Exercise, Appetite Control, and Body Weight Regulation

Exercise has many health benefits and should be an effective weight loss strategy because it increases energy expenditure. However, the success of exercise in producing and sustaining weight loss is influenced by compensatory changes in energy intake and non-exercise activity, among other factors (see King et al. Obesity 15(6):1373–1383, 2007 for a detailed review). The aim of this chapter is to discuss the evidence describing the relationship between exercise and body weight regulation, with a particular focus on appetite control. Evidence is discussed which demonstrates that weight loss responses to exercise are highly variable between individuals. The mechanisms underlying the relationship between exercise, appetite and energy intake, and hence body weight are also discussed. Some people experience an increase in fasting hunger in response to 12 weeks of supervised exercise. However, this is offset by an increase in meal-related satiety in overweight and obese individuals. It is worth noting that weight loss should not be considered as the only successful outcome of an exercise program. Indeed, exercise, even in the absence of weight loss, is associated with numerous health benefits. Nevertheless, an improved understanding of compensatory responses to exercise is vital so that exercise can be more effectively used in weight management; such an understanding may assist us to devise strategies to sustain greater long-term participation in physical activity.

Maternal pregravid body mass index and child hospital admissions in the first 5 years of life: results from an Australian birth cohort

Objectives: To examine the association of maternal pregravid body mass index (BMI) and child offspring, all-cause hospitalisations in the first 5 years of life. Methods: Prospective birth cohort study. From 2006 to 2011, 2779 pregnant women (2807 children) were enrolled in the Environments for Healthy Living: Griffith birth cohort study in South-East Queensland, Australia. Hospital delivery record and self-report baseline survey of maternal, household and demographic factors during pregnancy were linked to the Queensland Hospital Admitted Patients Data Collection from 1 November 2006 to 30 June 2012, for child admissions. Maternal pregravid BMI was classified as underweight (<18.5 kg m−2), normal weight (18.5–24.9 kg m−2), overweight (25.0–29.9 kg m−2) or obese (30 kg m−2). Main outcomes were the total number of child hospital admissions and ICD-10-AM diagnostic groupings in the first 5 years of life. Negative binomial regression models were calculated, adjusting for follow-up duration, demographic and health factors. The cohort comprised 8397.9 person years (PYs) follow-up. Results: Children of mothers who were classified as obese had an increased risk of all-cause hospital admissions in the first 5 years of life than the children of mothers with a normal BMI (adjusted rate ratio (RR) =1.48, 95% confidence interval 1.10–1.98). Conditions of the nervous system, infections, metabolic conditions, perinatal conditions, injuries and respiratory conditions were excessive, in both absolute and relative terms, for children of obese mothers, with RRs ranging from 1.3–4.0 (PYs adjusted). Children of mothers who were underweight were 1.8 times more likely to sustain an injury or poisoning than children of normal-weight mothers (PYs adjusted). Conclusion: Results suggest that if the intergenerational impact of maternal obesity (and similarly issues related to underweight) could be addressed, a significant reduction in child health care use, costs and public health burden would be likely.

Reproducibility of fatmax and fat oxidation rates during exercise in recreationally trained males

Aerobic exercise training performed at the intensity eliciting maximal fat oxidation (Fatmax) has been shown to improve the metabolic profile of obese patients. However, limited information is available on the reproducibility of Fatmax and related physiological measures. The aim of this study was to assess the intra-individual variability of: a) Fatmax measurements determined using three different data analysis approaches and b) fat and carbohydrate oxidation rates at rest and at each stage of an individualized graded test. Fifteen healthy males [body mass index 23.1±0.6 kg/m2, maximal oxygen consumption () 52.0±2.0 ml/kg/min] completed a maximal test and two identical submaximal incremental tests on ergocycle (30-min rest followed by 5-min stages with increments of 7.5% of the maximal power output). Fat and carbohydrate oxidation rates were determined using indirect calorimetry. Fatmax was determined with three approaches: the sine model (SIN), measured values (MV) and 3rd polynomial curve (P3). Intra-individual coefficients of variation (CVs) and limits of agreement were calculated. CV for Fatmax determined with SIN was 16.4% and tended to be lower than with P3 and MV (18.6% and 20.8%, respectively). Limits of agreement for Fatmax were −2±27% of with SIN, −4±32 with P3 and −4±28 with MV. CVs of oxygen uptake, carbon dioxide production and respiratory exchange rate were <10% at rest and <5% during exercise. Conversely, CVs of fat oxidation rates (20% at rest and 24–49% during exercise) and carbohydrate oxidation rates (33.5% at rest, 8.5–12.9% during exercise) were higher. The intra-individual variability of Fatmax and fat oxidation rates was high (CV>15%), regardless of the data analysis approach employed. Further research on the determinants of the variability of Fatmax and fat oxidation rates is required.

