Physical activity in the treatment of obesity: beyond body weight reduction

Acceptability and Usability of a Theory-Driven Intervention via Email to Promote Physical Activity in Women Who Are Overweight or Obese: Substudy Within a Randomized Controlled Trial

BACKGROUND

Insufficient physical activity (PA) and excess weight increase illness risk for women. Face-to-face interventions can increase PA levels; however, they are often inaccessible. With growing interest in digital interventions, a Self-Determination Theory (SDT)-driven intervention was developed and delivered via email to promote PA in women who were insufficiently active and overweight or obese.

OBJECTIVE

This substudy explores users' perspectives about the acceptability and usability of the intervention, which was coupled with a wearable activity monitor and PA recommendations.

METHODS

A 3-arm, parallel group, randomized controlled trial (unblinded) was conducted in Ontario, Canada. Recruitment occurred from September 2018 to March 2019 via advertising through social media, web-based boards, and posters in publicly accessible areas. In total, 47 women with a BMI of ≥25 kg/m2 who were not meeting the Canadian PA guidelines were randomly assigned to 1 of 3 arms (arm 1: n=15, 32%; arm 2: n=16, 34%; arm 3: n=16, 34%). This substudy focused on the 15 participants allocated to the main intervention arm. Participants received an automated intervention consisting of (1) 6 weekly emails, (2) a Polar Electro Inc A300 activity monitor (with access to the Polar Flow website and companion smartphone app), and (3) a copy of the Canadian PA guidelines for adults. Emails were developed using SDT and designed to enhance autonomous motivation by fostering the psychological needs of competence, autonomy, and relatedness. Well-established motivational and behavior change techniques were embedded in the emails to promote needs satisfaction. After the intervention (ie, 7 weeks after randomization), participants were invited to complete a web-based acceptability and usability survey containing open-ended and closed-ended questions; responses were analyzed using descriptive and content analyses, respectively.

RESULTS

The analyses included data from 93% (14/15) of the women (age: mean 33.4, SD 7.5; range 24-44 years; BMI: mean 31.3, SD 5.8 kg/m2; range 25-40.5 kg/m2) who received the main intervention and completed the postintervention survey. Open-ended responses indicated that participants were generally satisfied with the intervention and appreciated that emails prompted self-reflection, kept them on track and accountable, provided informational support, and were nonpressuring. Furthermore, they suggested that the monitor was "enjoyable" and "helpful"; quantitative data corroborated this, as 71% (10/14) said that the monitor was "very valuable/absolutely valuable," 71% (10/14) would "very probably/definitely" still use one, and 86% (12/14) wore it for ≥5 days per week for ≥8 hours per day and checked it "occasionally/frequently/very frequently." Potential threats to acceptability included "long" and "text-heavy" emails; lack of personal contact; and cumbersome, unaesthetic monitors.

CONCLUSIONS

Results suggest that this SDT-driven, email-delivered intervention may be an acceptable low-contact approach to promote PA in women who are overweight or obese and insufficiently active; however, improvements are warranted and studies ascertaining its effectiveness are needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03601663; http://clinicaltrials.gov/ct2/show/NCT03601663.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.1177/20552076221093134.

The Effect of Aerobic Exercise on Variation of Oxidative Stress, hs-CRP and Cortisol Induced by Sleep Deficiency

The aim of this study was to investigate the impact of sleep deficiency (SD) on oxidative stress, hs-CRP and cortisol levels and to examine the effects of different intensities of aerobic exercise on these parameters under SD conditions. Thirty-two healthy male university students participated in the study and underwent both normal sleep (NS, 8 h of sleep per night for 3 consecutive days) and SD (4 h of sleep per night for 3 consecutive days). After the SD period, the participants performed treatment for 30 min according to their assigned group [sleep supplement after SD (SSD), low-intensity aerobic exercise after SD (LES), moderate-intensity aerobic exercise after SD (MES), high-intensity aerobic exercise after SD (HES)]. Sleep-related factors were measured at NS and SD, while oxidative stress, hs-CRP and cortisol levels were measured at NS, SD and immediately after treatment by group (AT). The results showed that actual total sleep time (ATST) was significantly reduced during SD compared to NS (p < 0.001), while the visual analogue scale (VAS) and Epworth sleepiness scale (ESS) were significantly increased during SD compared to NS (p < 0.001). The difference in reactive oxygen metabolites (d-ROMs) and cortisol levels showed a significant interaction effect (p < 0.01, p < 0.001, respectively), with LES showing a decrease in d-ROMs and cortisol levels compared to SD (p < 0.05). Similarly, SSD showed a decrease in cortisol levels compared to SD (p < 0.05), while HES led to a significant increase in d-ROMs and cortisol levels compared to SD (p < 0.05). Biological antioxidant potential (BAP) and hs-CRP did not show any significant effect (p > 0.05). These results suggest that LES is the most effective exercise intensity for mitigating the negative effects of SD.

