Differences in daily energy expenditure in lean and obese women: the role of posture allocation

Weight loss does not affect the sit-to-stand metabolic cost in adolescents with obesity

PURPOSE

There is considerable interest in simple and effective methods to reduce sitting time and increase energy expenditure, and standing breaks have emerged as a realisable approach in individuals with obesity. The aim of the present study was to determine the extent to which energy expenditure in standing differs from sitting, and whether this energetic and metabolic-related responses are modified following a weight loss program in adolescents with obesity.

METHODS

After body composition assessment (DXA), cardiorespiratory and metabolic variables were continuously recorded (indirect calorimetry) during 10 min while sitting and then during 5 min standing posture before (n = 21; T1) and at the end of a multidisciplinary intervention (n = 17; T2) in adolescents with obesity.

RESULTS

Before and after the intervention, energy expenditure and fat oxidation rates were significantly increased in standing compared with sitting. Weight loss did not change the relationship between sitting and standing energy expenditure. Sitting energy expenditure represented 1.0 and 1.1 Metabolic Equivalent of Task at T1 and T2, and increased to 1.1 and 1.2 during standing at T1 and T2, respectively. The percentage of change of android fat mass between T1 and T2 was positively associated with the percentage of change in energy expenditure from sitting to standing at T2.

CONCLUSION

The vast majority of the adolescents with obesity significantly increased their energy expenditure between sitting and standing, both before and after a weight loss intervention. However, the standing posture did not allow breaking the sedentary threshold. Abdominal fat mass is associated with energic profile.

Does diet and activity lead to difference in resting energy expenditure in obese women?

BACKGROUND

Obesity is considered as a risk factor for metabolic and chronic diseases. Reduction in resting energy expenditure (REE) may increase risk of obesity. Our study was carried out to investigate dietary, biochemical, anthropometric and body composition parameters and physical activity in obese women with normal and low resting energy expenditure.

METHODS

A total forty nine subjects (women, 30-50 years old) were enrolled and divided into three groups. Anthropometric, body composition parameters, resting energy expenditure, Fasting blood lipid profile, dietary intake and physical activity were measured.

RESULTS

Although, fat mass and fat-free mass were significantly increased in obese groups, there was no significant difference in body composition between two obese groups (p-value = 0.10, 0.27). Measured resting energy expenditure was significantly decreased in obese with low REE compare to other groups (p-value < 0.001). There was no significant difference in energy intake and macronutrients between groups. There was a significant difference in T3 between obese subjects with low REE compared to obese group with normal REE (p-value < 0.001). There was no significant difference in lipid profile between two obese groups. Also there was a significant difference in LDL, cholesterol and triacylglycerol between obese subjects with low REE compared to normal weight group. Moreover, there was a significant difference in cholesterol and triacylglycerol between obese subjects with normal REE compared to normal weight group. Our finding showed there was no significant difference in physical activity between three groups.

CONCLUSIONS

Dietary intake and physical activity may relate to metabolism and energy expenditure. It is interesting that in some obese people resting energy expenditure was much lower compared to other obese people; however, there was no significant difference in their body composition, age, sex, dietary intake, lipid profile and physical activity. Thus it should investigate the role of other factors involved in different REE in subjects with obesity.

The role of physical activity in the regulation of body weight: The overlooked contribution of light physical activity and sedentary behaviors

The role of physical activity (PA) in the regulation of body weight is still a major topic of debate. This may be because studies have essentially focused on the effects of moderate/vigorous PA (MVPA) on body weight while overlooking the other components of PA, namely, light-intensity PA (LPA, daily life activities) and sedentary behaviors (SB, too much sitting). In this review, we will (i) describe the history of changes in PA behaviors that occurred with modernization; (ii) review data from cross-sectional and longitudinal studies that examined the associations between PA, SB, and measures of obesity; (iii) review interventional studies that investigated the effects of changes in PA and SB on body weight and adiposity; and (iv) discuss experimental studies that addressed potential biological mechanisms underlying the effects of PA and SB on weight regulation. Overall recent findings support the importance of considering all components of PA to better understand the regulation of energy balance and suggest an important role for LPA and SB in addition to MVPA on body weight regulation. Longitudinal large-scale rigorous studies are needed to advance our knowledge of the role of PA/SB in combating the obesity epidemic.

Association between sitting/lying down, standing, walking time and number of steps per day with the hormonal profile and resting energy expenditure of women with obesity living in a low-income region

Reducing sedentary behaviour (SB) and increasing physical activity (PA) by sitting less and standing/walking more is advised to prevent chronic diseases. However, the mechanisms underlying this recommendation are not well established, especially in individuals with obesity living in low-income regions. The present study evaluated whether there are associations between PA indicators (PAI - standing time, walking time and the number of steps/d) and SB indicators (SBI - sitting/lying down time) with the hormonal profile and resting energy expenditure (REE) of adult women living in a low-income region. This is a cross-sectional study. We collected data on hormones (insulin resistance, leptin and thyroid axis), body composition (tetrapolar bioimpedance), REE (indirect calorimetry), and PAI and SBI (triaxial accelerometers, ActivPAL). Multivariable linear models adjusting for age and fat-free mass were performed. Fifty-eight women (mean age of 31 years and BMI of 33 kg/m²) were included. The mean sitting/lying down time and standing time were 16·08 and 5·52 h/d, respectively. Sitting/lying down time showed a direct association with free thyroxine (FT₄) (β = 0·56 ng/dl; 95 % CI = -1·10, -0·02). Standing time showed a direct association with FT₄ (β = 0·75 ng/dl; 95 % CI = 0·01; 1·48) and inverse association with free triiodothyronine (β = -2·83 pg/ml 95 % CI = -5·56, -0·10). There were no associations between PAI and SBI with the REE, insulin resistance, leptin and thyroid-stimulating hormone. Thus, decreased SB is associated with thyroid hormones levels but not with REE, insulin resistance or leptin in women with obesity living in low-income regions.

The relationship between total energy expenditure and physical activity level in women living in an impoverished Brazilian urban area

OBJECTIVE

This study aimed to describe how strong is the relationship between TEE and PAL in women living in an impoverished Brazilian urban area.

METHODS

Anthropometric, hormonal (insulin, TSH, FT₄ , and FT₃ ), body composition (deuterium), TEE (doubly labeled water) and PAL (metabolic equivalent task [MET]-7-day triaxial accelerometer, ActivPAL®) data were collected from 55 women (mean age: 31y, mean BMI: 27.4 kg/m² ). Adjusted-TEE models were calculated incorporating the residuals of anthropometric, hormonal, and body composition variables in the TEE, to assess the relation between MET and adjusted-TEE, through three different analyzes: linear regression, nonlinear regression and change-point regression.

RESULTS

Most participants (89.1%, n = 49) were classified as low-active. There was no association between crude TEE and MET.h/d (R²  = 0.05; p = 0.09). There was a positive, although weak, linear relationship between adjusted-TEE and MET.h/d (β = 2705.26 kcal; 95% CI: 436.25; 4974.27; adj-R²  = 0.08). A change point of this relationship was identified in the MET.h/d value of 1.53 (SD = 0.02; adj-R² = 0.13). The association between adjusted-TEE and MET.h/d before the change point (β = 5101.46 kcal; 95%CI: 978.84; 9224.08; adj-R²  = 0.11) was stronger than the association in the full linear model, nevertheless, it was still weak. This association stop existing when it is assessed in individuals after the change point (β = -6609.92 kcal; 95%CI: -16773.24; 3553.40; adj-R²  = 0.08).

