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ABSTRACT: Objective:We investigated to what extent changes in metabolic rate and composition of weight loss explained the less-than-expected weight loss in obese men and women during a diet-plus-exercise intervention.Design:In all, 16 obese men and women (41±9 years; body mass index (BMI) 39±6 kg m(-2)) were investigated in energy balance before, after and twice during a 12-week very-low-energy diet(565-650 kcal per day) plus exercise (aerobic plus resistance training) intervention. The relative energy deficit (EDef) from baseline requirements was severe (74%-87%). Body composition was measured by deuterium dilution and dual energy X-ray absorptiometry, and resting metabolic rate (RMR) was measured by indirect calorimetry. Fat mass (FM) and fat-free mass (FFM) were converted into energy equivalents using constants 9.45 kcal per g FM and 1.13 kcal per g FFM. Predicted weight loss was calculated from the EDef using the '7700 kcal kg(-1) rule'.Results:Changes in weight (-18.6±5.0 kg), FM (-15.5±4.3 kg) and FFM (-3.1±1.9 kg) did not differ between genders. Measured weight loss was on average 67% of the predicted value, but ranged from 39% to 94%. Relative EDef was correlated with the decrease in RMR (R=0.70, P<0.01), and the decrease in RMR correlated with the difference between actual and expected weight loss (R=0.51, P<0.01). Changes in metabolic rate explained on average 67% of the less-than-expected weight loss, and variability in the proportion of weight lost as FM accounted for a further 5%. On average, after adjustment for changes in metabolic rate and body composition of weight lost, actual weight loss reached 90% of the predicted values.Conclusion:Although weight loss was 33% lower than predicted at baseline from standard energy equivalents, the majority of this differential was explained by physiological variables. Although lower-than-expected weight loss is often attributed to incomplete adherence to prescribed interventions, the influence of baseline calculation errors and metabolic downregulation should not be discounted.International Journal of Obesity advance online publication, 24 July 2012; doi:10.1038/ijo.2012.109.
International journal of obesity (2005) 07/2012; · 4.34 Impact Factor
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ABSTRACT: To develop and cross-validate bioelectrical impedance analysis (BIA) prediction equations of total body water (TBW) and fat-free mass (FFM) for Asian pre-pubertal children from China, Lebanon, Malaysia, Philippines and Thailand.
Height, weight, age, gender, resistance and reactance measured by BIA were collected from 948 Asian children (492 boys and 456 girls) aged 8-10 years from the five countries. The deuterium dilution technique was used as the criterion method for the estimation of TBW and FFM. The BIA equations were developed using stepwise multiple regression analysis and cross-validated using the Bland-Altman approach.
The BIA prediction equation for the estimation of TBW was as follows: TBW=0.231 × height(2)/resistance+0.066 × height+0.188 × weight+0.128 × age+0.500 × sex-0.316 × Thais-4.574 (R (2)=88.0%, root mean square error (RMSE)=1.3 kg), and for the estimation of FFM was as follows: FFM=0.299 × height(2)/resistance+0.086 × height+0.245 × weight+0.260 × age+0.901 × sex-0.415 × ethnicity (Thai ethnicity =1, others = 0)-6.952 (R (2)=88.3%, RMSE=1.7 kg). No significant difference between measured and predicted values for the whole cross-validation sample was found. However, the prediction equation for estimation of TBW/FFM tended to overestimate TBW/FFM at lower levels whereas underestimate at higher levels of TBW/FFM. Accuracy of the general equation for TBW and FFM was also valid at each body mass index category.
Ethnicity influences the relationship between BIA and body composition in Asian pre-pubertal children. The newly developed BIA prediction equations are valid for use in Asian pre-pubertal children.
European journal of clinical nutrition 07/2011; 65(12):1321-7. · 3.07 Impact Factor
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ABSTRACT: 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.