Prevalence of Emotional Eating in Groups of Students with Varied Diets and Physical Activity in Poland

Background: Emotional eating (EE) is not a separate eating disorder, but rather a type of behavior within a group of various eating behaviors that are influenced by habits, stress, emotions, and individual attitudes toward eating. The relationship between eating and emotions can be considered on two parallel levels: psychological and physiological. In the case of the psychological response, stress generates a variety of bodily responses relating to coping with stress. Objective: Therefore, the main objective of this study was to evaluate and compare the prevalence of emotional eating in groups of students in health-related and non-health-related fields in terms of their differential health behaviors—diet and physical activity levels. Material and Methods: The cross-sectional survey study included 300 individuals representing two groups of students distinguished by their fields of study—one group was in health-related fields (HRF) and the other was in non-health-related fields (NRF). The study used standardized questionnaires: the PSS-10 and TFEQ-13. Results: The gender of the subjects was as follows: women, 60.0% (174 subjects) (HRF: 47.1%, n= 82; NRF: 52.9%, n = 92); men, 40.0% (116 subjects) (HRF: 53.4%, n = 62; NRF: 46.6%, n = 54). The age of the subjects was 26 years (±2 years). Based on the results of the TFEQ-13, among 120 subjects (41.4%) there were behaviors consistent with limiting food intake (HRF: 72.4%; NRF: 11.0%), while 64 subjects (20.7%) were characterized by a lack of control over food intake (HRF: 13.8%, 20 subjects; NRF: 27.4%, 20 subjects). Emotional eating was characteristic of 106 students (37.9%), with the NRF group dominating (61.6%, n = 90). It was observed that a high PSS-10 score is mainly characteristic of individuals who exhibit EE. Conclusions: The results obtained in the study indicate that lifestyle can have a real impact on the development of emotional eating problems. Individuals who are characterized by elevated BMI values, unhealthy diets, low rates of physical activity, who underestimate meal size in terms of weight and calories, and have high-stress feelings are more likely to develop emotional eating. These results also indicate that further research in this area should be undertaken to indicate whether the relationships shown can be generalized.

Effects of a 10-Week Physical Activity Intervention on Asylum Seekers’ Physiological Health

Introduction: The rise in armed conflicts has contributed to an increase in the number of asylum seekers. Prolonged asylum processes may negatively affect asylum seekers’ health and lead to inactivity. Studies show that physical activity interventions are associated with improvements in health outcomes. However, there are a limited number of studies investigating the associations of physical activity on asylum seekers’ health. Methods: Participants (263 males and 204 females), mostly from Syria, were assessed before and after a 10-week intervention for VO₂ max, body mass index (BMI), skeletal muscle mass (SMM), body fat, and visceral fat. Linear mixed models were used to test differences within groups, and a linear regression model analysis was performed to test whether physiological variables predicted adherence. Results: Participants’ VO₂ max increased: males by 2.96 mL/min/kg and females 2.57 mL/min/kg. Increased SMM percentages were seen in both genders: females by 0.38% and males 0.23%. Visceral fat area decreased: males by 0.73 cm² and females 5.44 cm². Conclusions: Participants showed significant increases in VO2 max and SMM and decreased visceral fat. This study provides an insight into asylum seekers’ health and serves as a starting point to new interventions in which physical activity is used as a tool to promote and improve vulnerable populations’ health.

Adipose Tissue Inflammation and Cardiovascular Disease: An Update

PURPOSE OF REVIEW

The obesity epidemic is on the rise, and while it is well known that obesity is associated with an increase in cardiovascular risk factors such as type 2 diabetes mellitus, hypertension, and obstructive sleep apnea, recent data has highlighted that the degree and type of fat distribution may play a bigger role in the pathogenesis of cardiovascular disease (CVD) than body mass index (BMI) alone. We aim to review updated data on adipose tissue inflammation and distribution and CVD.