CONCLUSIONS

These results suggest that the relationship between TEE and PAL is weak and it is not completely linear in women living in an impoverished Brazilian urban area.

Analysis of Resting Energy Consumption and Its Influencing Factors in Stroke Patients with Severe Neurological Diseases: A Retrospective Clinical Study

BACKGROUND

This study aimed to observe the changes of resting energy metabolism in patients with severe neurological diseases, and to explore the effects of tracheostomy status, stroke severity, and complications on resting energy expenditure (REE) and respiratory quotient (RQ).

METHODS

A retrospective study was conducted in 105 patients with neurological rehabilitation who were hospitalized in the Rehabilitation Department of the Affiliated Jiangning Hospital of Nanjing Medical University from August 2018 to October 2021. REE was measured by Italian Cosmed k4b2 indirectly, and white blood cell count and C-reactive protein (CRP) were collected.

RESULTS

Among the 105 patients, there were 18 cases of mild stroke, 45 cases of moderate stroke, and 42 cases of severe stroke. The difference between predicted REE and actual REE among different degrees of stroke patients was statistically significant (p < 0.05); there was no significant difference in RQ values among different degrees of stroke patients (p > 0.05). Hemoglobin, albumin, and body mass index were significantly and positively correlated with predicted REE and actual REE, while CRP was significantly negatively correlated with predicted REE and actual REE. There was no significant difference in predicted REE, actual REE, and RQ between renal insufficiency, type 2 diabetes mellitus, and chronic obstructive pulmonary disease (p > 0.05). The CRP level could affect the REE of stroke patients.

CONCLUSION

Metabolic vehicle assay has a certain clinical value in accurately evaluating the metabolic needs and feeding level of patients.

The centenary of the Harris-Benedict equations: How to assess energy requirements best? Recommendations from the ESPEN expert group

BACKGROUND & AIMS

The year 2019 marked the centenary of the publication of the Harris and Benedict equations for estimation of energy expenditure. In October 2019 a Scientific Symposium was organized by the European Society for Clinical Nutrition and Metabolism (ESPEN) in Vienna, Austria, to celebrate this historical landmark, looking at what is currently known about the estimation and measurement of energy expenditure.

METHODS

Current evidence was discussed during the symposium, including the scientific basis and clinical knowledge, and is summarized here to assist with the estimation and measurement of energy requirements that later translate into energy prescription.

RESULTS

In most clinical settings, the majority of predictive equations have low to moderate performance, with the best generally reaching an accuracy of no more than 70%, and often lead to large errors in estimating the true needs of patients. Generally speaking, the addition of body composition measurements did not add to the accuracy of predictive equations. Indirect calorimetry is the most reliable method to measure energy expenditure and guide energy prescription, but carries inherent limitations, greatly restricting its use in real life clinical practice.

CONCLUSIONS

While the limitations of predictive equations are clear, their use is still the mainstay in clinical practice. It is imperative to recognize specific patient populations for whom a specific equation should be preferred. When available, the use of indirect calorimetry is advised in a variety of clinical settings, aiming to avoid under-as well as overfeeding.

ACCELEROMETRY UNDERESTIMATES ENERGY EXPENDITURE IN CIRCUIT-BASED RESISTANCE TRAINING

ABSTRACT Introduction: Accelerometry is a very accurate method for determining energy expenditure (EE) in endurance training. However, further studies are needed to prove its accuracy in resistance training. Objective: To compare the EE obtained by accelerometry and indirect calorimetry in three different circuit resistance training circuits. Methods: Six overweight volunteers performed three sets in three resistance training circuits: machine circuit (MC), free-weight circuit (FWC) and resistance + aerobic circuit (RAC). EE was measured by indirect calorimetry using an Oxycon Mobile® and by the accelerometers SenseWear® Armband Pro2 and ActiTrainer®. Results: ActiTrainer® and SenseWear® underestimated EE in all circuits when compared to indirect calorimetry (p<0.05). The difference was greater in the FWC: 44.4% METs and 81.4% Kcal for ActiTrainer® and 32.3% METs and 24.9% Kcal for SenseWear® compared to indirect calorimetry. Conclusion: Both ActiTrainer® and SenseWear® underestimated EE when compared to indirect calorimetry in three different resistance training circuits. Level of evidence II; Diagnostic studies - Investigating a diagnostic test.

Barriers of physical activity of women post breast cancer treatment in rural Poland

Physical activity (PA) is an important element of healthy lifestyle, plays a major part in primary and secondary prevention of environmental illness. We examined the level of PA over a period of 7 days using Silva ex3 Connect pedometers in women after breast cancer treatment (BCT). Participants were selected from rural areas with restricted access to recreational and rehabilitative services. Women post BCT exhibited a low level of PA, though not deviating significantly from that of healthy women of the same age. There is a need to increase the level of PA among both: women after BCT and healthy women.

Frequent sit-to-stand transitions and several short standing periods measured by hip-worn accelerometer are associated with smaller waist circumference among adults

This cross-sectional study analysed the association of sedentary behaviour (SB) and standing with waist circumference. Finnish adults aged 30-75 years from a sub-sample of population-based Health 2011 Study used a hip-worn tri-axial accelerometer (Hookie AM20, Traxmeet, Ltd, Espoo, Finland) for seven days. Those 1405 participants (57% women) who used accelerometer at least four days, minimum of 10 hours/day, were included. SB and standing were analysed in 6s epochs using validated algorithm. Daily total time, daily number and accumulated time from bouts (30s-5min,30s-10min,30s-15min,30s 30min,>5min,>10min,>15min, >30min) as well as daily number of sit-to-stand transitions were determined. Waist circumference (cm) was measured in standardized way. Participants' mean age was 52 years (SD 12.2). Mean waist circumference was 97cm (SD 12.3) in men and 87cm (SD 12.7) in women. According to multivariable stepwise linear regression analysis, sit-to-stand transitions [standardised regression coefficient (β)= -0.14, 95%CI -0.20 to -0.09], standing bouts of 30s-5min (β= -0.21, 95%CI -0.26 to -0.15) and number of 30s-30min SB bouts (β=0.12, 95%CI 0.06 to 0.17) were most strongly associated with waist circumference. Besides assessing total SB time, future studies should assess also different bout lengths of SB and sit-to-stand transitions and standing times should be assessed separately.

The pathogenesis of obesity

Body fat mass increases when energy intake exceeds energy expenditure. In the long term, a positive energy balance will result in obesity. The worldwide prevalence of obesity has increased dramatically, posing a serious threat to human health. Therefore, insight in the pathogenesis of obesity is important to identify novel prevention and treatment strategies. This review describes the physiology of energy expenditure and energy intake in the context of body weight gain in humans. We focus on the components of energy expenditure and the regulation of energy intake. Finally, we describe rare monogenetic causes leading to an impairment in central regulation of food intake and obesity.

The association between resting metabolic rate and metabolic syndrome May Be mediated by adipokines in overweight and obese women

AIMS

Adipokines play a major role in developing metabolic syndrome (MetS), and it has been found that there is a significant relationship between MetS and resting metabolic rate (RMR) in obese people. The present study aimed to investigate the mediatory effect of adipokines on the RMR-MetS relationship.

METHODS

This cross-sectional study included 263 obese and overweight women, mean BMI 33.28 (4.93) kg/m, and mean age 39.02 (11.60) who were assessed for RMR using indirect calorimetry. Moreover, using the body composition analyzer the Body composition was measured. Also, Enzyme-linked Immunosorbent Assay (ELISA) test provided a quantitative measurement of biochemical parameters.