Obesity Reviews 07/2011; 12(11):935-51. · 7.04 Impact Factor
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N A King,
K Horner,
A P Hills, N M Byrne,
R E Wood,
E Bryant,
P Caudwell,
G Finlayson,
C Gibbons,
M Hopkins,
C Martins,
J E Blundell
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ABSTRACT: Does exercise promote weight loss? One of the key problems with studies assessing the efficacy of exercise as a method of weight management and obesity is that mean data are presented and the individual variability in response is overlooked. Recent data have highlighted the need to demonstrate and characterise the individual variability in response to exercise. Do people who exercise compensate for the increase in energy expenditure via compensatory increases in hunger and food intake? The authors address the physiological, psychological and behavioural factors potentially involved in the relationship between exercise and appetite, and identify the research questions that remain unanswered. A negative consequence of the phenomena of individual variability and compensatory responses has been the focus on those who lose little weight in response to exercise; this has been used unreasonably as evidence to suggest that exercise is a futile method of controlling weight and managing obesity. Most of the evidence suggests that exercise is useful for improving body composition and health. For example, when exercise-induced mean weight loss is <1.0 kg, significant improvements in aerobic capacity (+6.3 ml/kg/min), systolic (-6.00 mm Hg) and diastolic (-3.9 mm Hg) blood pressure, waist circumference (-3.7 cm) and positive mood still occur. However, people will vary in their responses to exercise; understanding and characterising this variability will help tailor weight loss strategies to suit individuals.
British journal of sports medicine 05/2011; 46(5):315-22. · 2.55 Impact Factor
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ABSTRACT: 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.
Obesity Reviews 12/2009; 11(10):740-9. · 7.04 Impact Factor
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ABSTRACT: Obesity associated with atypical antipsychotic medications is an important clinical issue for people with schizophrenia. The purpose of this project was to determine whether there were any differences in resting energy expenditure (REE) and respiratory quotient (RQ) between men with schizophrenia and controls.
Thirty-one men with schizophrenia were individually matched for age and relative body weight with healthy, sedentary controls. Deuterium dilution was used to determine total body water and subsequently fat-free mass (FFM). Indirect calorimetry using a Deltatrac metabolic cart was used to determine REE and RQ.
When corrected for FFM, there was no significant difference in REE between the groups. However, fasting RQ was significantly higher in the men with schizophrenia than the controls.
Men with schizophrenia oxidised proportionally less fat and more carbohydrate under resting conditions than healthy controls. These differences in substrate utilisation at rest may be an important consideration in obesity in this clinical group.
Acta Psychiatrica Scandinavica 02/2009; 119(6):451-6. · 4.22 Impact Factor
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ABSTRACT: To measure adherence to a specific exercise prescription (1500 kcal week(-1)) by objectively quantifying unsupervised exercise energy expenditure (ExEE) in obese women.
The 16-week lifestyle intervention consisted of weekly meetings with research staff and promotion of increased ExEE (1500 kcal week(-1)) and a decreased dietary intake (-500 kcal day(-1)).
Twenty-nine obese females (body mass index=36.8+/-5.0 kg m(-2), body fat=49.6+/-3.7%) from a hospital-based lifestyle intervention were included in the analysis.
ExEE was estimated and monitored weekly using heart rate monitoring, and body composition was measured before and after the intervention by dual-energy X-ray absorptiometry.
Free-living adherence to the exercise prescription was variable and, on average, modest such that 14% achieved 1500 kcal week(-1), and the average weekly ExEE (768 kcal week(-1)) represented 51.2% of the total amount prescribed. ExEE was correlated with changes in body weight (r=0.65, P<0.001) and fat mass (r=0.65, P<0.001). Achievement of a 5% weight loss target was dependent on the achievement of an ExEE level of 1000 kcal week(-1) (P<0.001). Exercise 'adherers' (>1000 kcal week(-1)) lost more weight (-9.9 vs -4.1 kg), more fat mass (-6.8 vs -3.0 kg) and more waist circumference (-9.8 vs -5.6 cm) when compared to 'non-adherers' (<1000 kcal week(-1)).
Exercise is an integral component of lifestyle interventions aimed at reducing obesity and its complications. However, without accurate and objective measures of ExEE, it is difficult for relationships between exercise and health outcomes to be elucidated. The present study suggests an alternative to self-report to increase the confidence with which conclusions are drawn regarding the role of exercise within lifestyle interventions.