Comparing fat oxidation in an exercise test with moderate-intensity interval training

This study compared fat oxidation rate from a graded exercise test (GXT) with a moderate-intensity interval training session (MIIT) in obese men. Twelve sedentary obese males (age 29 ± 4.1 years; BMI 29.1 ± 2.4 kg·m-2; fat mass 31.7 ± 4.4 %body mass) completed two exercise sessions: GXT to determine maximal fat oxidation (MFO) and maximal aerobic power (VO2max), and an interval cycling session during which respiratory gases were measured. The 30-min MIIT involved 5-min repetitions of workloads 20% below and 20% above the MFO intensity. VO2max was 31.8 ± 5.5 ml·kg-1·min-1 and all participants achieved ≥ 3 of the designated VO2max test criteria. The MFO identified during the GXT was not significantly different compared with the average fat oxidation rate in the MIIT session. During the MIIT session, fat oxidation rate increased with time; the highest rate (0.18 ± 0.11 g·min- 1) in minute 25 was significantly higher than the rate at minute 5 and 15 (p ≤ 0.01 and 0.05 respectively). In this cohort with low aerobic fitness, fat oxidation during the MIIT session was comparable with the MFO determined during a GXT. Future research may consider if the varying workload in moderate-intensity interval training helps adherence to exercise without compromising fat oxidation.

Long-term growth and anthropometry after childhood liver transplantation

Objectives: To describe longitudinal height, weight, and body mass index changes up to 15 years after childhood liver transplantation. Study design: Retrospective chart review of patients who underwent liver transplant from 1985-2004 was performed. Subjects were age <18 years at transplant, survived ≥5 years, with at least 2 recorded measurements, of which one was ≥5 years post-transplant. Measurements were recorded pre-transplant, 1, 5, 10, and 15 years later. Results: Height and weight data were available in 98 and 104 patients, respectively; 47% were age <2 years at transplant; 58% were Australian, and the rest were from Japan. Height recovery continued for at least 10 years to reach the 26th percentile (Z-score -0.67) 15 years after transplant. Australians had better growth recovery and attained 47th percentile (Z-score -0.06) at 15 years. Weight recovery was most marked in the first year and continued for 15 years even in well-nourished children. Growth impaired and malnourished children at transplant exhibited the best growth, but remained significantly shorter and lighter even 15 years later. No effect of sex or age at transplant was noted on height or weight recovery. Post-transplant factors significantly impact growth recovery and likely caused the dichotomous growth recovery between Australian and Japanese children; 9% (9/98) of patients were overweight on body mass index calculations at 10-15 years but none were obese. Conclusions: After liver transplant, children can expect ongoing height and weight recovery for at least 10-15 years. Growth impairment at transplant and post-transplant care significantly impact long-term growth recovery. Copyright © 2013 Mosby Inc. All rights reserved.