RESULTS

The results indicated that women in low RMR group had higher fat mass (P < 0.0001), FFM (P = 0.002), weight (P = 0.006), BMI (P < 0.0001), age (P = 0.01), and hs-CRP (P = 0.001). The results did not confirm any significant mediating roles for RBP4 (P = 0.051, β = -0.28) and Vaspin (P = 0.06, β = 0.32) in the RMR-MetS relationship. Additionally, after a binary regression test, Omentin-1 showed a significant mediating role (P = 0.25, β = 0.04) as an interrelated agent to RMR and MetS.

CONCLUSION

As this study shows, Omentin-1 was found to play a significant mediating role as a mediatory agent in relationship between RMR and MetS.

Accuracy and Validity of Resting Energy Expenditure Predictive Equations in Middle-Aged Adults

Indirect calorimetry (IC) is considered the reference method to determine the resting energy expenditure (REE), but its use in a clinical context is limited. Alternatively, there is a number of REE predictive equations to estimate the REE. However, it has been shown that the available REE predictive equations could either overestimate or underestimate the REE as measured by IC. Moreover, the role of the weight status in the accuracy and validity of the REE predictive equations requires further attention. Therefore, this study aimed to determine the accuracy and validity of REE predictive equations in normal-weight, overweight, and obese sedentary middle-aged adults. A total of 73 sedentary middle-aged adults (53% women, 40⁻65 years old) participated in the study. We measured REE by indirect calorimetry, strictly following the standard procedures, and we compared it with the values obtained from 33 predictive equations. The most accurate predictive equations in middle-aged sedentary adults were: (i) the equation of FAO/WHO/UNU in normal-weight individuals (50.0% of prediction accuracy), (ii) the equation of Livingston in overweight individuals (46.9% of prediction accuracy), and (iii) the equation of Owen in individuals with obesity (52.9% of prediction accuracy). Our study shows that the weight status plays an important role in the accuracy and validity of different REE predictive equations in middle-aged adults.

Comparison the time to stabilization and activity of the lower extremity muscles during jump-landing in subjects with and without Genu Varum

BACKGROUND

Knee muscles activity changes from Genu Varum deformity(GVD), may cause this individual more exposed to lower extremity injuries especially in high-risk activities like landing.

OBJECTIVE

The aim of this study was to compare the activity of the lower limb stabilizer muscles during jump-landing and time to stabilization(TTS) in subjects with and without GVD.

METHOD

A total of 44 men (group 1, with GVD n = 22 and group 2, without GVD n = 22); with mean age = 17.6 ± 3.12 years, height = 178.2 ± 5.39 cm, mass = 80.39 ± 8.3 kg) participated in this study. Subjects were asked to do a jump-landing task and Quadratus Lumborum(QL), Gluteus Maximus(GMax), Gluteus Medius(GMed), Biceps Femoris (BF), Semitendinosus, and Medial Gastrocnemius(MG) muscles activity was recorded. Also, changes in the amount of ground reaction force(GRF) were used to an indicator for TTS.

RESULTS

Our results showed that subjects with GVD had increased QL activity before(P = 0.008) and after(P = 0.017) landing. But, these subjects had a decreased activity of GMed compared to the healthy ones before(P = 0.033) and after(P = 0.005) landing. but there was no statistically significant difference before landing in gluteus maximus(P = 0.252), biceps femoris(P = 0.613), semitendinosus(P = 0.313), and medial gastrocnemius(P = 0.140) muscles and after landing in gluteus maximus (P = 0.246), biceps femoris(P = 0.512), semitendinosus(P = 0.214), and medial gastrocnemius(P = 0.209) muscles between the two groups. Also, the TTS was higher in subjects with GV than healthy ones in the Resultant Vector TTS (P = 0.015) and medial-lateral(P = 0.013) directions.

CONCLUSIONS

The altered activity of the QL and GMed, in subjects with GVD may indicate instability of the spinal column, pelvis and hip during jump-landing task. Although the GVD is referred to the frontal plane deformity, the results showed that this complication might affect stability in other motion planes.

Non-exercise activity thermogenesis (NEAT): a component of total daily energy expenditure

[Purpose]

The purpose of this review is to promote awareness of non-exercise activity thermogenesis (NEAT) as a new strategy to increase energy expenditure, and to manage obesity.

[Methods]

The content of this review is based on a literature search of PubMed and the Google Scholar search engine, using the search terms obesity, energy expenditure, non-exercise activity thermogenesis (NEAT), and sitting disease.

[Results]

Daily energy expenditure is of great interest because most obese individuals have no exercise activity-related thermogenesis (EAT); thus their physical activity-related energy expenditure (PEE) is comprised almost entirely of NEAT. Consequently, NEAT represents the main variable component of daily total energy expenditure (TEE); this varies considerably, both within among individuals. These somewhat unplanned and unstructured low level physical activities are associated with energy expenditure in excess of the resting metabolic rate (RMR). They may therefore have the potential to stimulate greater energy expenditure over time with a higher rate of adherence.

[Conclusion]

In conclusion, NEAT is a highly variable component of daily TEE and a low level of NEAT is associated with obesity. NEAT enhances lifestyle, and variations in individual and environmental factors can significantly affect daily energy expenditure. Therefore, well designed longitudinal studies that focus on personal behavioral approaches and re-engineered environments to increase NEAT should be conducted in the future.

Posture Allocation Revisited: Breaking the Sedentary Threshold of Energy Expenditure for Obesity Management

There is increasing recognition that low-intensity physical activities of daily life play an important role in achieving energy balance and that their societal erosion through substitution with sedentary (mostly sitting) behaviors, whether occupational or for leisure, impact importantly on the obesity epidemic. This has generated considerable interest for better monitoring, characterizing, and promoting countermeasures to sedentariness through a plethora of low-level physical activities (e.g., active workstations, standing desks, sitting breaks), amid the contention that altering posture allocation (lying, sitting, standing) can modify energy expenditure to impact upon body weight regulation and health. In addressing this contention, this paper first revisits the past and more recent literature on postural energetics, with particular emphasis on potential determinants of the large inter-individual variability in the energy cost of standing and the impact of posture on fat oxidation. It subsequently analyses the available data pertaining to various strategies by which posture allocations, coupled with light physical activity, may increase energy expenditure beyond the sedentary threshold, and their relevance as potential targets for obesity management.

Adipokines may mediate the relationship between resting metabolic rates and bone mineral densities in obese women

The researchers sought to test the possible link between resting metabolic rate and bone mineral density through four adipokines. Participants with lower resting metabolic rate (RMR) per kilogram demonstrated higher total bone mineral density (BMD), total T-score, and total Z-score. Omentin-1 had a mediatory effect on the relationship between RMR/kg of body weight and bone parameters.

INTRODUCTION

The previous results of studies regarding the links between obesity and bone health are controversial. For this reason, the researchers sought to test the possible link between RMR and BMD through the following four adipokines: vaspin, retinol binding protein 4, angiopoietin-like 6 (ANGPL6), and omentin-1.

