cardiorespiratory fitness improved by 5.2 ± 4.7, and 4.6 ± 4.5 mL kg⁻¹.min⁻¹ and body fat percentage reduced by 1.2 ± 1.4, and −0.6 ± 1.2% for AM and PM groups, respectively.

Conclusion

This feasibility study provides evidence that morning and evening exercise interventions are feasible, and also provides justification for a large-scale randomized controlled trial.

Trial registration

This trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616000457448p, 7/4/2016).

Are increases in skeletal muscle mass accompanied by changes to resting metabolic rate in rugby athletes over a pre-season training period?

Optimising dietary energy intake is essential for effective sports nutrition practice in rugby athletes. Effective dietary energy prescription requires careful consideration of athletes' daily energy expenditure with the accurate prediction of resting metabolic rate (RMR) important due to its influence on total energy expenditure and in turn, energy balance. This study aimed to (a) measure rugby athletes RMR and (b) report the change in RMR in developing elite rugby players over a rugby preseason subsequent to changes in body composition and (c) explore the accurate prediction of RMR in rugby athletes. Eighteen developing elite rugby union athletes (age 20.2 ± 1.7 years, body mass 101.2 ± 14.5 kg, stature 184.0 ± 8.4 cm) had RMR (indirect calorimetry) and body composition (dual energy x-ray absorptiometry) measured at the start and end of a rugby preseason ∼14 weeks later. There was no statistically significant difference in RMR over the preseason period (baseline 2389 ± 263 kcal·day^-1 post 2373 ± 270 kcal·day^-1) despite a significant increase in lean mass of +2.0 ± 1.6 kg (P < 0.01) and non-significant loss of fat mass. The change in RMR was non-significant and non-meaningful; thus, this study contradicts the commonly held anecdotal perception that an increase in skeletal muscle mass will result in a significant increase in metabolic rate and daily energy needs. Conventional prediction equations generally under-estimated rugby athletes' measured RMR, and may be problematic for identifying low energy availability, and thus updated population-specific prediction equations may be warranted to inform practice.

Rationale for novel intermittent dieting strategies to attenuate adaptive responses to energy restriction

Eating patterns involving intermittent energy restriction (IER) include 'intermittent fasting' where energy intake is severely restricted for several 'fasting' days per week, with 'refeeding' days (involving greater energy intake than during fasting days) at other times. Intermittent fasting does not improve weight loss compared to continuous energy restriction (CER), where energy intake is restricted every day. We hypothesize that weight loss from IER could be improved if refeeding phases involved restoration of energy balance (i.e. not ongoing energy restriction, as during intermittent fasting). There is some evidence in adults with overweight or obesity showing that maintenance of a lower weight may attenuate (completely or partially) some of the adaptive responses to energy restriction that oppose ongoing weight loss. Other studies show some adaptive responses persist unabated for years after weight loss. Only five randomized controlled trials in adults with overweight or obesity have compared CER with IER interventions that achieved energy balance (or absence of energy restriction) during refeeding phases. Two reported greater weight loss than CER, whereas three reported similar weight loss between interventions. While inconclusive, it is possible that achieving energy balance (i.e. avoiding energy restriction or energy excess) during refeeding phases may be important in realizing the potential of IER.

Measurement duration affects the calculation of whole body protein turnover kinetics but not between-day variability

BACKGROUND

Assessment of whole body protein turnover (WBPT) can provide fundamental information about protein kinetics which underpins the conservation of lean tissue. Reliability and methodology studies on the measurement of WBPT are scarce. This study aimed to assess the effects of urine collection duration (9 versus 12 h) and the reproducibility of WBPT with the end product method calculated from ammonia as the end product.

METHODS

WBPT was assessed in 21 healthy participants (11M, 10F) on 2 test days. WBPT was assessed using the end product method with a single dose of ¹⁵N glycine with ammonia as end product in a postprandial state with 9 and 12-h urine collections.

RESULTS

The CV for protein flux averaged 10% and 12% for 9 and 12-h urine collections respectively. Protein flux, synthesis and balance were significantly higher and protein breakdown significantly lower with 9-h urine collections compared to 12-h collections (P < 0.01) and there was a trend towards increasingly greater overestimation of 9-h calculated WBPT kinetics with greater overall rates of WBPT. Correlations between the 9 and 12-h values were strong (r > 0.962, P < 0.001 for all variables).

CONCLUSIONS

The reproducibility of WBPT with ammonia as the end product was similar to previously reported reproducibility of the gold standard precursor technique. The use of a 12-h urine collection is more effective to achieve full turnover of the ammonia free amino acid (AA) pool.

Study protocol: a randomised controlled trial of supervised resistance training versus aerobic training in Sri Lankan adults with type 2 diabetes mellitus: SL-DART study

Background

The prevalence of type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD) is rising globally. T2DM is particularly problematic in South Asia with an estimated 10–15% of Sri Lankans diagnosed with the disease. Exercise is known to improve blood glucose, lipid profiles, blood pressure and adiposity, key goals in the management of T2DM. However, much of the evidence to date has been gained from white Caucasians who have a different body composition and disease profile compared to South Asians. Similarly, the recreational exercise culture is new to Sri Lankans and the effects of exercise on T2DM has not been studied in this population.