International journal of obesity (2005) 06/2008; 32(5):837-44. · 4.34 Impact Factor
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ABSTRACT: To determine the minimum number of days of dietary intake interviews required to reduce the effects of random error (day-to-day variability in dietary intake) when using the multiple-pass, multiple-day, 24-h recall method.
Cross-sectional study.
University research department.
A total of 50 healthy non-smoking overweight and obese (body mass index=26-40 kg/m2) adult men and women aged 39-45 years completed the study. Participants were randomly selected from volunteers for a larger unrelated study.
Each participant completed 10, multiple-pass, 24-h recall interviews on randomly chosen days over 4 weeks. The minimum number of record days was determined for each macronutrient (carbohydrate, fat, protein) and energy, for each gender, to obtain a 'true' (unobservable) representative intake from reported (observed) dietary intakes.
The greatest number of days required to obtain a 'true' representative intake was 8 days. Carbohydrate intakes required the greatest number of days of dietary record among males (7 days), whereas protein required the greatest number of days among females (8 days) in this cohort. Sunday was the day of the week that showed greatest variability in macronutrient intakes. Protein (P<0.05) and fat (P<0.001) intakes were significantly more variable than carbohydrate on Sundays compared with weekdays, for both men and women.
A logistically achievable 8 days of dietary intake interviews was sufficient to minimize the effect of random error when using the multiple-pass, 24-h recall dietary intake method. Sunday should be included among the dietary interview days to ensure a 'true' representation of macronutrient intakes. This method can be confidently applied to small cohort studies in which dietary intakes from different groups are to be compared or to investigations of associations between nutrient intakes and disease.
European Journal of Clinical Nutrition 05/2008; 62(4):537-43. · 2.46 Impact Factor
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ABSTRACT: To investigate the variability in isotopic equilibrium time under field conditions, and the impact of this variability on estimates of total body water (TBW) and body composition.
Following collection of a fasting baseline urine sample, 10 women and 10 men were dosed with deuterium oxide (0.05 g/kg body weight). Urine samples were collected every hour for 8 h. The samples were analysed using isotope ratio mass spectrometry. Time to equilibration was determined using three commonly employed data analysis approaches.
Isotopic equilibrium was reached by 50, 80 and 100% of participants at 4, 6 and 8 h, respectively. The mean group equilibration determined using the three different plateau determination methods were 4.8+/-1.5, 3.8+/-0.8 and 4.9+/-1.4 h. Isotopic enrichment, TBW, and percent body fat estimates differed between early (3-5 h), but not later sampling times (5-8 h).
Although the three different plateau determination approaches resulted in differences in equilibration time, all suggest that sampling at 6 h or later will decrease the likelihood of error in body composition estimates resultant from incomplete isotopic equilibration in a small proportion of individuals.
European Journal of Clinical Nutrition 12/2007; 61(11):1250-5. · 2.46 Impact Factor
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ABSTRACT: Despite the multifactorial nature of musculoskeletal disease, obesity consistently emerges as a key and potentially modifiable risk factor in the onset and progression of musculoskeletal conditions of the hip, knee, ankle, foot and shoulder. To date, the majority of research has focused on the impact of obesity on bone and joint disorders, such as the risk of fracture and osteoarthritis. However, emerging evidence indicates that obesity may also have a profound effect on soft-tissue structures, such as tendon, fascia and cartilage. Although the mechanism remains unclear, the functional and structural limitations imposed by the additional loading of the locomotor system in obesity have been almost universally accepted to produce aberrant mechanics during locomotor tasks, thereby unduly raising stress within connective-tissue structures and the potential for musculoskeletal injury. While such mechanical theories abound, there is surprisingly little scientific evidence directly linking musculoskeletal injury to altered biomechanics in the obese. For the most part, even the biomechanical effects of obesity on the locomotor system remain unknown. Given the global increase in obesity and the rapid rise in musculoskeletal disorders, there is a need to determine the physical consequences of continued repetitive loading of major structures of the locomotor system in the obese and to establish how obesity may interact with other factors to potentially increase the risk of musculoskeletal disease.