METHODS

We enrolled 312 obese Iranian women (30 ≤ body mass index <40) in this cross-sectional study. In order to examine the association of serum adipokine levels with RMR and BMD, the participants were grouped based on RMR per body weight. Body composition, dietary intake, bone mineral density, and resting metabolic rate were assessed in all participants. Serum adipokine levels were quantified by the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

Low levels of RMR/kg were strongly associated with higher weight, body mass index, fat mass, and visceral fat levels. In fact, participants with an RMR/kg of body weight <20 kcal/24 h/kg were more obese (p < 0.05). Another noteworthy finding was that participants with lower RMR/kg demonstrated higher total BMD, total T-score, and total Z-score. Our results showed that omentin-1 had a mediatory effect on the relationship between RMR per kilogram of body weight and bone parameters (p < 0.05). Nevertheless, other adipokines such as vaspin, retinol-binding protein 4 (RBP4), and ANGPL6 did not affect the relationship between RMR and BMD (p > 0.05).

CONCLUSIONS

The inhibitory effect of omentin-1 on TNF-alpha seems to be able to reduce the amount of circulating leptin as adipokine, affecting energy expenditure and improving bone loss induced by estrogen deficiency and controlled effect of RMR on BMD.

Physical Activity, Energy Expenditure, and Defense of Body Weight in Melanocortin 4 Receptor-Deficient Male Rats

Melanocortin 4 receptor (MC4R) variants contribute to human obesity, and rats lacking functional MC4R (Mc4r^K314X/K314X) are obese. We investigated the hypothesis that low energy expenditure (EE) and physical activity contribute to this obese phenotype in male rats, and determined whether lack of functional MC4R conferred protection from weight loss during 50% calorie restriction. Though Mc4r^K314X/K314X rats showed low brown adipose Ucp1 expression and were less physically active than rats heterozygous for the mutation (Mc4r^+/K314X) or wild-type (Mc4r^+/+) rats, we found no evidence of lowered EE in Mc4r^K314X/K314X rats once body weight was taken into account using covariance. Mc4r^K314X/K314X rats had a significantly higher respiratory exchange ratio. Compared to Mc4r^+/+ rats, Mc4r^K314X/K314X and Mc4r^+/K314X rats lost less lean mass during calorie restriction, and less body mass when baseline weight was accounted for. Limited regional overexpression of Mc3r was found in the hypothalamus. Although lower physical activity levels in rats with nonfunctional MC4R did not result in lower total EE during free-fed conditions, rats lacking one or two functional copies of Mc4r showed conservation of mass, particularly lean mass, during energy restriction. This suggests that variants affecting MC4R function may contribute to individual differences in the metabolic response to food restriction.

Is Obesity Associated with Altered Energy Expenditure?

Historically, obese individuals were believed to have lower energy expenditure (EE) rates than nonobese individuals (normal and overweight), which, in the long term, would contribute to a positive energy balance and subsequent weight gain. The aim of this review was to critically appraise studies that compared measures of EE and its components, resting EE (REE), activity EE (AEE), and diet-induced thermogenesis (DIT), in obese and nonobese adults to elucidate whether obesity is associated with altered EE. Contrary to popular belief, research has shown that obese individuals have higher absolute REE and total EE. When body composition (namely the metabolically active component, fat-free mass) is taken into account, these differences between obese and nonobese individuals disappear, suggesting that EE in obese individuals is not altered. However, an important question is whether AEE is lower in obese individuals because of a decrease in overall physical activity or because of less energy expended while performing physical activity. AEE and DIT could be reduced in obese individuals, mostly because of unhealthy behavior (low physical activity, higher intake of fat). However, the current evidence does not support the hypothesis that obesity is sustained by lower daily EE or REE. Future studies, comparing EE between obese and nonobese and assessing potential physiologic abnormalities in obese individuals, should be able to better answer the question of whether these individuals have altered energy metabolism.

Worksite Physical Activity Intervention for Ambulatory Clinic Nursing Staff

Health behaviors, including physical activity (PA), of registered nurses (RNs) and medical assistants (MAs) are suboptimal but may improve with worksite programs. Using a repeated-measures crossover design, the authors explored if integrating a 6-month worksite non-exercise activity thermogenesis (NEAT) intervention, with and without personalized health coaching via text messaging into workflow could positively affect sedentary time, PA, and body composition of nursing staff without jeopardizing work productivity. Two ambulatory clinics were randomly assigned to an environmental NEAT intervention plus a mobile text message coaching for either the first 3 months (early texting group, n = 27) or the last 3 months (delayed texting group, n = 13), with baseline 3-month and 6-month measurements. Sedentary and PA levels, fat mass, and weight improved for both groups, significantly only for the early text group. Productivity did not decline for either group. This worksite intervention is feasible and may benefit nursing staff.

Associations among sedentary and active behaviours, body fat and appetite dysregulation: investigating the myth of physical inactivity and obesity

BACKGROUND

There is considerable disagreement about the association between free-living physical activity (PA) and sedentary behaviour and obesity. Moreover studies frequently do not include measures that could mediate between PA and adiposity. The present study used a validated instrument for continuous tracking of sedentary and active behaviours as part of habitual daily living, together with measures of energy expenditure, body composition and appetite dysregulation. This cross-sectional study tested the relationship between inactivity and obesity.

METHODS

71 participants (81.7% women) aged 37.4 years (±14) with a body mass index of 29.9 kg/m² (±5.2) were continuously monitored for 6-7 days to track free-living PA (light 1.5-3 metabolic equivalents (METs), moderate 3-6 METs and vigorous >6 METs) and sedentary behaviour (<1.5 METs) with the SenseWear Armband. Additional measures included body composition, waist circumference, cardiovascular fitness, total and resting energy expenditure, and various health markers. Appetite control was assessed by validated eating behaviour questionnaires.

RESULTS

Sedentary behaviour (11.06±1.72 h/day) was positively correlated with fat mass (r=0.50, p<0.001) and waist circumference (r=-0.65, p<0.001). Moderate-to-vigorous PA was negatively associated with fat mass (r=-0.72, p<0.001) and remained significantly correlated with adiposity after controlling for sedentary behaviour. Activity energy expenditure was positively associated with the level of PA and negatively associated with fat mass. Disinhibition and binge eating behaviours were positively associated with fat mass (r=0.58 and 0.47, respectively, p<0.001).

CONCLUSIONS

This study demonstrated clear associations among objective measures of PA (and sedentary behaviour), energy expenditure, adiposity and appetite control. The data indicate strong links between physical inactivity and obesity. This relationship is likely to be bidirectional.

Evaluation of the ability of three physical activity monitors to predict weight change and estimate energy expenditure

Activity monitors such as the Actical accelerometer, the Sensewear armband, and the Intelligent Device for Energy Expenditure and Activity (IDEEA) are commonly validated against gold standards (e.g., doubly labeled water, or DLW) to determine whether they accurately measure total daily energy expenditure (TEE) or activity energy expenditure (AEE). However, little research has assessed whether these parameters or others (e.g., posture allocation) predict body weight change over time. The aims of this study were to (i) test whether estimated energy expenditure or posture allocation from the devices was associated with weight change during and following a low-calorie diet (LCD) and (ii) compare free-living TEE and AEE predictions from the devices against DLW before weight change. Eighty-seven participants from 2 clinical trials wore 2 of the 3 devices simultaneously for 1 week of a 2-week DLW period. Participants then completed an 8-week LCD and were weighed at the start and end of the LCD and 6 and 12 months after the LCD. More time spent walking at baseline, measured by the IDEEA, significantly predicted greater weight loss during the 8-week LCD. Measures of posture allocation demonstrated medium effect sizes in their relationships with weight change. Bland-Altman analyses indicated that the Sensewear and the IDEEA accurately estimated TEE, and the IDEEA accurately measured AEE. The results suggest that the ability of energy expenditure and posture allocation to predict weight change is limited, and the accuracy of TEE and AEE measurements varies across activity monitoring devices, with multi-sensor monitors demonstrating stronger validity.