RECENT FINDINGS

We review the pathophysiology of inflammation secondary to adipose tissue, the association of obesity-related adipokines and CVD, and the differences and significance of brown versus white adipose tissue. We delve into the clinical manifestations of obesity-related inflammation in CVD. We discuss the available data on heterogeneity of adipose tissue-related inflammation with a focus on subcutaneous versus visceral adipose tissue, the differential pathophysiology, and clinical CVD manifestations of adipose tissue across sex, race, and ethnicity. Finally, we present the available data on lifestyle modification, medical, and surgical therapeutics on reduction of obesity-related inflammation. Obesity leads to a state of chronic inflammation which significantly increases the risk for CVD. More research is needed to develop non-invasive VAT quantification indices such as risk calculators which include variables such as sex, age, race, ethnicity, and VAT concentration, along with other well-known CVD risk factors in order to comprehensively determine risk of CVD in obese patients. Finally, pre-clinical biomarkers such as pro-inflammatory adipokines should be validated to estimate risk of CVD in obese patients.

Physical activity motives, barriers, and preferences in people with obesity: A systematic review

Background

Although the benefits of physical activity (PA) are well known, physical inactivity is highly prevalent among people with obesity. The objective of this systematic review was to i) appraise knowledge on PA motives, barriers, and preferences in individuals with obesity, and ii) quantify the most frequently reported PA motives, barriers and preferences in this population.

Methods

Six databases (Pubmed, CINAHL, Psyarticle, SportDiscus, Web of science and Proquest) were searched by independent reviewers to identify relevant quantitative or qualitative articles reporting PA motives, barriers or preferences in adults with body mass index ≥ 30 kg/m² (last searched in June 2020). Risk of bias for each study was assessed by two independent reviewers with the Mixed Methods Appraisal Tool (MMAT).

Results

From 5,899 papers identified, a total of 27 studies, 14 quantitative, 10 qualitative and 3 mixed studies were included. About 30% of studies have a MMAT score below 50% (k = 8). The three most reported PA motives in people with obesity were weight management, energy/physical fitness, and social support. The three most common PA barriers were lack of self-discipline/motivation, pain or physical discomfort, and lack of time. Based on the only 4 studies available, walking seems to be the preferred mode of PA in people with obesity.

Conclusions

Weight management, lack of motivation and pain are key PA motives and barriers in people with obesity, and should be addressed in future interventions to facilitate PA initiation and maintenance. Further research is needed to investigate the PA preferences of people with obesity.

Effects of early-life exposure to Western diet and voluntary exercise on adult activity levels, exercise physiology, and associated traits in selectively bred High Runner mice

Exercise behavior is under partial genetic control, but it is also affected by numerous environmental factors, potentially including early-life experiences whose effects persist into adulthood. We studied genetic and early-life environmental effects on wheel-running behavior in a mouse model that includes four replicate high runner (HR) lines selectively bred for increased voluntary wheel running as young adults and four non-selected control (C) lines. In a full factorial design, mice from each line were granted wheel access or not and administered either standard or Western diet (WD) from weaning (3 weeks old) to 6 weeks of age (sexual maturity). In addition to acute effects, after a washout period of 8 weeks (∼6 human years) in which all mice had standard diet and no wheel access, we found both beneficial and detrimental effects of these early-life exposures. During the first week of treatments, WD increased distance run by 29% in C mice and 48% in HR mice (significant Diet × Linetype interaction), but diet effects disappeared by the third week. Across the three weeks of juvenile treatment, WD significantly increased fat mass (with lean mass as a covariate). Tested as adults, early-life exercise increased wheel running of C mice but not HR mice in the first week. Early-life exercise also reduced adult anxiety-like behavior and increased adult fasted blood glucose levels, triceps surae mass, subdermal fat pad mass, and brain mass, but decreased heart ventricle mass. Using fat mass as a covariate, early-life exercise treatment increased adult leptin concentration. In contrast, early-life WD increased adult wheel running of HR mice but not C mice. Early-life WD also increased adult lean mass and adult preference for Western diet in all groups. Surprisingly, early-life treatment had no significant effect on adult body fat or maximal aerobic capacity (VO2max). No previous study has tested for combined or interactive effects of early-life WD and exercise. Our results demonstrate that both factors can have long-lasting effects on adult voluntary exercise and related phenotypes, and that these effects are modulated by genetic background. Overall, the long-lasting effects of early-life exercise were more pervasive than those of WD, suggesting critical opportunities for health intervention in childhood habits, as well as possible threats from modern challenges. These results may be relevant for understanding potential effects of activity reductions and dietary changes associated with the obesity epidemic and COVID-19 pandemic.