Randomised clinical trial of a family-based lifestyle intervention for childhood obesity involving parents as the exclusive agents of change

Parent-centred interventions for childhood obesity aim to improve parents' skills and confidence in managing children's dietary and activity patterns, and in promoting a healthy lifestyle in their family. However, few studies assess changes in parenting over the course of treatment. This study describes the evaluation of a lifestyle-specific parenting program (Group Lifestyle Triple P) on multiple child and parent outcomes. One-hundred-and-one families with overweight and obese 4- to 11-year-old children participated in an intervention or waitlist control condition. The 12-week intervention was associated with significant reductions in child BMI z score and weight-related problem behaviour. At the end of the intervention, parents reported increased confidence in managing children's weight-related behaviour, and less frequent use of inconsistent or coercive parenting practices. All short-term intervention effects were maintained at one-year follow-up assessment, with additional improvements in child body size. The results support the efficacy of Group Lifestyle Triple P and suggest that parenting influences treatment outcomes. Further research is needed to evaluate the long-term effectiveness of the intervention and to elucidate the mechanisms of change. © 2010 Elsevier Ltd.

Validity of currently used cutoff values of body mass index as a measure of obesity in Sri Lankan children

The aim of the study was to determine the reliability of body mass index based (BMI) cutoff values in diagnosing obesity among Sri Lankan children. Height, weight, waist circumference (WC) and hip circumference (HC) in 282 children were measured. Total body water was determined by deuterium dilution and fat mass (FM) derived using age and gender specific constants. A percentage FM of 30% for girls and 25% for boys were considered as cutoff levels for obesity. Two hundred and eighty two children (M/F: 158/124) were studied and 99 (80%) girls and 72 (45.5%) boys were obese based on % body fat. Eight (6.4%) girls and nine (5.7%) boys were obese based on International Obesity Task Force (IOTF) cutoff values. Percentage FM and WC centile charts were able to diagnose a significant proportion of children as true obese children. The FM and BMI were closely associated in both girls (r = 0.82, p < 0.001) and boys (r = 0.87, p < 0.001). Percentage FM and BMI had a very low but significant association; girls (r = 0.32, p < 0.001) and boys (r = 0.68, p < 0.001). FM had a significant association with WC and HC. BMI based cutoff values had a specificity of 100% but a very low sensitivity, varying between 8% and 23.6%. BMI is a poor indicator of the percentage fat and the commonly used cutoff values were not sensitive to detect cases of childhood obesity in Sri Lankan children.

Impaired physical function associated with childhood obesity: How should we intervene?

- Background This study examined relationships between adiposity, physical functioning and physical activity. - Methods Obese (N=107) and healthy-weight (N=132) children aged 10-13 years underwent assessments of percent body fat (%BF, dual energy X-ray absorptiometry), knee extensor strength (KE, isokinetic dynamometry), cardiorespiratory fitness (CRF, peak oxygen uptake by cycle ergometry), physical health-related quality of life (HRQOL), worst pain intensity and walking capacity [six-minute walk (6MWT)]. Structural equation modelling was used to assess relationships between variables. - Results Moderate relationships were observed between %BF and 6MWT, KE strength corrected for mass and CRF relative to mass (r -.36 to -.69, P≤.007). Weak relationships were found between: %BF and physical HRQOL (r -.27, P=.008); CRF relative to mass and physical HRQOL (r -.24, P=.003); physical activity and 6MWT (r .17, P=.004). Squared multiple correlations showed that 29.6% variance in physical HRQOL was explained by %BF, pain and CRF relative to mass, while 28% variance in 6MWT was explained by %BF and physical activity. - Conclusions It appears that children with a higher body fat percentage have poorer KE strength, CRF and overall physical functioning. Reducing percent fat appears to be the best target to improve functioning. However, a combined approach to intervention, targeting reductions in body fat percentage, pain and improvements in physical activity and CRF may assist physical functioning.