Hyperleptinemia During Pregnancy Decreases Adult Weight of Offspring and Is Associated With Increased Offspring Locomotor Activity in Mice

Pregnant women who are obese or have gestational diabetes mellitus have elevated leptin levels and their children have an increased risk for child and adult obesity. The goals of this study were to determine whether offspring weights are altered by maternal hyperleptinemia, and whether this occurs via behavioral changes that influence energy balance. We used 2 hyperleptinemic mouse models. The first was females heterozygous for a leptin receptor mutation (DB/+), which were severely hyperleptinemic, and that were compared with wild-type females. The second model was wild-type females infused with leptin (LEP), which were moderately hyperleptinemic, and were compared with wild-type females infused with saline (SAL). Total food consumption, food preference, locomotor activity, coordinated motor skills, and anxiety-like behaviors were assessed in wild-type offspring from each maternal group at 3 postnatal ages: 4-6, 11-13, and 19-21 weeks. Half the offspring from each group were then placed on a high-fat diet, and behaviors were reassessed. Adult offspring from both groups of hyperleptinemic dams weighed less than their respective controls beginning at 23 weeks of age, independent of diet or sex. Weight differences were not explained by food consumption or preference, because female offspring from hyperleptinemic dams tended to consume more food and had reduced preference for palatable, high-fat and sugar, food compared with controls. Offspring from DB/+ dams were more active than offspring of controls, as were female offspring of LEP dams. Maternal hyperleptinemia during pregnancy did not predispose offspring to obesity, and in fact, reduced weight gain.

Leanness and heightened nonresting energy expenditure: role of skeletal muscle activity thermogenesis

A high-calorie diet accompanied by low levels of physical activity (PA) accounts for the widespread prevalence of obesity today, and yet some people remain lean even in this obesogenic environment. Here, we investigate the cause for this exception. A key trait that predicts high PA in both humans and laboratory rodents is intrinsic aerobic capacity. Rats artificially selected as high-capacity runners (HCR) are lean and consistently more physically active than their low-capacity runner (LCR) counterparts; this applies to both males and females. Here, we demonstrate that HCR show heightened total energy expenditure (TEE) and hypothesize that this is due to higher nonresting energy expenditure (NREE; includes activity EE). After matching for body weight and lean mass, female HCR consistently had heightened nonresting EE, but not resting EE, compared with female LCR. Because of the dominant role of skeletal muscle in nonresting EE, we examined muscle energy use. We found that lean female HCR had higher muscle heat dissipation during activity, explaining their low economy of activity and high activity EE. This may be due to the amplified skeletal muscle expression levels of proteins involved in EE and reduced expression levels of proteins involved in energy conservation in HCR relative to LCR. This is also associated with an increased sympathetic drive to skeletal muscle in HCR compared with LCR. We find little support for the hypothesis that resting metabolic rate is correlated with maximal aerobic capacity if body size and composition are fully considered; rather, the critical factor appears to be activity thermogenesis.

A hybrid online intervention for reducing sedentary behavior in obese women

Sedentary behavior (SB) has emerged as an independent risk factor for cardiovascular disease and type 2 diabetes. While exercise is known to reduce these risks, reducing SB through increases in non-structured PA and breaks from sitting may appeal to obese women who have lower self-efficacy for PA. This study examined effects of a combined face-to-face and online intervention to reduce SB in overweight and obese women. A two-group quasi-experimental study was used with measures taken pre and post. Female volunteers (M age = 58.5, SD = 12.5 years) were enrolled in the intervention (n = 40) or waitlisted (n = 24). The intervention, based on the Social Cognitive Theory, combined group sessions with email messages over 6 weeks. Individualized feedback to support mastery and peer models of active behaviors were included in the emails. Participants self-monitored PA with a pedometer. Baseline and post measures of PA and SB were assessed by accelerometer and self-report. Standard measures of height, weight, and waist circumference were conducted. Repeated measures ANOVA was used for analyses. Self-reported SB and light PA in the intervention group (I) changed significantly over time [SB, F(1, 2) = 3.81, p = 0.03, light PA, F(1, 2) = 3.39, p = 0.04]. Significant Group × Time interactions were found for light PA, F(1, 63) = 5.22, p = 0.03, moderate PA, F(1, 63) = 3.90, p = 0.05, and for waist circumference, F(1, 63) = 16.0, p = 0.001. The intervention group decreased significantly while the comparison group was unchanged. Hybrid computer interventions to reduce SB may provide a non-exercise alternative for increasing daily PA and potentially reduce waist circumference, a risk factor for type 2 diabetes. Consumer-grade accelerometers may aide improvements to PA and SB and should be tested as part of future interventions.

Weight-loss induced changes in physical activity and activity energy expenditure in overweight and obese subjects before and after energy restriction

Activity energy expenditure (AEE) is the component of daily energy expenditure that is mainly influenced by the amount of physical activity (PA) and by the weight of the body displaced. This study aimed at analyzing the effect of weight loss on PA and AEE. The body weight and PA of 66 overweight and obese subjects were measured at baseline and after 12 weeks of 67% energy restriction. PA was measured using a tri-axial accelerometer for movement registration (Tracmor) and quantified in activity counts. Tracmor recordings were also processed using a classification algorithm to recognize 6 common activity types engaged in during the day. A doubly-labeled water validated equation based on Tracmor output was used to estimate AEE. After weight loss, body weight decreased by 13±4%, daily activity counts augmented by 9% (95% CI: +2%, +15%), and this increase was weakly associated with the decrease in body weight (R(2) = 7%; P<0.05). After weight loss subjects were significantly (P<0.05) less sedentary (-26 min/d), and increased the time spent walking (+11 min/d) and bicycling (+4 min/d). However, AEE decreased by 0.6±0.4 MJ/d after weight loss. On average, a 2-hour/day reduction of sedentary time by increasing ambulatory and generic activities was required to restore baseline levels of AEE. In conclusion, after weight loss PA increased but the related metabolic demand did not offset the reduction in AEE due to the lower body weight. Promoting physical activity according to the extent of weight loss might increase successfulness of weight maintenance.

The Travel—Obesity Connection: Discerning the Impacts of Commuting Trips with the Perspective of Individual Energy Expenditure and Time Use

It has been widely reported that individual travel has significant implications for obesity. In this research we try to clarify the connection between travel and obesity from an individual energy-expenditure perspective. It is hypothesized here that individual travel affects the likelihood of becoming obese not only directly through a reliance on automobile-based travel that requires low amounts of individual energy expenditure, but also indirectly through the fatigue and stress stemming from driving, which reduces time available for physical activities and exercise. We use the American Time Use Survey ( http://www.bls.gov/tus/ ) for 2003–08 and its Eating and Health Module for 2006 and 2007 to examine individual travel, energy expenditure, and obesity. Empirical analysis illustrates how individual body mass index (BMI) and individual travel are correlated and how this correlation can be explained from the perspective of individual energy expenditure. In addition, a distinction is drawn between commuting and noncommuting trips: Commuting trips have a relatively larger impact on individual BMI. Analysis results point to a potential to reduce obesity rates through planning efforts at the regional level.

Sitting time and health outcomes among Mexican origin adults: obesity as a mediator

Background

Sitting time and sedentary behaviors have been associated with adverse health outcomes including obesity, diabetes and cardiovascular disease (CVD) within non- Hispanic White populations. Similar associations have not been described within Hispanic populations despite their high CVD risk profile. This study aimed to assess the association between sitting time and obesity, self-reported diagnosed diabetes, hypertension and high cholesterol among a large cohort (N=11,268) of Mexican origin adults and to assess whether obesity mediated these associations.