Walking in the Light: How History of Physical Activity, Sunlight, and Vitamin D Account for Body Fat-A UK Biobank Study

OBJECTIVE

The high prevalence of vitamin D deficiency and obesity drives the need for successful strategies that elevate vitamin D levels, prevent adipogenesis, and stimulate lipolysis. This study provides a theoretical model to evaluate how physical activity (PA) and sunlight exposure influence serum vitamin D levels and regional adiposity. This study hypothesized a posteriori that sunlight is associated with undifferentiated visceral adiposity by increasing the ratio of brown to white adipose tissue.

METHODS

Using 10-year longitudinal data, accelerometry, a sun-exposure questionnaire, and regional adiposity quantified by dual-energy x-ray absorptiometry imaging, a structural-equation mediation model of growth curves was constructed with a data-driven methodology.

RESULTS

Sunlight and PA conjointly increased serum vitamin D. Changes in vitamin D levels partially mediated how sunlight and PA impacted adiposity in visceral and subcutaneous regions within a subjective PA model. In an objective PA model, vitamin D was a mediator for subcutaneous regions only. Interestingly, sunlight was associated with less adiposity in subcutaneous regions but greater adiposity in visceral regions.

CONCLUSIONS

Sunlight and PA may increase vitamin D levels. For the first time, this study characterizes a positive association between sunlight and visceral adiposity. Further investigation and experimentation are necessary to clarify the physiological role of sunlight exposure on adipose tissue.

Waist circumference as a vital sign in clinical practice: a Consensus Statement from the IAS and ICCR Working Group on Visceral Obesity

Despite decades of unequivocal evidence that waist circumference provides both independent and additive information to BMI for predicting morbidity and risk of death, this measurement is not routinely obtained in clinical practice. This Consensus Statement proposes that measurements of waist circumference afford practitioners with an important opportunity to improve the management and health of patients. We argue that BMI alone is not sufficient to properly assess or manage the cardiometabolic risk associated with increased adiposity in adults and provide a thorough review of the evidence that will empower health practitioners and professional societies to routinely include waist circumference in the evaluation and management of patients with overweight or obesity. We recommend that decreases in waist circumference are a critically important treatment target for reducing adverse health risks for both men and women. Moreover, we describe evidence that clinically relevant reductions in waist circumference can be achieved by routine, moderate-intensity exercise and/or dietary interventions. We identify gaps in the knowledge, including the refinement of waist circumference threshold values for a given BMI category, to optimize obesity risk stratification across age, sex and ethnicity. We recommend that health professionals are trained to properly perform this simple measurement and consider it as an important 'vital sign' in clinical practice.

Visceral and ectopic fat, atherosclerosis, and cardiometabolic disease: a position statement

Findings from epidemiological studies over the past 30 years have shown that visceral adipose tissue, accurately measured by CT or MRI, is an independent risk marker of cardiovascular and metabolic morbidity and mortality. Emerging evidence also suggests that ectopic fat deposition, including hepatic and epicardial fat, might contribute to increased atherosclerosis and cardiometabolic risk. This joint position statement from the International Atherosclerosis Society and the International Chair on Cardiometabolic Risk Working Group on Visceral Obesity summarises the evidence for visceral adiposity and ectopic fat as emerging risk factors for type 2 diabetes, atherosclerosis, and cardiovascular disease, with a focus on practical recommendations for health professionals and future directions for research and clinical practice. We discuss the measurement of visceral and ectopic fat, pathophysiology and contribution to adverse health outcomes, response to treatment, and lessons from a public health programme targeting visceral and ectopic fat. We identify knowledge gaps and note the need to develop simple, clinically applicable tools to be able to monitor changes in visceral and ectopic fat over time. Finally, we recognise the need for public health messaging to focus on visceral and ectopic fat in addition to excess bodyweight to better combat the growing epidemic of obesity worldwide.

Effect of Exercise and Pharmacological Interventions on Visceral Adiposity: A Systematic Review and Meta-analysis of Long-term Randomized Controlled Trials

OBJECTIVE

To assess the effectiveness of exercise and pharmacotherapy interventions in reducing visceral adipose tissue (VAT).