Methods

The Sri Lanka Diabetes Aerobic and Resistance Training (SL-DART) Study will be comprised of 2 components. Component 1 is a 12-week randomized controlled trial (RCT) to compare the effects of a supervised progressive resistance exercise program (RT) and aerobic exercise program (AT) with standard treatment/control (CN). Sedentary Sri Lankan adults with T2DM (aged 35–65 years) and with no contraindications to exercise will be randomized into one of 3 groups (AT, RT, CN). Exercise sessions will be conducted 2 days/week for 3 months. Baseline and post-intervention biochemical (glycemic control, lipid and liver profiles, inflammatory markers), anthropometric (height, weight, body circumferences), body composition, physical fitness, food preference (liking and wanting food) and quality of life parameters will be measured and compared between groups. Component 2 will be a qualitative study conducted immediately post-intervention via in-depth interviews to assess the barriers and facilitators for adherence to each exercise program.

Discussion

SL-DART Study represents one of the first adequately powered methodologically sound RCTs conducted in South Asia to assess the effects of resistance and aerobic exercise in participants with T2DM. Triangulation of quantitative and qualitative outcomes will enable the design of a culturally appropriate therapeutic physical activity intervention for Sri Lankans with T2DM, and the initiation of a professionally driven and specialized clinical exercise prescription service.

Trial registration

Sri Lanka Clinical Trials Registry; SLCTR/2016/017. Date registered 17.06.2016. Universal trial number U1111–1181-7561.

Developing dimensions for a multicomponent multidisciplinary approach to obesity management: a qualitative study

BACKGROUND

There have been consistent recommendations for multicomponent and multidisciplinary approaches for obesity management. However, there is no clear agreement on the components, disciplines or processes to be considered within such an approach. In this study, we explored multicomponent and multidisciplinary approaches through an examination of knowledge, skills, beliefs, and recommendations of stakeholders involved in obesity management. These stakeholders included researchers, practitioners, educators, and patients.

METHODS

We used qualitative action research methods, including convergent interviewing and observation, to assist the process of inquiry.

RESULTS

The consensus was that a multicomponent and multidisciplinary approach should be based on four central meta-components (patient, practitioner, process, and environmental factors), and specific components of these factors were identified. Psychologists, dieticians, exercise physiologists and general practitioners were nominated as key practitioners to be included.

CONCLUSIONS

A complex condition like obesity requires that multiple components be addressed, and that both patients and multiple disciplines are involved in developing solutions. Implementing cycles of continuous improvement to deal with complexity, instead of trying to control for it, offers an effective way to deal with complex, changing multisystem problems like obesity.

Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study

Background/Objectives:

The MATADOR (Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound) study examined whether intermittent energy restriction (ER) improved weight loss efficiency compared with continuous ER and, if so, whether intermittent ER attenuated compensatory responses associated with ER.

Subjects/Methods:

Fifty-one men with obesity were randomised to 16 weeks of either: (1) continuous (CON), or (2) intermittent (INT) ER completed as 8 × 2-week blocks of ER alternating with 7 × 2-week blocks of energy balance (30 weeks total). Forty-seven participants completed a 4-week baseline phase and commenced the intervention (CON: N=23, 39.4±6.8 years, 111.1±9.1 kg, 34.3±3.0 kgm⁻²; INT: N=24, 39.8±9.5 years, 110.2±13.8 kg, 34.1±4.0 kgm⁻²). During ER, energy intake was equivalent to 67% of weight maintenance requirements in both groups. Body weight, fat mass (FM), fat-free mass (FFM) and resting energy expenditure (REE) were measured throughout the study.

Results:

For the N=19 CON and N=17 INT who completed the intervention per protocol, weight loss was greater for INT (14.1±5.6 vs 9.1±2.9 kg; P<0.001). INT had greater FM loss (12.3±4.8 vs 8.0±4.2 kg; P<0.01), but FFM loss was similar (INT: 1.8±1.6 vs CON: 1.2±2.5 kg; P=0.4). Mean weight change during the 7 × 2-week INT energy balance blocks was minimal (0.0±0.3 kg). While reduction in absolute REE did not differ between groups (INT: -502±481 vs CON: −624±557 kJ d⁻¹; P=0.5), after adjusting for changes in body composition, it was significantly lower in INT (INT: −360±502 vs CON: −749±498 kJ d⁻¹; P<0.05).

Conclusions:

Greater weight and fat loss was achieved with intermittent ER. Interrupting ER with energy balance ‘rest periods’ may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency.

A systematic review and meta-analysis of energy and macronutrient intake responses to physical activity interventions in children and adolescents with obesity

BACKGROUND

The effects of regular physical activity on energy intake in obese adolescents are unknown.

OBJECTIVE

The objective is to determine how physical activity interventions affect energy and macronutrient intake in overweight/obese youth.

DATA SOURCES

Databases were searched from December 2014 to December 2015 for studies that measured energy and/or macronutrient consumption in response to physical activity intervention in overweight/obese youth.

DATA SELECTION

The review comprises primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake before and after a physical activity intervention (without dietary restriction) in overweight or obese children and teenagers (up to 18 years old) were included. Of the initial 307 references found, nine were included.