Obesity Reviews 09/2006; 7(3):239-50. · 7.04 Impact Factor
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ABSTRACT: Despite the greater prevalence of musculoskeletal disorders in obese adults, the consequences of childhood obesity on the development and function of the musculoskeletal system have received comparatively little attention within the literature. Of the limited number of studies performed to date, the majority have focused on the impact of childhood obesity on skeletal structure and alignment, and to a lesser extent its influence on clinical tests of motor performance including muscular strength, balance and locomotion. Although collectively these studies imply that the functional and structural limitations imposed by obesity may result in aberrant lower limb mechanics and the potential for musculoskeletal injury, empirical verification is currently lacking. The delineation of the effects of childhood obesity on musculoskeletal structure in terms of mass, adiposity, anthropometry, metabolic effects and physical inactivity, or their combination, has not been established. More specifically, there is a lack of research regarding the effect of childhood obesity on the properties of connective tissue structures, such as tendons and ligaments. Given the global increase in childhood obesity, there is a need to ascertain the consequences of persistent obesity on musculoskeletal structure and function. A better understanding of the implications of childhood obesity on the development and function of the musculoskeletal system would assist in the provision of more meaningful support in the prevention, treatment and management of the musculoskeletal consequences of the condition.
Obesity Reviews 06/2006; 7(2):209-18. · 7.04 Impact Factor
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ABSTRACT: In spite of significant advances in the knowledge and understanding of the multi-factorial nature of obesity, many questions regarding the specific consequences of the disease remain unanswered. In particular, there is a relative dearth of information pertaining to the functional limitations imposed by overweight and obesity. The limited number of studies to date have mainly focused on the effect of obesity on the temporospatial characteristics of walking, plantar foot pressures, muscular strength and, to a lesser extent, postural balance. Collectively, these studies have implied that the functional limitations imposed by the additional loading of the locomotor system in obesity result in aberrant mechanics and the potential for musculoskeletal injury. Despite the greater prevalence of musculoskeletal disorders in the obese, there has been surprisingly little empirical investigation pertaining to the biomechanics of activities of daily living or into the mechanical and neuromuscular factors that may predispose the obese to injury. A better appreciation of the implications of increased levels of body adiposity on the movement capabilities of the obese would afford a greater opportunity to provide meaningful support in preventing, treating and managing the condition and its sequelae. Moreover, there is an urgent need to establish the physical consequences of continued repetitive loading of major structures of the body, particularly of the lower limbs in the obese, during the diverse range of activities of daily living.
Obesity Reviews 03/2006; 7(1):13-24. · 7.04 Impact Factor
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ABSTRACT: Obesity is a significant health problem and the incidence of the condition is increasing at an alarming rate worldwide. Despite significant advances in the knowledge and understanding of the multifactorial nature of the condition, many questions regarding the specific consequences of the disease remain unanswered. For example, there is a dearth of information pertaining to the structural and functional limitations imposed by overweight and obesity. A limited number of studies to date have considered plantar pressures under the feet of obese vs. non-obese, the influence of foot structure on performance, gait characteristics of obese children and adults, and relationships between obesity and osteoarthritis. A better appreciation of the implications of increased levels of body weight and/or body fat on movement capabilities of the obese would provide an enhanced opportunity to offer more meaningful support in the prevention, treatment and management of the condition.
Obesity Reviews 03/2002; 3(1):35-43. · 7.04 Impact Factor
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ABSTRACT: Obesity is a significant health problem and the incidence of the condition is increasing at an alarming rate worldwide. Despite significant advances in the knowledge and understanding of the multifactorial nature of the condition, many questions regarding the specific consequences of the disease remain unanswered. For example, there is a dearth of information pertaining to the structural and functional limitations imposed by overweight and obesity. A limited number of studies to date have considered plantar pressures under the feet of obese vs. non-obese, the influence of foot structure on performance, gait characteristics of obese children and adults, and relationships between obesity and osteoarthritis. A better appreciation of the implications of increased levels of body weight and/or body fat on movement capabilities of the obese would provide an enhanced opportunity to offer more meaningful support in the prevention, treatment and management of the condition.