Methods

Using a cross-sectional design, data collected between 2004 and 2010 were analyzed in late 2010. Regression analyses evaluated associations between self-reported daily sitting hours and disease outcomes, controlling for demographics, employment status, family disease history, and light, moderate and strenuous physical activity.

Results

Participants were mostly female (81.1%) Mexican origin adults. Sitting time was associated with increased odds of being obese, having diabetes and having hypertension, but not high cholesterol. Adjusted odds ratios of participants who reported sitting > 4 hours/day compared to those sitting 1-2 hours/day were for obesity OR=1.55 (95% CI 1.39, 1.73), p<.001, for diabetes OR=1.29 (95% CI, 1.09, 1.52), p=.003, for hypertension OR=1.17 (95% CI, 1.01, 1.37), p=.041. Associations controlled for physical activity and employment status. Effects on hypertension and diabetes were mediated by obesity.

Conclusions

Sitting time was significantly associated with detrimental health outcomes, independent of physical activity. Obesity mediated these relationships for diabetes and hypertension. Future research should assess whether interventions addressing sitting time are feasible and effective among Mexican origin populations.

Divergent skeletal muscle respiratory capacities in rats artificially selected for high and low running ability: a role for Nor1?

Inactivity-related diseases are becoming a huge burden on Western society. While there is a major environmental contribution to metabolic health, the intrinsic properties that predispose or protect against particular health traits are harder to define. We used rat models of inborn high running capacity (HCR) and low running capacity (LCR) to determine inherent differences in mitochondrial volume and function, hypothesizing that HCR rats would have greater skeletal muscle respiratory capacity due to an increase in mitochondrial number. Additionally, we sought to determine if there was a link between the expression of the orphan nuclear receptor neuron-derived orphan receptor (Nor)1, a regulator of oxidative metabolism, and inherent skeletal muscle respiratory capacity. LCR rats were 28% heavier (P < 0.0001), and fasting serum insulin concentrations were 62% greater than in HCR rats (P = 0.02). In contrast, HCR rats had better glucose tolerance and reduced adiposity. In the primarily oxidative soleus muscle, maximal respiratory capacity was 21% greater in HCR rats (P = 0.001), for which the relative contribution of fat oxidation was 20% higher than in LCR rats (P = 0.02). This was associated with increased citrate synthase (CS; 33%, P = 0.009) and β-hydroxyacyl-CoA (β-HAD; 33%, P = 0.0003) activities. In the primarily glycolytic extensor digitum longus muscle, CS activity was 29% greater (P = 0.01) and β-HAD activity was 41% (P = 0.0004) greater in HCR rats compared with LCR rats. Mitochondrial DNA copy numbers were also elevated in the extensor digitum longus muscles of HCR rats (35%, P = 0.049) and in soleus muscles (44%, P = 0.16). Additionally, HCR rats had increased protein expression of individual mitochondrial respiratory complexes, CS, and uncoupling protein 3 in both muscle types (all P < 0.05). In both muscles, Nor1 protein was greater in HCR rats compared with LCR rats (P < 0.05). We propose that the differential expression of Nor1 may contribute to the differences in metabolic regulation between LCR and HCR phenotypes.

Unstable shoes increase energy expenditure of obese patients

BACKGROUND

Ergonomic unstable shoes, which are widely available to the general population, could increase daily non-exercise activity thermogenesis as the result of increased muscular involvement. We compared the energy expenditure of obese patients during standing and walking with conventional flat-bottomed shoes versus unstable shoes.

METHODS

Twenty-nine obese patients were asked to stand quietly and to walk at their preferred walking speed while wearing unstable or conventional shoes. The main outcome measures were metabolic rate of standing and gross and net energy cost of walking, as assessed with indirect calorimetry.

RESULTS

Metabolic rate of standing was higher while wearing unstable shoes compared with conventional shoes (1.11 ± 0.20 W/kg(-1) vs 1.06 ± 0.23 W/kg(-1), P=.0098). Gross and net energy cost of walking were higher while wearing unstable shoes compared with conventional shoes (gross: 4.20 ± 0.42 J/kg(-1)/m(-1)vs 4.01 ± 0.39 J/kg(-1)/m(-1), P=.0035; net: 3.37 ± 0.41 J/kg(-1)/m(-1) vs 3.21 ± 0.37 J/kg(-1)/m(-1); P=.032).

CONCLUSION

In obese patients, it is possible to increase energy expenditure of standing and walking by means of ergonomic unstable footwear. Long-term use of unstable shoes may eventually prevent a positive energy balance.

Physical activity: the forgotten tool for type 2 diabetes management

Individuals who are currently sedentary, unfit, or overweight can benefit metabolically from simply taking breaks from sitting. Since avoidance of sedentary behavior appears to have a large impact on glycemic management, all individuals with type 2 diabetes should be encouraged to minimally engage in greater daily movement to better manage their diabetes and body weight. In addition, engaging in physical activity of any intensity (including low-intensity ones) likely positively impacts insulin action and blood glucose control acutely. Moreover, as long as total caloric expenditure during exercise is matched (i.e., total exercise dose), daily exercise may be done every other day instead with the same glycemic results, although at least 150 min of weekly physical activity is recommended. Both aerobic and resistance training are important for individuals with diabetes, and ideally a program that combines the two types of training should be undertaken to achieve maximal glycemic and other benefits. Once individuals have successfully implemented more daily movement into their lifestyle, they will be more likely to participate in structured forms of physical activity to gain additional benefits. All clinicians working with individuals with either type 2 diabetes or prediabetes should consider incorporating these suggestions into care plans to improve their patients' glycemic management.

Gait and Function in Class III Obesity

Walking, more specifically gait, is an essential component of daily living. Walking is a very different activity for individuals with a Body Mass Index (BMI) of 40 or more (Class III obesity) compared with those who are overweight or obese with a BMI between 26-35. Yet all obesity weight classes receive the same physical activity guidelines and recommendations. This observational study examined the components of function and disability in a group with Class III obesity and a group that is overweight or has Class I obesity. Significant differences were found between the groups in the areas of gait, body size, health condition, and activity capacity and participation. The Timed Up and Go test, gait velocity, hip circumference, and stance width appear to be most predictive of activity capacity as observed during gait assessment. The findings indicate that Class III-related gait is pathologic and not a normal adaptation.

How much locomotive activity is needed for an active physical activity level: analysis of total step counts

BACKGROUND

Although physical activity recommendations for public health have focused on locomotive activity such as walking and running, it is uncertain how much these activities contribute to overall physical activity level (PAL). The purpose of the present study was to determine the contribution of locomotive activity to PAL using total step counts measured in a calorimeter study.

METHODS

PAL, calculated as total energy expenditure divided by basal metabolic rate, was evaluated in 11 adult men using three different conditions for 24-hour human calorimeter measurements: a low-activity day (L-day) targeted at a low active level of PAL (1.45), and a high-frequency moderate activity day (M-day) or a high-frequency vigorous activity day (V-day) targeted at an active level of PAL (1.75). These subjects were permitted only light activities except prescribed activities. In a separate group of 41 adults, free-living PAL was evaluated using doubly-labeled water (DLW). In both experiments, step counts per day were also measured using an accelerometer.