RESULTS

The nine included studies analysed the effect of 15 different physical activity interventions. Nine showed a decrease and six unchanged energy intakes. The effect size for total energy intake ranged from -2.108 to -0.207 (n = 14). Results of the meta-analysis revealed a mean effect of physical intervention to reduce intake of -1.003 (95% confidence interval = -1.261 to -0.745, p < 0.001). Results for heterogeneity among these studies were I²  = 67.421; Q = 39.903; d_f  = 13, p < 0.001. The mean energy intake reduction was -323 ± 286 kcal. Macronutrient intake was assessed in 11 interventions. Protein intake was found decreased in five (reduction of -26.8 ± 19.2 g), seven reported fat decrease (reduction of -26.4 ± 17.8 g) and five a decrease in CHO (reduction of -72.5 ± 22.8 g). The meta-analysis revealed significant decreases of each macronutrient (p < 0.001).

CONCLUSION

Structured physical activity interventions favour decreased daily energy intake in obese adolescents.

Effect of moderate- and high-intensity acute exercise on appetite in obese individuals

PURPOSE

The effect of acute exercise, and exercise intensity, on appetite control in obese individuals requires further study. The aim of this study was to compare the effects of acute isocaloric bouts (250 kcal) of high-intensity intermittent cycling (HIIC) and moderate-intensity continuous cycling (MICC) or short-duration HIIC (S-HIIC) (125 kcal) and a resting control condition on the appetite hormone responses, subjective feelings of appetite, energy intake (EI), and food reward in overweight/obese individuals.

METHODS

This study is a randomized crossover study on 12 overweight/obese volunteers. Participants were assigned to the control, MICC, HIIC, and S-HIIC conditions, 1 wk apart, in a counterbalanced order. Exercise was performed 1 h after a standard breakfast. An ad libitum test lunch was served 3 h after breakfast. Fasting/postprandial plasma samples of insulin, acylated ghrelin, polypeptide YY3-36, and glucagon-like peptide 1 and subjective feelings of appetite were measured every 30 min for 3 h. Nutrient and taste preferences were measured at the beginning and end of each condition using the Leeds Food Preference Questionnaire.

RESULTS

Insulin levels were significantly reduced, and glucagon-like peptide 1 levels significantly increased during all exercise bouts compared with those during rest. Acylated ghrelin plasma levels were lower in the MICC and HIIC, but not in S-HIIC, compared with those in control. There were no significant differences for polypeptide YY3-36 plasma levels, hunger or fullness ratings, EI, or food reward.

CONCLUSIONS

Our findings suggest that, in overweight/obese individuals, isocaloric bouts of moderate- or high-intensity exercise lead to a similar appetite response. This strengthens previous findings in normal-weight individuals that acute exercise, even at high intensity, does not induce any known physiological adaptation that would lead to increased EI.

Acute exercise and gastric emptying: a meta-analysis and implications for appetite control

BACKGROUND

Gastric emptying (GE) could influence exercise-induced changes in appetite and energy intake. GE also could contribute to changes in gastric symptoms and the availability of nutrients during exercise, which will subsequently affect performance.

OBJECTIVE

The objective of this review was to determine the effects of acute exercise on GE using a systematic review and meta-analysis. The most common parameters to determine GE were selected, consisting of half-emptying time and volume emptied. Oral-caecal transit time (OCTT) was also examined.

DATA SOURCES

Research databases (PubMed, Scopus, Google Scholar, EBSCOhost, SPORTDiscus) were searched through November 2013 for original studies, abstracts, theses and dissertations that examined the influence of acute exercise on GE.

STUDY SELECTION

Studies were included if they evaluated GE or OCTT during and/or after exercise and involved a resting control trial.

STUDY APPRAISAL AND SYNTHESIS

Initially, 195 studies were identified. After evaluation of study characteristics and quality and validity, data from 20 studies (35 trials) involving 221 participants (157 men; 52 women; 12 unknown) were extracted for meta-analysis. Random-effects meta-analyses were utilised for the three main outcome variables, and effect sizes (ES) are reported as Hedge's g due to numerous small sample sizes.

RESULTS

Random-effects modelling revealed non-significant and small/null main effect sizes for volume emptied (ES = 0.195; 95% CI -0.25 to 0.64), half-time (ES = -0.109, 95% CI -0.66 to 0.44) and OCTT (ES = 0.089; 95% CI -0.64 to 0.82). All analyses exhibited significant heterogeneity and numerous variables moderated the results. There was a dose response of exercise intensity; at lower intensities GE was faster, and at high exercise intensities GE was slower. Walking was associated with faster GE and cycling with slower GE. Greater volume of meal/fluid ingested, higher osmolality of beverage and longer exercise duration were also associated with slower GE with exercise.

LIMITATIONS

The major limitation is that the majority of studies utilised a liquid bolus administered pre-exercise to determine GE; the relationship to post-exercise appetite and energy intake remains unknown. Study populations were also generally active or trained individuals. Furthermore, our review was limited to English language studies and studies that utilised resting control conditions.

CONCLUSIONS

These results suggest that exercise intensity, mode, duration and the nature of meal/fluid ingested all influence GE during and after acute exercise. The relationship of GE parameters with appetite regulation after exercise remains largely unexplored. Further integrative studies combining GE and alterations in gut hormones, as well as in populations such as overweight and obese individuals are needed.

Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials

Energy restriction induces physiological effects that hinder further weight loss. Thus, deliberate periods of energy balance during weight loss interventions may attenuate these adaptive responses to energy restriction and thereby increase the efficiency of weight loss (i.e. the amount of weight or fat lost per unit of energy deficit). To address this possibility, we systematically searched MEDLINE, PreMEDLINE, PubMed and Cinahl and reviewed adaptive responses to energy restriction in 40 publications involving humans of any age or body mass index that had undergone a diet involving intermittent energy restriction, 12 with direct comparison to continuous energy restriction. Included publications needed to measure one or more of body weight, body mass index, or body composition before and at the end of energy restriction. 31 of the 40 publications involved 'intermittent fasting' of 1-7-day periods of severe energy restriction. While intermittent fasting appears to produce similar effects to continuous energy restriction to reduce body weight, fat mass, fat-free mass and improve glucose homeostasis, and may reduce appetite, it does not appear to attenuate other adaptive responses to energy restriction or improve weight loss efficiency, albeit most of the reviewed publications were not powered to assess these outcomes. Intermittent fasting thus represents a valid--albeit apparently not superior--option to continuous energy restriction for weight loss.

Fasting gut hormone levels change with modest weight loss in obese adolescents

BACKGROUND

Gut hormones change with weight loss in adults but are not well studied in obese youth.

OBJECTIVE

The primary aim was to evaluate how gut hormones and subjective appetite measure change with dietary weight loss in obese adolescents.

METHODS

Participants were a subset of those taking part in the 'Eat Smart Study'. They were aged 10-17 years with body mass index (BMI) > 90th centile and were randomized to one of three groups: wait-listed control, structured reduced carbohydrate or structured low-fat dietary intervention for 12 weeks. Outcomes were fasting glucose, insulin, leptin, adiponectin, total amylin, acylated ghrelin, active glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP) and total peptide tyrosine-tyrosine. Pre- and postprandial subjective sensations of appetite were assessed using visual analogue scales.

RESULTS

Of 87 'Eat Smart' participants, 74 participated in this sub-study. The mean (standard deviation) BMI z-score was 2.1 (0.4) in the intervention groups at week 12 compared with 2.2 (0.4) in the control group. Fasting insulin (P = 0.05) and leptin (P = 0.03) levels decreased, while adiponectin levels increased (P = 0.05) in the intervention groups compared with control. The intervention groups were not significantly different from each other. A decrease in BMI z-score at week 12 was associated with decreased fasting insulin (P < 0.001), homeostatic model of assessment-insulin resistance (P < 0.001), leptin (P < 0.001), total amylin (P = 0.03), GIP (P = 0.01), PP (P = 0.02) and increased adiponectin (P < 0.001). There was no significant difference in appetite sensations.

CONCLUSIONS

Modest weight loss in obese adolescents leads to changes in some adipokines and gut hormones that may favour weight regain.

Psychological predictors of opportunistic snacking in the absence of hunger

Increased frequency of eating in the absence of homeostatic need, notably through snacking, is an important contributor to overconsumption and may be facilitated by increased availability of palatable food in the obesogenic environment. Opportunistic initiation of snacking is likely to be subject to individual differences, although these are infrequently studied in laboratory-based research paradigms. This study examined psychological factors associated with opportunistic initiation of snacking, and predictors of intake in the absence of homeostatic need. Fifty adults (mean age 34.5years, mean BMI 23.9kg/m(2), 56% female) participated in a snack taste test in which they ate a chocolate snack to satiation, after which they were offered an unanticipated opportunity to initiate a second eating episode. Trait and behavioural measures of self control, sensitivity to reward, dietary restraint and disinhibited eating were taken. Results showed that, contrary to expectations, those who initiated snacking were better at inhibitory control compared with those who did not initiate. However, amongst participants who initiated snacking, intake (kcal) was predicted by higher food reward sensitivity, impulsivity and BMI. These findings suggest that snacking initiation in the absence of hunger is an important contributor to overconsumption. Consideration of the individual differences promoting initiation of eating may aid in reducing elevated eating frequency in at-risk individuals.

The effect of a whey protein supplement dose on satiety and food intake in resistance training athletes

OBJECTIVE

Many athletes perform resistance training and consume dietary protein as a strategy to promote anabolic adaptation. Due to its high satiety value, the regular addition of supplemented dietary protein could plausibly displace other key macronutrients such as carbohydrate in an athlete's diet. This effect will be influenced by the form and dose of protein. Therefore, this study assessed the impact of liquid whey protein dose manipulation on subjective sensations of appetite and food intake in a cohort of athletes.

DESIGN

Ten male athletes who performed both resistance and aerobic (endurance) training (21.2 ± 2.3 years; 181.7 ± 5.7 cm and 80.8 ± 6.1 kg) were recruited. In four counter-balanced testing sessions they consumed a manipulated whey protein supplement (20, 40, 60 or 80 g protein) 1 hour after a standardised breakfast. Subsequent energy intake was measured 3 hours after the protein supplement using an ad libitum test meal. Subjective appetite sensations were measured periodically during the test day using visual analogue scales.