Obesity Reviews 01/2002; 3(1):35 - 43. · 7.04 Impact Factor
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ABSTRACT: The debate surrounding the level of intensity of exercise that is best for health improvement has potentially clouded the issue of optimal exercise prescription for weight management. Low-intensity activity is potentially superior to moderate to high intensity for improving metabolic risk factors, and accumulated small bouts of physical activity are as effective to this end as single longer bouts, as long as the overall volume of energy expenditure is equivalent. What should not be forgotten however, is that for weight-loss it is the total volume of energy expended that will dictate the size of the energy deficit imposed, not the composition of the exercise per se. Exercise prescription for weight management is a conundrum. Whilst it is the total volume of energy expended that will dictate the magnitude of weight lost, not the composition of the exercise per se, it is the nature of the exercise prescription that will dictate the long-term success of an exercise programme. It is how well the exercise prescription is individualized that influences tolerance of and interest in the programme and, thus, the adherence to it in the long term.
Proceedings of The Nutrition Society 02/1998; 57(1):93-103. · 2.77 Impact Factor
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ABSTRACT: Numerous approaches have been used to improve the science and art of exercise prescription, and particular challenges exist in the prescription of exercise intensity. Traditionally, work in the area has been the province of exercise physiologists interested in the improvement of training programmes for athletes, as opposed to the more widespread recent interest in health-related fitness and physical activity for all. The generalized approach to the provision of guidelines for exercise prescription has meant that individuals have, at best, prediction equations which provide a wide band of heart rate between which they can work to derive health benefits. This paper explores some of the commonly employed submaximal markers of exercise intensity and proposes a number of approaches for improvements beyond generalized equations.
Journal of Sports Sciences 01/1998; 16 Suppl:S71-6. · 1.93 Impact Factor
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Perceptual and Motor Skills 07/1997; 84(3 Pt 2):1330. · 0.49 Impact Factor
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ABSTRACT: For many people, there is a discrepancy between perceived and desired physical appearance. Attempts have been made to quantify this discrepancy as a measure of body-image disturbance: however, the use of measurement scales which are not population-specific may bias the assessment. To investigate whether ratings of body-images were affected by the scale employed, 57 male and 40 female adolescents were tested using both adult and adolescent body-figure silhouette scales. Significant between-scale differences were found, with adolescents displaying consistently lower body-image ratings when viewing adult as opposed to adolescent scales. In addition, between-sex differences in discrepancy scores and correlations between discrepancy scores and another measure of body satisfaction were significantly influenced by the scale employed. The results confirm the need for population-specific measurement scales and the implementation of standardised assessment procedures.
Perceptual and Motor Skills 07/1996; 82(3 Pt 1):747-53. · 0.49 Impact Factor
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ABSTRACT: The present study examined the association between socioeconomic status (SES), ethnicity, body dissatisfaction, and eating behaviours of 10- to 18-year-old children and adolescents. The study participants (N = 768) were categorised as Caucasian (74.7%), Chinese or Vietnamese (18.2%), and Italian or Greek (7.0%), and high (82%), middle (8.6%), and low SES (9.4%) according to parents' occupations. The chi squared, Mann-Whitney U test and Kruskal-Wallis test and logistic regression model were used to determine the interaction between variables. Females and older participants were more likely to desire a body figure that was thinner than their perceived current figure. Furthermore, the same groups were also more likely to be preoccupied with eating problems (females 7.1% vs. males 1.4%; for participants aged 15-18 years, 7.8% vs. participants aged 10-14 years, 3.9%). The body dissatisfaction gender difference was females 42.8% vs. males 11.8%, and participants aged 15-18 years 41.7% vs. those aged 10-14 years, 28.3%. Participants whose parents were managers/professionals were more likely to desire a body figure that was thinner than their perceived current figure than those from white-collar and blue-collar families. This was also the case for Caucasian Australians compared to those from Chinese or Vietnamese backgrounds. In conclusion, age and gender differences in body image and problems in eating behaviour were evident among children and adolescents. However, there was no significant SES and ethnic difference in the proportion of participants with eating problems and body dissatisfaction.
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