RESULTS

In the human calorimeter study, PAL and step counts were 1.42 ± 0.10 and 8,973 ± 543 steps/d (L-day), 1.82 ± 0.14 and 29,588 ± 1,126 steps/d (M-day), and 1.74 ± 0.15 and 23,755 ± 1,038 steps/d (V-day), respectively. In the DLW study, PAL and step counts were 1.73 ± 0.15 and 10,022 ± 2,605 steps/d, and there was no significant relationship between PAL and daily step counts.

CONCLUSIONS

These results indicate that an enormous number of steps are needed for an active level of PAL if individuals extend physical activity-induced energy expenditure by only locomotive activity. Therefore, non-locomotive activity such as household activity should also play a significant role in increasing PAL under free-living conditions.

Identifying types of physical activity with a single accelerometer: evaluating laboratory-trained algorithms in daily life

Accurate identification of physical activity types has been achieved in laboratory conditions using single-site accelerometers and classification algorithms. This methodology is then applied to free-living subjects to determine activity behavior. This study is aimed at analyzing the reproducibility of the accuracy of laboratory-trained classification algorithms in free-living subjects during daily life. A support vector machine (SVM), a feed-forward neural network (NN), and a decision tree (DT) were trained with data collected by a waist-mounted accelerometer during a laboratory trial. The reproducibility of the classification performance was tested on data collected in daily life using a multiple-site accelerometer augmented with an activity diary for 20 healthy subjects (age: 30 ± 9; BMI: 23.0 ± 2.6 kg/m(2)). Leave-one-subject-out cross validation of the training data showed accuracies of 95.1 ± 4.3%, 91.4 ± 6.7%, and 92.2 ± 6.6% for the SVM, NN, and DT, respectively. All algorithms showed a significantly decreased accuracy in daily life as compared to the reference truth represented by the IDEEA and diary classifications (75.6 ± 10.4%, 74.8 ± 9.7%, and 72.2 ± 10.3%; p < 0.05). In conclusion, cross validation of training data overestimates the accuracy of the classification algorithms in daily life.

Advances in physical activity monitoring and lifestyle interventions in obesity: a review

Obesity represents a strong risk factor for developing chronic diseases. Strategies for disease prevention often promote lifestyle changes encouraging participation in physical activity. However, determining what amount of physical activity is necessary for achieving specific health benefits has been hampered by the lack of accurate instruments for monitoring physical activity and the related physiological outcomes. This review aims at presenting recent advances in activity-monitoring technology and their application to support interventions for health promotion. Activity monitors have evolved from step counters and measuring devices of physical activity duration and intensity to more advanced systems providing quantitative and qualitative information on the individuals' activity behavior. Correspondingly, methods to predict activity-related energy expenditure using bodily acceleration and subjects characteristics have advanced from linear regression to innovative algorithms capable of determining physical activity types and the related metabolic costs. These novel techniques can monitor modes of sedentary behavior as well as the engagement in specific activity types that helps to evaluate the effectiveness of lifestyle interventions. In conclusion, advances in activity monitoring have the potential to support the design of response-dependent physical activity recommendations that are needed to generate effective and personalized lifestyle interventions for health promotion.

Energy expenditure in adults living in developing compared with industrialized countries: a meta-analysis of doubly labeled water studies

BACKGROUND

There is an assumption that people in developing countries have a higher total energy expenditure (TEE) and physical activity level (PAL) than do people in developed nations, but few objective data for this assertion exist.

OBJECTIVE

We conducted a meta-analysis of TEE and PAL by using data from countries that have a low or middle human development index (HDI) compared with those with a high HDI to better understand how energy-expenditure variables are associated with development status and population differences in body size.

DESIGN

We performed a literature search for studies in which energy expenditure was measured by using doubly labeled water. Mean data on age, weight, body mass index (BMI; in kg/m(2)), TEE, and PAL were extracted, and HDI status was assessed. Pooled estimates of the mean effect by sex were obtained, and the extent to which age, weight, HDI status, and year of publication explained heterogeneity was assessed.

RESULTS

A total of 98 studies (14 studies from low- or middle-HDI countries) that represented 183 cohorts and 4972 individuals were included. Mean (±SE) BMI was lower in countries with a low or middle HDI than in those with a high HDI for both men and women (22.7 ± 1.0 compared with 26.0 ± 0.7, respectively, in men and 24.3 ± 0.7 compared with 26.6 ± 0.4, respectively, in women). In meta-regression models, there was an inverse association of age (P < 0.001) and a positive association of weight (P < 0.001) with TEE for both sexes; there was an association of age only in men with PAL (P < 0.001). There was no association of HDI status with either TEE or PAL.

CONCLUSION

TEE adjusted for weight and age or PAL did not differ significantly between developing and industrialized countries, which calls into question the role of energy expenditure in the cause of obesity at the population level.

Non-exercise physical activity in agricultural and urban people

With evidence that urbanisation is associated with obesity, diabetes, hypertension and cardiovascular disease, this article compares daily physical activity between rural and urban dwellers. Specifically, it examines habitual daily activity levels, non-exercise activity thermogenesis (NEAT) and energy expenditure in agricultural and urban Jamaicans and urban North Americans. Ambulation was 60 per cent greater in rural Jamaicans than in the urban dwellers (4675 ± 2261 versus 2940 ± 1120 ambulation-attributed arbitrary units (AU)/day; P = 0.001). Levels of ambulation in lean urban Jamaicans were similar to those in lean urban North Americans, whereas obese urban dwellers walked less than their lean urban counterparts (2198 ± 516 versus 2793 ± 774 AU/day; P = 0.01). The data with respect to daily sitting mirrored the walking data; obese Americans sat for almost four hours more each day than rural Jamaicans (562 ± 78 versus 336 ± 68 minutes/day; P < 0.001). Urbanisation is associated with low levels of daily activity and NEAT.

Sitting time is associated with weight, but not with weight gain in mid-aged Australian women

The aim of this study was to examine the associations between sitting time, weight, and weight gain in Australian women born in 1946-1951. Data were from 8,233 women who completed surveys for the Australian Longitudinal Study on Women's Health (ALSWH) in 2001, 2004, and 2007. Associations between sitting time and weight, and between sitting time and weight change in each 3-year period were examined using repeated measures modeling. The associations between weight and change in sitting time were also examined. Analyses were stratified for BMI categories: normal weight (18.5 <or= BMI < 25), overweight (25 <or= BMI < 30), and obese (BMI >or= 30). In cross-sectional models, each additional hour of sitting time was associated with 110 g (95% confidence interval (CI): 40-180) and 260 g (95% CI: 140-380) additional weight in overweight and obese women, respectively (fully adjusted model). In prospective analyses, sitting time was not consistently associated with weight change, after adjustment for other variables, and weight was not associated with change in sitting time over successive 3-year periods. In conclusion, although the cross-sectional associations between sitting time and weight were evident in overweight and obese women, there was no consistent association between sitting time and weight gain. A potential explanation is that prospective associations may only be apparent over longer periods of time. These results do not support a role for reducing sitting time as a short-term means of weight control in mid-aged women.