RESULTS

All conditions resulted in a significant decrease in ratings of hunger (50-65%; P < 0.05) at the time of supplement consumption. However, there were no significant differences between the conditions at any time point for subjective appetite sensations or for energy consumed in the ad libitum meal: 4382 ± 1004, 4643 ± 982, 4514 ± 1112, 4177 ± 1494 kJ respectively.

CONCLUSION

Increasing whey protein supplement dose above 20 g did not result in a measurable increase in satiety or decrease in food intake. However, the inclusion of additional whey protein supplementation where not otherwise consumed could plausibly reduce dietary intake.

Effect of a 4-week weight maintenance diet on circulating hormone levels: implications for clinical weight loss trials

The majority of weight loss studies fail to standardize conditions such as diet and exercise via a weight maintenance period prior to commencement of the trial. This study aimed to determine whether a weight stabilization period is necessary to establish stable baseline hormone concentrations. Fifty-one obese male participants with a body mass index of 30-40 kg m(-2) and aged 25-54 years underwent 4 weeks on an energy balance diet that was designed to achieve weight stability. Blood samples were collected in the fasting state at commencement and completion of the 4-week period, and circulating concentrations of 18 commonly measured hormones were determined. During the 4-week weight maintenance period, participants achieved weight stability within -1.5 ± 0.2 kg (-1.4 ± 0.2%) of their initial body weight. Significant reductions in serum insulin (by 18 ± 6.5%) and leptin (by 21 ± 6.0%) levels occurred, but no significant changes were observed for gut-derived appetite-regulating hormones (ghrelin and peptide YY), nor thyroid, adrenal, gonadal or somatotropic hormones. There were no significant correlations between the change in body weight and the change in circulating concentrations of insulin or leptin over the 4-week period, indicating that the observed changes were not due to weight loss, albeit significant negative correlations were observed between the changes in body weight and plasma ghrelin and peptide YY levels. This study demonstrates the need for baseline weight maintenance periods to stabilize serum levels of insulin and leptin in studies specifically investigating effects on these parameters in the obese. However, this does not apply to circulating levels of gut-derived appetite-regulating hormones (ghrelin and peptide YY), nor thyroid, adrenal, gonadal or somatotropic hormones.

Acute interval exercise intensity does not affect appetite and nutrient preferences in overweight and obese males

This study investigated the influence of two different intensities of acute interval exercise on food preferences and appetite sensations in overweight and obese men. Twelve overweight/obese males (age=29.0±4.1 years; BMI =29.1±2.4 kg/m2) completed three exercise sessions: an initial graded exercise test, and two interval cycling sessions: moderate-(MIIT) and high-intensity (HIIT) interval exercise sessions on separate days in a counterbalanced order. The MIIT session involved cycling for 5-minute repetitions of alternate workloads 20% below and 20% above maximal fat oxidation. The HIIT session consisted of cycling for alternate bouts of 15 seconds at 85% VO2max and 15 seconds unloaded recovery. Appetite sensations and food preferences were measured immediately before and after the exercise sessions using the Visual Analogue Scale and the Liking & Wanting experimental procedure. Results indicated that liking significantly increased and wanting significantly decreased in all food categories after both MIIT and HIIT. There were no differences between MIIT and HIIT on the effect on appetite sensations and Liking & Wanting. In conclusion, manipulating the intensity of acute interval exercise did not affect appetite and nutrient preferences.

Resistance to exercise-induced weight loss: compensatory behavioral adaptations

In many interventions that are based on an exercise program intended to induce weight loss, the mean weight loss observed is modest and sometimes far less than what the individual expected. The individual responses are also widely variable, with some individuals losing a substantial amount of weight, others maintaining weight, and a few actually gaining weight. The media have focused on the subpopulation that loses little weight, contributing to a public perception that exercise has limited utility to cause weight loss. The purpose of the symposium was to present recent, novel data that help explain how compensatory behaviors contribute to a wide discrepancy in exercise-induced weight loss. The presentations provide evidence that some individuals adopt compensatory behaviors, that is, increased energy intake and/or reduced activity, that offset the exercise energy expenditure and limit weight loss. The challenge for both scientists and clinicians is to develop effective tools to identify which individuals are susceptible to such behaviors and to develop strategies to minimize their effect.

Effect of chronic exercise on appetite control in overweight and obese individuals

PURPOSE

The effect of exercise on body mass is likely to be partially mediated through changes in appetite control. However, no studies have examined the effect of chronic exercise on obestatin and cholecystokinin (CCK) plasma concentrations or the sensitivity to detect differences in preload energy in obese individuals. The objective of this study was to investigate the effects of chronic exercise on 1) fasting and postprandial plasma concentrations of obestatin, CCK, leptin, and glucose insulinotropic peptide (GIP) and 2) the accuracy of energy compensation in response to covert preload manipulation.

METHODS

This study used a 12-wk supervised exercise program in 22 sedentary overweight/obese individuals. Fasting/postprandial plasma concentrations of obestatin, CCK, leptin, and GIP were assessed before and after the intervention. Energy compensation at a 30-min test meal after a high-energy (607 kcal) or a low-energy (246 kcal) preload and for the rest of the day (cumulative energy intake [EI]) was also measured.