PATIENTS AND METHODS

A systematic search of Ovid MEDLINE, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov, New York Academy of Science Grey Literature Report, and OpenGrey was combined with hand searches of existing literature. A total of 2515 titles and abstracts were reviewed. Only randomized controlled trials evaluating the effectiveness of monitored exercise or pharmacological interventions in reducing VAT by using computed tomography or magnetic resonance imaging during a sustained intervention period (≥6 months) were included. Data were independently extracted by reviewers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and assessed for quality and risk of bias. Separate analyses for each intervention were performed using random effect models, with pooled estimates of the change in VAT area (in centimeters squared) from baseline to follow-up reported as standardized mean difference (SMD; with 95% CI).

RESULTS

A total of 3602 participants from 17 randomized controlled trials were included in the final analysis. Both exercise and pharmacological interventions were associated with significant reductions in VAT: small reduction with pharmacological interventions (SMD, -0.27; 95% CI, -0.47 to -0.07; P=.02) and more substantial reductions with exercise interventions (SMD, -0.54; 95% CI, -0.63 to -0.46; P<.001). The mean absolute VAT reduction was greater in pharmacological trials than in exercise trials. Meta-regression exhibited a linear correlation between VAT and weight loss (R²=0.52 for exercise and R²=0.88 for pharmacological interventions), but VAT reduction relative to weight loss differed by intervention type.

CONCLUSION

Exercise interventions resulted in greater reduction in VAT relative to weight loss than did pharmacological interventions. A preferential reduction in VAT may be clinically meaningful when monitoring success of interventions because weight loss alone may underestimate benefits.

Points-based physical activity: a novel approach to facilitate changes in body composition in inactive women with overweight and obesity

Background

Physical activity (PA) interventions for the promotion of weight-management may benefit from increased choice and flexibility to overcome commonly-perceived barriers to PA. The aim of this study was to investigate the effects of a novel “points-based” approach to PA on body composition in inactive women, who are overweight or obese.

Methods

Seventy-six overweight or obese, inactive women were randomly allocated to one of three conditions: ‘Points-based’ PA (PBPA; 30 “PA points”•week^− 1), Structured exercise (StructEx; 150 min moderate-intensity exercise•week^− 1) or control (CONT; continue habitual inactive lifestyle) for a 24-week intervention. PA points for activities were adapted from MET values, and 30 points was equivalent to 150 min of brisk walking. Measures of body composition (dual-energy x-ray absorptiometry) and anthropometry were obtained at weeks 0, 4, 12 and 24. Self-report activities were recorded weekly, with objective measures of PA (tri-axial accelerometry) and self-report measures of food intake obtained at weeks 0 and 24.

Results

Fifty-eight women completed the study and provided data for primary outcomes. Of these, n = 41 and n = 19 provided data for food intake and objectively assessed PA. Mixed-design ANOVAs demonstrated that those in PBPA achieved a significant weight-loss at 24 weeks of − 3.3 ± 5.9 kg (− 3.4 ± 7.1%, p = 0.004). Waist circumference was reduced in PBPA at 24 weeks (− 2.8 ± 4.6 cm), compared with CONT (+ 2.1 ± 6.6 cm, p = 0.024). There was a trend for greater reductions in fat mass for those in PBPA vs. CONT (− 2.3 ± 4.6 kg vs. + 0.1 ± 2.0 kg, p = 0.075). Android fat was reduced in PBPA at both 12 weeks (− 6.1 ± 12.6%, p = 0.005) and 24 weeks (− 10.1 ± 18.4%, p = 0.005), while there was a trend for greater reductions in visceral adipose tissue in PBPA (− 5.8 ± 26.0%) vs. CONT at 24 weeks (+ 7.8 ± 18.3%, p = 0.053). Body composition, body weight and waist circumference were unchanged in StructEx. There were trends for increases in light-activity and reductions in sedentary time in PBPA. There was a trend for a reduction in daily energy intake of − 445 ± 564 kcal (p = 0.074), and a significant reduction in daily fat intake (p = 0.042) in PBPA.

Conclusion

A “points-based” approach to physical activity appears to be an effective strategy for inducing modest reductions in body weight and body fat in inactive women with overweight and obesity.

Trial registration

NCT02020239. Registered 12th December 2013.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5125-2) contains supplementary material, which is available to authorized users.