Association of a low density lipoprotein receptor microsatellite variant with obesity

OBJECTIVE: To determine whether a microsatellite polymorphism located towards the 3' end of the low density lipoprotein receptor gene (LDLR) is associated with obesity. DESIGN: A cross-sectional case-control study. SUBJECTS: One hundred and seven obese individuals, defined as a body mass index (BMI) > or = 26 kg/m2, and 163 lean individuals, defined as a BMI < 26 kg/m2. MEASUREMENTS: BMI, blood pressure, serum lipids, alleles of LDLR microsatellite (106 bp, 108 bp and 112 bp). RESULTS: There was a significant association between variants of the LDLR microsatellite and obesity, in the overall tested population, due to a contributing effect in females (chi 2 = 12.3, P = 0.002), but not in males (chi 2 = 0.3, P = 0.87). In females, individuals with the 106 bp allele were more likely to be lean, while individuals with the 112 bp and/or 108 bp alleles tended to be obese. CONCLUSIONS: These results suggest that in females, LDLR may play a role in the development of obesity.

Physical activity, obesity status, and blood pressure in preschool children

Objective To examine the combined effects of physical activity and weight status on blood pressure (BP) in preschool-aged children. Study design The sample included 733 preschool-aged children (49% female). Physical activity was objectively assessed on 7 consecutive days by accelerometry. Children were categorized as sufficiently active if they met the recommendation of at least 60 minutes daily of moderate-to-vigorous physical activity (MVPA). Body mass index was used to categorize children as nonoverweight or overweight/obese, according to the International Obesity Task Force benchmarks. BP was measured using an automated BP monitor and categorized as elevated or normal using BP percentile-based cut-points for age, sex, and height. Results The prevalence of elevated systolic BP (SBP) and diastolic BP was 7.7% and 3.0%, respectively. The prevalence of overweight/obese was 32%, and about 15% of children did not accomplish the recommended 60 minutes of daily MVPA. After controlling for age and sex, overweight/obese children who did not meet the daily MVPA recommendation were 3 times more likely (OR 3.8; CI 1.6-8.6) to have elevated SBP than nonoverweight children who met the daily MVPA recommendation. Conclusions Overweight or obese preschool-aged children with insufficient levels of MVPA are at significantly greater risk for elevated SBP than their nonoverweight and sufficiently active counterparts.

The clinical effectiveness and cost-effectiveness of exercise referral schemes: A systematic review and economic evaluation

- Background Exercise referral schemes (ERS) aim to identify inactive adults in the primary-care setting. The GP or health-care professional then refers the patient to a third-party service, with this service taking responsibility for prescribing and monitoring an exercise programme tailored to the needs of the individual. - Objective To assess the clinical effectiveness and cost-effectiveness of ERS for people with a diagnosed medical condition known to benefit from physical activity (PA). The scope of this report was broadened to consider individuals without a diagnosed condition who are sedentary. - Data sources MEDLINE; EMBASE; PsycINFO; The Cochrane Library, ISI Web of Science; SPORTDiscus and ongoing trial registries were searched (from 1990 to October 2009) and included study references were checked. - Methods Systematic reviews: the effectiveness of ERS, predictors of ERS uptake and adherence, and the cost-effectiveness of ERS; and the development of a decision-analytic economic model to assess cost-effectiveness of ERS. - Results Seven randomised controlled trials (UK, n = 5; non-UK, n = 2) met the effectiveness inclusion criteria, five comparing ERS with usual care, two compared ERS with an alternative PA intervention, and one to an ERS plus a self-determination theory (SDT) intervention. In intention-to-treat analysis, compared with usual care, there was weak evidence of an increase in the number of ERS participants who achieved a self-reported 90-150 minutes of at least moderate-intensity PA per week at 6-12 months' follow-up [pooled relative risk (RR) 1.11, 95% confidence interval 0.99 to 1.25]. There was no consistent evidence of a difference between ERS and usual care in the duration of moderate/vigorous intensity and total PA or other outcomes, for example physical fitness, serum lipids, health-related quality of life (HRQoL). There was no between-group difference in outcomes between ERS and alternative PA interventions or ERS plus a SDT intervention. None of the included trials separately reported outcomes in individuals with medical diagnoses. Fourteen observational studies and five randomised controlled trials provided a numerical assessment of ERS uptake and adherence (UK, n = 16; non-UK, n = 3). Women and older people were more likely to take up ERS but women, when compared with men, were less likely to adhere. The four previous economic evaluations identified suggest ERS to be a cost-effective intervention. Indicative incremental cost per quality-adjusted life-year (QALY) estimates for ERS for various scenarios were based on a de novo model-based economic evaluation. Compared with usual care, the mean incremental cost for ERS was £169 and the mean incremental QALY was 0.008, with the base-case incremental cost-effectiveness ratio at £20,876 per QALY in sedentary people without a medical condition and a cost per QALY of £14,618 in sedentary obese individuals, £12,834 in sedentary hypertensive patients, and £8414 for sedentary individuals with depression. Estimates of cost-effectiveness were highly sensitive to plausible variations in the RR for change in PA and cost of ERS. - Limitations We found very limited evidence of the effectiveness of ERS. The estimates of the cost-effectiveness of ERS are based on a simple analytical framework. The economic evaluation reports small differences in costs and effects, and findings highlight the wide range of uncertainty associated with the estimates of effectiveness and the impact of effectiveness on HRQoL. No data were identified as part of the effectiveness review to allow for adjustment of the effect of ERS in different populations. - Conclusions There remains considerable uncertainty as to the effectiveness of ERS for increasing activity, fitness or health indicators or whether they are an efficient use of resources in sedentary people without a medical diagnosis. We failed to identify any trial-based evidence of the effectiveness of ERS in those with a medical diagnosis. Future work should include randomised controlled trials assessing the cinical effectiveness and cost-effectivenesss of ERS in disease groups that may benefit from PA. - Funding The National Institute for Health Research Health Technology Assessment programme.