RESULTS

There was a significant reduction in the plasma concentration of fasting plasma GIP and both fasting and postprandial leptin concentrations after the exercise intervention (P < 0.05 for all). No significant changes were observed for CCK or obestatin. A significant preload-exercise interaction (P = 0.011) was observed on cumulative EI and energy compensation for the same period (-87% ± 196% vs 68% ± 165%, P = 0.011). Weight loss (3.5 ± 1.4 kg, P < 0.0001) was not correlated with changes in energy compensation.

CONCLUSIONS

This study suggests that exercise improves the accuracy of compensation for previous EI, independent of weight loss. Unexpectedly, and in contrast to GIP and leptin, exercise-induced weight loss had no effect on obestatin or CCK concentrations.

Effect of interval training intensity on fat oxidation, blood lactate and the rate of perceived exertion in obese men

PURPOSE

The objectives of this study were to examine the effect of 4-week moderate- and high-intensity interval training (MIIT and HIIT) on fat oxidation and the responses of blood lactate (BLa) and rating of perceived exertion (RPE).

METHODS

Ten overweight/obese men (age = 29 ±3.7 years, BMI = 30.7 ±3.4 kg/m(2)) participated in a cross-over study of 4-week MIIT and HIIT training. The MIIT training sessions consisted of 5-min cycling stages at mechanical workloads 20% above and 20% below 45%VO2peak. The HIIT sessions consisted of intervals of 30-s work at 90%VO2peak and 30-s rest. Pre- and post-training assessments included VO2max using a graded exercise test (GXT) and fat oxidation using a 45-min constant-load test at 45%VO2max. BLa and RPE were also measured during the constant-load exercise test.

RESULTS

There were no significant changes in body composition with either intervention. There were significant increases in fat oxidation after MIIT and HIIT (p ≤ 0.01), with no effect of intensity. BLa during the constant-load exercise test significantly decreased after MIIT and HIIT (p ≤ 0.01), and the difference between MIIT and HIIT was not significant (p = 0.09). RPE significantly decreased after HIIT greater than MIIT (p ≤ 0.05).

CONCLUSION

Interval training can increase fat oxidation with no effect of exercise intensity, but BLa and RPE decreased after HIIT to greater extent than MIIT.

Reproducibility of gastric emptying in overweight and obese males

BACKGROUND & AIM

To understand whether any change in gastric emptying (GE) is physiologically relevant, it is important to identify its variability. Information regarding the variability of GE in overweight and obese individuals is lacking. The aim of this study was to determine the reproducibility of GE in overweight and obese males.

METHODS

Fifteen overweight and obese males [body mass index 30.3 (4.9) kg/m(2)] completed two identical GE tests 7 days apart. GE of a standard pancake breakfast was assessed by (13)C-octanoic acid breath test. Data are presented as mean (±SD).

RESULTS

There were no significant differences in GE between test days (half time (t1/2): 179 (15) and 176 (19 min), p = 0.56; lag time (tlag): 108 (14) and 104 (8) min, p = 0.26). Mean intra-individual coefficient of variation for t1/2 was 7.9% and tlag 7.5%. Based on these findings, to detect a treatment effect in a paired design with a power of 80% and α = 0.05, minimum mean effect sizes for t1/2 would need to be ≥14.4 min and tlag ≥ 8.1 min.

CONCLUSIONS

These data show that GE is reproducible in overweight and obese males and provide minimum mean effect sizes required to detect a hypothetical treatment effect in this population.

Relationships among tonic and episodic aspects of motivation to eat, gut peptides, and weight before and after bariatric surgery

BACKGROUND

The interaction between motivation to eat, eating behavior traits, and gut peptides after Roux-en-Y gastric bypass (RYGB) surgery is not fully understood.

METHODS

Appetite and hormone responses to a fixed liquid preload were assessed in 12 obese (body mass index 45 ± 1.9 kg/m(2)) participants immediately before and 3 days, 2 months, and 1 year after RYGB surgery. Subjective appetite and plasma levels of ghrelin, leptin, insulin, and glucagon-like peptide-1 (GLP-1) were measured for a 3-hour postprandial period. Eating behavior traits were also measured using the Three Factor Eating Questionnaire 18 (TFEQR18).

RESULTS

There was a decrease in TFEQR18 emotional eating (EE) and uncontrolled eating (UE) from presurgery to 1 year postsurgery but no significant change in cognitive restraint (CR). These changes occurred independently of change in weight. In addition, there was a reduction in subjective appetite ratings and alterations in appetite peptides favoring an anorectic response. Presurgery EE was significantly related to fasting and area under the curve (AUC) ghrelin; UE was associated with AUC desire to eat, and there was a significant association between fasting desire to eat and ghrelin (fasting and AUC). One year postsurgery, UE was positively related to fasting insulin, and CR was negatively associated with GLP-1. UE and subjective hunger were positively correlated, while the relationship between desire to eat and ghrelin remained.

CONCLUSION

The relationships among subjective appetite ratings, eating behavior traits, and appetite peptides in obese patients both before and at 1 year after RYGB surgery may contribute to the reduction in a propensity to overeat (as measured by TFEQR18 factors) and weight loss.