Does Perceived Safety Modify the Effectiveness of a Walking-Group Intervention Designed to Promote Physical Activity?

PURPOSE

To examine whether perceived safety modified the effectiveness of the Walk Your Heart to Health (WYHH) intervention in promoting physical activity and reducing central adiposity in predominantly non-Latino black (henceforth black) and Latino communities.

DESIGN

Generalized estimation equations were used to assess modifying effects of perceived safety on the route and perceived neighborhood safety on (1) WYHH participation at 8 weeks and 32 weeks, (2) associations between participation and physical activity, and (3) associations between physical activity and central adiposity.

SETTING

Community-based and faith-based organizations in black and Latino communities.

PARTICIPANTS

There were 603 adults, aged 18 years and older, who were predominantly black, Latino, and female.

MEASURES

Participation and physical activity (piezoelectric pedometer) were measured at each walking session. Perceived safety on the route (questionnaire), perceived neighborhood safety (questionnaire), and waist circumference were measured at baseline, 8 weeks, and 32 weeks.

ANALYSIS

Secondary analysis of repeated measures using generalized estimation equations.

RESULTS

Retention was 90% at 8 weeks and 64% at 32 weeks. Perceived safety on the route, but not perceived neighborhood safety, dampened participation at 8 weeks but not 32 weeks. Consistent participation in the intervention increased physical activity and reduced central adiposity irrespective of perceived safety on the walking route or perceived neighborhood safety.

CONCLUSION

Efforts to improve safety in conjunction with interventions focused on increasing physical activity can work toward improving physical activity for blacks and Latinos, leading to a myriad of improved health outcomes including reduced central adiposity.

Relationships Among Factors Relevant to Abdominal Fat and Age-Related Hearing Loss

Objectives

Metabolic syndrome is related with abdominal fat and with age-related hearing loss (ARHL). In this study, we evaluated the association between a variety of factors relevant to abdominal fat (FRAs) and hearing thresholds.

Methods

We reviewed retrospectively the medical records of 2,602 subjects aged over 40 years with symmetrical sensorineural hearing loss who underwent abdominal fat computed tomography (CT) scans. Univariate and multivariate linear regression analyses were used to demonstrate the association between each FRA and hearing thresholds at low and high frequencies.

Results

Four of 5 FRAs were associated with hearing thresholds at high frequencies in males. All FRAs examined showed a relationship with hearing thresholds at low frequencies in females. Diabetes mellitus (DM) among clinical factors and visceral adipose tissue (VAT) among the 5 FRAs were the most reflective of hearing thresholds in both males and females.

Conclusion

We found that FRAs were associated with hearing loss with frequency specific characteristics according to sex and reinforced that DM and VAT is particularly an important role for hearing.

Associations among self-perceived work and life stress, trouble sleeping, physical activity, and body weight among Canadian adults

We investigated the associations among self-perceived work and life stress, trouble sleeping, physical activity and body weight among Canadian adults, and tested whether trouble sleeping and physical activity moderated the relationship between work/life stress and body weight, and whether work/life stress and physical activity moderated the relationship between trouble sleeping and body weight. Data on 13,926 Canadian adults aged 20years and older were derived from the nationally representative 2012 Canadian Community Health Survey. After adjusting for age, sex, education level, household income, marital status and job insecurity, self-perceived work and life stress and trouble sleeping were associated with a higher BMI. The associations of work and life stress with higher BMI were independent of trouble sleeping and physical activity in addition to other covariates, while that of trouble sleeping and higher BMI was independent of work and life stress. Results further indicated that trouble sleeping among inactive participants was related to a higher BMI; however, this relationship was almost null for adults who self-reported being physically active for about 8h/week. These findings suggest that work and life stress are both associated with excess weight in adults, regardless of physical activity level, while the link of trouble sleeping with BMI varies by physical activity level. Future research is necessary to determine whether reducing work and life stress and improving sleep habits would benefit the prevention of weight gain and obesity.