Spontaneous activity, economy of activity, and resistance to diet-induced obesity in rats bred for high intrinsic aerobic capacity

Though obesity is common, some people remain resistant to weight gain even in an obesogenic environment. The propensity to remain lean may be partly associated with high endurance capacity along with high spontaneous physical activity and the energy expenditure of activity, called non-exercise activity thermogenesis (NEAT). Previous studies have shown that high-capacity running rats (HCR) are lean compared to low-capacity runners (LCR), which are susceptible to cardiovascular disease and metabolic syndrome. Here, we examine the effect of diet on spontaneous activity and NEAT, as well as potential mechanisms underlying these traits, in rats selectively bred for high or low intrinsic aerobic endurance capacity. Compared to LCR, HCR were resistant to the sizeable increases in body mass and fat mass induced by a high-fat diet; HCR also had lower levels of circulating leptin. HCR were consistently more active than LCR, and had lower fuel economy of activity, regardless of diet. Nonetheless, both HCR and LCR showed a similar decrease in daily activity levels after high-fat feeding, as well as decreases in hypothalamic orexin-A content. The HCR were more sensitive to the NEAT-activating effects of intra-paraventricular orexin-A compared to LCR, especially after high-fat feeding. Lastly, levels of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in the skeletal muscle of HCR were consistently higher than LCR, and the high-fat diet decreased skeletal muscle PEPCK-C in both groups of rats. Differences in muscle PEPCK were not secondary to the differing amount of activity. This suggests the possibility that intrinsic differences in physical activity levels may originate at the level of the skeletal muscle, which could alter brain responsiveness to neuropeptides and other factors that regulate spontaneous daily activity and NEAT.

Poor prediction of resting energy expenditure in obese women by established equations

The objective of the study was to evaluate the accuracy of established prediction equations that calculate resting energy expenditure (REE) in obese women. This was a cross-sectional study. In 273 mildly to severely obese women (age, 41.7 +/- 13.2 years; body mass index, 42.8 +/- 7.0 kg/m(2)), REE was measured by indirect calorimetry (mREE), along with fat mass (FM) and fat-free mass (FFM) by bioelectrical impedance analysis. Eleven established equations were used to predict REE (pREE), with 9 equations basing on the anthropometric parameters body weight and height and 2 equations including body composition parameters (FM, FFM). All equations provided pREE values that significantly correlated with mREE (r > 0.66, P < .001), although 8 equations systematically underestimated mREE (P < .05). Of note, even the best equation was not able to accurately predict mREE with a deviation of less than +/-10% in more than 70% of the tested women. Furthermore, equations using body composition data were not superior in predicting REE as compared with equations exclusively including anthropometric variables. Multiple linear regression analyses revealed 2 new equations--one including body weight and age and another including FM, FFM, and age--that explained 56.9% and 57.2%, respectively, of variance in mREE. However, when these 2 new equations were applied to an independent sample of 33 obese women, they also provided an accurate prediction (+/-10%) of mREE in only 56.7% and 60.6%, respectively, of the women. Data show that an accurate prediction of REE is not feasible using established equations in obese women. Equations that include body composition parameters as assessed by bioelectrical impedance analysis do not increase the accuracy of prediction. Based on our results, we conclude that calculating REE by standard prediction equations does not represent a reliable alternative to indirect calorimetry for the assessment of REE in obese women.

Sedentariness at work: how much do we really sit?

Sedentariness is associated with obesity. We examined whether people with sedentary jobs are equally inactive during their work days and leisure days. We enrolled 21 subjects of varying weight and body fat (11 men:10 women, 38 +/- 8 years, 83 +/- 17 kg, BMI 28 +/- 5 kg/m(2), 29 +/- 11 fat kg, 35 +/- 9% fat). All subjects continued their usual work and leisure-time activities whilst we measured daily activity and body postures for 10 days. The data supported our hypothesis that people sit more at work compared to leisure (597 +/- 122 min/day cf 484 +/- 83 min/day; P < 0.0001). The mean difference was 110 +/- 99 min/day. Similarly, work days were associated with less standing (341 +/- 97 min/day; P = 0.002) than leisure days (417 +/- 101 min/day). Although the walking bouts did not differ significantly between work and leisure (46 +/- 9 vs. 42 +/- 9 walking bouts/day); the mean free-living velocity of a walk at work was 1.08 +/- 0.28 mph and on leisure days was 0.94 +/- 0.24 mph (P = 0.03) and the average time spent walking was 322 +/- 91 min on work days and 380 +/- 108 min on leisure days (P = 0.03). Estimates of the daily energetic cost of walking approximated 527 +/- 220 kcal/day for work days and 586 +/- 326 kcal/day for leisure days (r = 0.72, P < 0.001). Work days are associated with more sitting and less walking/standing time than leisure days. We suggest a need to develop approaches to free people from their chairs and render them more active.

The impact of obesity on the mid-term outcome of cementless total knee replacement

We evaluated 535 consecutive primary cementless total knee replacements (TKR). The mean follow-up was 9.2 years (0.3 to 12.9) and information on implant survival was available for all patients. Patients were divided into two groups: 153 obese patients (BMI ≥ 30) and 382 non-obese (BMI < 30). A case-matched study was performed on the clinical and radiological outcome, comparing 50 knees in each group. We found significantly lower mean improvements in the clinical score (p = 0.044) and lower post-operative total clinical scores in the obese group (p = 0.041). There was no difference in the rate of radiological osteolysis or lucent lines, and no difference in alignment. Log rank test for survival showed no significant differences between the groups (p = 0.167), with a ten-year survival rate of 96.4% (95% confidence interval (CI) 92 to 99) in the obese and 98% (95% CI 96 to 99) in the non-obese.

The mid-term survival of TKR in the obese and the non-obese are comparable, but obesity appears to have a negative effect on the clinical outcome. However, good results and high patient satisfaction are still to be expected, and it would seem unreasonable to deny patients a TKR simply on the basis of a BMI indicating obesity.

Endurance capacity, not body size, determines physical activity levels: role of skeletal muscle PEPCK

Some people remain lean despite pressure to gain weight. Lean people tend to have high daily activity levels, but the source of this increased activity is unknown. We found that leanness cannot be accounted for by increased weight-corrected food intake in two different types of lean rats. As previously reported in lean people, we found that lean rats had higher daily activity levels; lean rats also expended more energy. These lean rats were developed through artificial selection for high aerobic endurance capacity. To test whether our findings extended to a human population, we measured endurance capacity using a VO_2max treadmill test and daily activity in a group of non-exercising individuals. Similar to lean rats selectively bred for endurance capacity, our study revealed that people with higher VO_2max also spent more time active throughout the day. Hence, endurance capacity may be the trait that underlies both physical activity levels and leanness. We identified one potential mechanism for the lean, active phenotype in rats, namely high levels of skeletal muscle PEPCK. Therefore, the lean phenotype is characterized by high endurance capacity and high activity and may stem from altered skeletal muscle energetics.

Validity of resting energy expenditure estimated by an activity monitor compared to indirect calorimetry

The use of activity monitors (triaxial accelerometers) to estimate total energy expenditure in kilocalories is dependent on the estimation of resting energy expenditure (REE). However, the REE estimated by activity monitors has not been validated against more precise techniques, such as indirect calorimetry (IC). Therefore, the objective of the present study was to compare REE estimated by the Actical activity monitor (ActMon) to that measured by IC and standard prediction equations of REE. Fifty healthy adults between 18 and 43 years of age were measured for weight and percentage of body fat using a digital scale and bioelectrical impedance. The REE estimated by the ActMon was only 129 kJ/d higher, but not statistically different (P>0·05), than the REE measured with IC. Using multiple linear regression, there was a positive relationship for men, but not for women, between fat mass (kg) and percentage of body fat and the difference in REE estimated by the ActMon compared to IC (P < 0·001). Therefore, in the cohort studied, the use of an activity monitor to estimate REE is valid when compared to IC, but not to a standard prediction equation of REE.