The effects of weight loss strategies on gastric emptying and appetite control

The gastrointestinal tract plays an important role in the improved appetite control and weight loss in response to bariatric surgery. Other strategies which similarly alter gastrointestinal responses to food intake could contribute to successful weight management. The aim of this review is to discuss the effects of surgical, pharmacological and behavioural weight loss interventions on gastrointestinal targets of appetite control, including gastric emptying. Gastrointestinal peptides are also discussed because of their integrative relationship in appetite control. This review shows that different strategies exert diverse effects and there is no consensus on the optimal strategy for manipulating gastric emptying to improve appetite control. Emerging evidence from surgical procedures (e.g. sleeve gastrectomy and Roux-en-Y gastric bypass) suggests a faster emptying rate and earlier delivery of nutrients to the distal small intestine may improve appetite control. Energy restriction slows gastric emptying, while the effect of exercise-induced weight loss on gastric emptying remains to be established. The limited evidence suggests that chronic exercise is associated with faster gastric emptying, which we hypothesize will impact on appetite control and energy balance. Understanding how behavioural weight loss interventions (e.g. diet and exercise) alter gastrointestinal targets of appetite control may be important to improve their success in weight management.

The relationship between substrate metabolism, exercise and appetite control: does glycogen availability influence the motivation to eat, energy intake or food choice?

The way in which metabolic fuels are utilized can alter the expression of behaviour in the interests of regulating energy balance and fuel availability. This is consistent with the notion that the regulation of appetite is a psychobiological process, in which physiological mediators act as drivers of behaviour. The glycogenostatic theory suggests that glycogen availability is central in eliciting negative feedback signals to restore energy homeostasis. Due to its limited storage capacity, carbohydrate availability is tightly regulated and its restoration is a high metabolic priority following depletion. It has been proposed that such depletion may act as a biological cue to stimulate compensatory energy intake in an effort to restore availability. Due to the increased energy demand, aerobic exercise may act as a biological cue to trigger compensatory eating as a result of perturbations to muscle and liver glycogen stores. However, studies manipulating glycogen availability over short-term periods (1-3 days) using exercise, diet or both have often produced equivocal findings. There is limited but growing evidence to suggest that carbohydrate balance is involved in the short-term regulation of food intake, with a negative carbohydrate balance having been shown to predict greater ad libitum feeding. Furthermore, a negative carbohydrate balance has been shown to be predictive of weight gain. However, further research is needed to support these findings as the current research in this area is limited. In addition, the specific neural or hormonal signal through which carbohydrate availability could regulate energy intake is at present unknown. Identification of this signal or pathway is imperative if a casual relationship is to be established. Without this, the possibility remains that the associations found between carbohydrate balance and food intake are incidental.

Exercise intensity influences nonexercise activity thermogenesis in overweight and obese adults

PURPOSE

The purpose of this study was to determine the effect of acute bouts of moderate- and high-intensity walking exercise on nonexercise activity thermogenesis (NEAT) in overweight and obese adults.

METHODS

Sixteen participants performed a single bout of either moderate-intensity walking exercise (MIE) or high-intensity walking exercise (HIE) on two separate occasions. The MIE consisted of walking for 60 min on a motorized treadmill at 6 km·h(-1). The 60-min HIE session consisted of walking in 5-min intervals at 6 km·h(-1) and 10% grade followed by 5 min at 0% grade. NEAT was assessed by accelerometer 3 d before, on the day of, and 3 d after the exercise sessions.

RESULTS

There was no significant difference in NEAT vector magnitude (counts per minute) between the preexercise period (days 1-3) and the exercise day (day 4) for either the MIE or the HIE protocol. In addition, there was no change in NEAT during the 3 d after the MIE session; however, NEAT increased by 16% on day 7 (postexercise) compared with the exercise day (P = 0.32). However, during the postexercise period after the HIE session, NEAT was increased by 25% on day 7 compared with the exercise day (P = 0.08) and by 30%-33% compared with the preexercise period (days 1, 2, and 3; P = 0.03, 0.03, and 0.02, respectively).

CONCLUSION

A single bout of either MIE or HIE did not alter NEAT on the exercise day or on the first 2 d after the exercise session. However, monitoring NEAT on a third day allowed the detection of a 48-h delay in increased NEAT after performing HIE. A longer-term intervention is needed to determine the effect of accumulated exercise sessions over a week on NEAT.

Acute and long-term effects of exercise on appetite control: is there any benefit for weight control?

PURPOSE OF REVIEW

To examine the relationship between energy intake, appetite control and exercise, with particular reference to longer term exercise studies. This approach is necessary when exploring the benefits of exercise for weight control, as changes in body weight and energy intake are variable and reflect diversity in weight loss.

RECENT FINDINGS

Recent evidence indicates that longer term exercise is characterized by a highly variable response in eating behaviour. Individuals display susceptibility or resistance to exercise-induced weight loss, with changes in energy intake playing a key role in determining the degree of weight loss achieved. Marked differences in hunger and energy intake exist between those who are capable of tolerating periods of exercise-induced energy deficit, and those who are not. Exercise-induced weight loss can increase the orexigenic drive in the fasted state, but for some this is offset by improved postprandial satiety signalling.