The cost-effectiveness of exercise referral schemes

Background Exercise referral schemes (ERS) aim to identify inactive adults in the primary care setting. The primary care professional refers the patient to a third party service, with this service taking responsibility for prescribing and monitoring an exercise programme tailored to the needs of the patient. This paper examines the cost-effectiveness of ERS in promoting physical activity compared with usual care in primary care setting. Methods A decision analytic model was developed to estimate the cost-effectiveness of ERS from a UK NHS perspective. The costs and outcomes of ERS were modelled over the patient's lifetime. Data were derived from a systematic review of the literature on the clinical and cost-effectiveness of ERS, and on parameter inputs in the modelling framework. Outcomes were expressed as incremental cost per quality-adjusted life-year (QALY). Deterministic and probabilistic sensitivity analyses investigated the impact of varying ERS cost and effectiveness assumptions. Sub-group analyses explored the cost-effectiveness of ERS in sedentary people with an underlying condition. Results Compared with usual care, the mean incremental lifetime cost per patient for ERS was £169 and the mean incremental QALY was 0.008, generating a base-case incremental cost-effectiveness ratio (ICER) for ERS at £20,876 per QALY in sedentary individuals without a diagnosed medical condition. There was a 51% probability that ERS was cost-effective at £20,000 per QALY and 88% probability that ERS was cost-effective at £30,000 per QALY. In sub-group analyses, cost per QALY for ERS in sedentary obese individuals was £14,618, and in sedentary hypertensives and sedentary individuals with depression the estimated cost per QALY was £12,834 and £8,414 respectively. Incremental lifetime costs and benefits associated with ERS were small, reflecting the preventative public health context of the intervention, with this resulting in estimates of cost-effectiveness that are sensitive to variations in the relative risk of becoming physically active and cost of ERS. Conclusions ERS is associated with modest increase in lifetime costs and benefits. The cost-effectiveness of ERS is highly sensitive to small changes in the effectiveness and cost of ERS and is subject to some significant uncertainty mainly due to limitations in the clinical effectiveness evidence base.