SUMMARY

The biological and behavioural responses to acute and long-term exercise are highly variable, and these responses interact to determine the propensity for weight change. For some people, long-term exercise stimulates compensatory increases in energy intake that attenuate weight loss. However, favourable changes in body composition and health markers still exist in the absence of weight loss. The physiological mechanisms that confer susceptibility to compensatory overconsumption still need to be determined.

Ghrelin and obestatin concentrations during puberty: relationships with adiposity, nutrition and physical activity

Ghrelin and obestatin are two peptides associated with appetite control and the regulation of energy balance in adults. It is intuitive that they have an important role in growth and development during puberty. Therefore, it is acknowledged that these peptides, in addition to others, form part of the substrate underlying energy homeostasis which in turn will contribute to body weight regulation and could explain changes in energy balance during puberty. Both peptides originate from the stomach; hence, it is intuitive that they are involved in generating signals from tissue stores which influence food intake. This could be manifested via alterations in the drive to eat (i.e. hunger), eating behaviors and appetite regulation. Furthermore, there is some evidence that these peptides might also be associated with physical activity behaviors and metabolism. Anecdotally, children and adolescents experience behavioral and metabolic changes during growth and development which will be associated with physiological changes.

Resistance training for obese, type 2 diabetic adults: a review of the evidence

In both developed and developing countries, increased prevalence of obesity has been strongly associated with increased incidence of type 2 diabetes mellitus (T2DM) in the adult population. Previous research has emphasized the importance of physical activity in the prevention and management of obesity and T2DM, and generic exercise guidelines originally developed for the wider population have been adapted for these specific populations. However, the guidelines traditionally focus on aerobic training without due consideration to other exercise modalities. Recent reviews on resistance training in the T2DM population have not compared this modality with others including aerobic training, or considered the implications of resistance training for individuals suffering from both obesity and T2DM. In short, the optimal mix of exercise modalities in the prescription of exercise has not been identified for it benefits to the metabolic, body composition and muscular health markers common in obesity and T2DM. Similarly, the underlying physical, social and psychological barriers to adopting and maintaining exercise, with the potential to undermine the efficacy of exercise interventions, have not been addressed in earlier reviews. Because it is well established that aerobic exercise has profound effects on obesity and T2DM risk, the purpose of this review was to address the importance of resistance training to obese adults with T2DM.

Exercise-induced energy expenditure: implications for exercise prescription and obesity

OBJECTIVE

Walking is commonly recommended to help with weight management. We measured total energy expenditure (TEE) and its components to quantify the impact of increasing exercise-induced energy expenditure (ExEE) on other components of TEE.

METHODS

Thirteen obese women underwent an 8-week walking group intervention. TEE was quantified using doubly labeled water, ExEE was quantified using heart rate monitors, daily movement was assessed by accelerometry and resting metabolic rate was measured using indirect calorimetry.

RESULTS

Four of the 13 participants achieved the target of 1500kcalwk(-1) of ExEE and all achieved 1000kcalwk(-1). The average ExEE achieved by the group across the 8 weeks was 1434+/-237kcalwk(-1). Vigorous physical activity, as assessed by accelerometry, increased during the intervention by an average of 30min per day. Non-exercise activity thermogenesis (NEAT) decreased, on average, by 175kcald(-1) (-22%) from baseline to the intervention and baseline fitness was correlated with change in NEAT.

CONCLUSIONS

Potential alterations in non-exercise activity should be considered when exercise is prescribed. The provision of appropriate education on how to self-monitor daily activity levels may improve intervention outcomes in groups who are new to exercise.

PRACTICE IMPLICATIONS

Strategies to sustain incidental and light physical activity should be offered to help empower individuals as they develop and maintain healthy and long-lasting lifestyle habits.

Vo2max in overweight and obese adults: do they meet the threshold criteria?

PURPOSE

The purpose of this study was to determine whether adiposity affects the attainment of (.)VO2max.

METHODS

Sixty-seven male and 68 female overweight (body mass index (BMI) = 25-29.9 kg.m) and obese (BMI > or = 30 kg x m) participants undertook a graded treadmill test to volitional exhaustion (phase 1) followed by a verification test (phase 2) to determine the proportion who could achieve a plateau in (.)VO2 and other "maximal" markers (RER, lactate, HR, RPE).

RESULTS

At the end of phase 1, 46% of the participants reached a plateau in (.)VO2, 83% increased HR to within 11 beats of age-predicted maximum, 89% reached an RER of > or = 1.15, 70% reached a blood lactate concentration of > or = 8 mmol x L, and 74% reached an RPE of > or = 18. No significant differences between genders and between BMI groups were found with the exception of blood lactate concentration (males = 84% vs females = 56%, P < 0.05). Neither gender nor fatness predicted the number of other markers attained, and attainment of other markers did not differentiate whether a (.)VO2 plateau was achieved. The verification test (phase 2) revealed that an additional 52 individuals (39%) who did not exhibit a plateau in (.)VO2 in phase 1 had no further increase in (.)VO2 in phase 2 despite an increase in workload.

CONCLUSIONS

These findings indicate that the absence of a plateau in (.)VO2 alone is not indicative of a failure to reach a true maximal (.)VO2 and that individuals with excessive body fat are no less likely than "normal-weight" individuals to exhibit a plateau in (.)VO2 provided that the protocol is appropriate and encouragement to exercise to maximal exertion is provided.