Exercise and vascular function in child obesity: A meta-analysis

CONTEXT: Conduit artery flow-mediated dilation (FMD) is a noninvasive index of preclinical atherosclerosis in humans. Exercise interventions can improve FMD in both healthy and clinical populations. OBJECTIVE: This systematic review and meta-analysis aimed to summarize the effect of exercise training on FMD in overweight and obese children and adolescents as well as investigate the role of cardiorespiratory fitness (peak oxygen consumption [Vo2peak]) on effects observed. DATA SOURCES: PubMed, Medline, Embase, and Cinahl databases were searched from the earliest available date to February 2015. STUDY SELECTION: Studies of children and/or adolescents who were overweight or obese were included. DATA EXTRACTION: Standardized data extraction forms were used for patient and intervention characteristics, control/comparator groups, and key outcomes. Procedural quality of the studies was assessed using a modified version of the Physiotherapy Evidence Base Database scale. RESULTS: A meta-analysis involving 219 participants compared the mean difference of pre- versus postintervention vascular function (FMD) and Vo2peak between an exercise training intervention and a control condition. There was a significantly greater improvement in FMD (mean difference 1.54%, P < .05) and Vo2peak (mean difference 3.64 mL/kg/min, P < .05) after exercise training compared with controls. LIMITATIONS: Given the diversity of exercise prescriptions, participant characteristics, and FMD measurement protocols, varying FMD effect size was noted between trials. CONCLUSIONS: Exercise training improves vascular function in overweight and obese children, as indicated by enhanced FMD. Further research is required to establish the optimum exercise program for maintenance of healthy vascular function in this at-risk pediatric population.

Maternal perception of weight status in first-born Australian toddlers aged 12–16 months – the NOURISH and SAIDI cohorts

Background The preference amongst parents for heavier infants is in contrast to obesity prevention efforts worldwide. Parents are poor at identifying overweight in older children, but few studies have investigated maternal perception of weight status amongst toddlers and none in the Australian setting. Methods Mothers (n = 290) completed a self-administered questionnaire at child age 12–16 months, defining their child's weight status as underweight, normal weight, somewhat overweight or very overweight. Weight-for-length z-score was derived from measured weight and length, and children categorized as underweight, normal weight, at risk overweight or obese (WHO standards). Objective classification was compared with maternal perception of weight status. Mean weight-for-length z-score was compared across categories of maternal perception using one-way ANOVA. Multinomial logistic regression was used to determine child or maternal characteristics associated with inaccurate weight perception. Results Most children (83%) were perceived as normal weight. Twenty nine were described as underweight, although none were. Sixty-six children were at risk of overweight, but 57 of these perceived as normal weight. Of the 14 children who were overweight, only 4 were identified as somewhat overweight by their mother. Compared with mothers who could accurately classify their normal weight child, mothers who were older had higher odds of perceiving their normal weight child as underweight, while mothers with higher body mass index had slightly higher odds of describing their overweight/at risk child as normal weight. Conclusion The leaner but healthy weight toddler was perceived as underweight, while only the heaviest children were recognized as overweight. Mothers unable to accurately identify children at risk are unlikely to act to prevent further excess weight gain. Practitioners can lead a shift in attitudes towards weight in infants and young children, promoting routine growth monitoring and adequate but not rapid weight gain.

Morbid obesity in total hip arthroplasty: Redefining outcomes for operative time, length of stay, and readmission

Background The incidence of obesity amongst patients presenting for elective Total Hip Arthroplasty (THA) has increased in the last decade and the relationship between obesity and the need for joint replacement has been demonstrated. This study evaluates the effects of morbid obesity on outcomes following primary THA by comparing short-term outcomes in THA between a morbidly obese (BMI ≥40) and a normal weight (BMI 18.5 - <25) cohort at our institution between January 2003 and December 2010. Methods Thirty-nine patients included in the morbidly obese group were compared with 186 in the normal weight group. Operative time, length of stay, complications, readmission and length of readmission were compared. Results Operative time was increased in the morbidly obese group at 122 minutes compared with 100 minutes (p=0.002). Post-operatively there was an increased 30-day readmission rate related to surgery of 12.8% associated with BMI ≥40 compared with 2.7% (p= 0.005) as well as a 5.1 fold increase in surgery related readmitted bed days - 0.32 bed days per patient for normal weight compared with 1.64 per patient for the morbidly obese (p=0.026). Conclusion Morbidly obese patients present a technical challenge and likely this and the resultant complications are underestimated. More work needs to be performed in order to enable suitable allocation of resources.