Exercise as medicine - evidence for prescribing exercise as therapy in 26 different chronic diseases

This review provides the reader with the up-to-date evidence-based basis for prescribing exercise as medicine in the treatment of 26 different diseases: psychiatric diseases (depression, anxiety, stress, schizophrenia); neurological diseases (dementia, Parkinson's disease, multiple sclerosis); metabolic diseases (obesity, hyperlipidemia, metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes, type 1 diabetes); cardiovascular diseases (hypertension, coronary heart disease, heart failure, cerebral apoplexy, and claudication intermittent); pulmonary diseases (chronic obstructive pulmonary disease, asthma, cystic fibrosis); musculo-skeletal disorders (osteoarthritis, osteoporosis, back pain, rheumatoid arthritis); and cancer. The effect of exercise therapy on disease pathogenesis and symptoms are given and the possible mechanisms of action are discussed. We have interpreted the scientific literature and for each disease, we provide the reader with our best advice regarding the optimal type and dose for prescription of exercise.

Healthy obesity as an intermediate state of risk: a critical review

Obesity is a top public health priority but interventions to reverse the condition have had limited success. About one-in-three obese adults are free of metabolic risk factor clustering and are considered 'healthy', and much attention has focused on the implications of this state for obesity management. Areas covered: We searched for individual studies, systematic reviews, and meta-analyses which examined correlates and outcomes of metabolically healthy obesity. We discuss the key roles of fat distribution and physical activity in determining healthy vs. unhealthy obesity and report a greatly increased risk of incident type 2 diabetes associated with healthy obesity vs. healthy normal weight, among other outcomes. We argue that despite inconsistencies in the definition, patterns across studies clearly show that healthy obesity is a state of intermediate disease risk. Expert commentary: Given the current state of population-level evidence, we conclude that obesity and metabolic dysfunction are inseparable and that healthy obesity is best viewed only as a state of relative health but not of absolute health. We recommend that weight loss through energy restriction be a stand-alone target in addition to increased physical activity for minimising risk of future disease.

The Impact of Long-Term Physical Activity Interventions for Overweight/Obese Postmenopausal Women on Adiposity Indicators, Physical Capacity, and Mental Health Outcomes: A Systematic Review

Physical activity interventions have recently become a popular strategy to help postmenopausal women prevent and manage obesity. The current systematic review evaluates the efficacy of physical activity interventions among overweight and obese postmenopausal women and sheds light on the behavioral change techniques that were employed in order to direct future research. Method. Five electronic databases were searched to identify all prospective RCT studies that examine the impact of physical activity on adiposity indicators, physical capacity, and/or mental health outcomes among healthy, sedentary overweight, and obese postmenopausal women in North America. The behavior change technique taxonomy was used to identify the various strategies applied in the programs. Results. Five RCTs met the inclusion criteria. The findings showed that adiposity indicators and physical capacity outcomes significantly improved following long-term interventions; however, mental health outcomes showed nonsignificant changes. Furthermore, 17 behavior change techniques were identified with the taxonomy across all trials. The intrapersonal-level techniques were the most common. Conclusion. Physical activity interventions had a positive effect on adiposity measures and physical capacity. Future research should focus on testing the effectiveness of physical activity interventions on mental health and incorporate strategies at the individual and environmental level to maximize the health impact on the population.

Leisure-time physical activity and intra-abdominal fat in young adulthood: A monozygotic co-twin control study

OBJECTIVE

To investigate differences in abdominal fat compartments between young adult monozygotic twin pairs discordant for leisure-time physical activity.

METHODS

Ten young adult male monozygotic twin pairs (age range 32-36 years) discordant for leisure-time physical activity during the past 3 years were systematically selected from a population-based Finnish twin cohort. Magnetic resonance image at the level of the L2-L3 intervertebral disc was used to predict intra-abdominal and subcutaneous abdominal fat masses. Dietary intake was assessed with a 4-day food diary.

RESULTS

Inactive twins had 31% more intra-abdominal fat than their active co-twins (mean difference 0.52 kg, 95% CI 0.12 to 0.91, P = 0.016), whereas the difference in subcutaneous abdominal fat was only 13% (P = 0.21) and 3% in body mass index (P = 0.28). Intraperitoneal fat mass was 41% higher among inactive twins compared to their active co-twins (mean difference 0.41 kg, 95% CI 0.11 to 0.70, P = 0.012). Dietary intake did not differ between co-twins.

CONCLUSIONS

A lower level of physical activity is related to greater accumulation of intra-abdominal fat among healthy adult males in their mid-30s. The findings highlight the importance of leisure-time physical activity independent of genes and diet in the prevention of intra-abdominal fat accumulation from early adulthood onward.

Background risk of breast cancer and the association between physical activity and mammographic density

INTRODUCTION

High physical activity has been shown to decrease the risk of breast cancer, potentially by a mechanism that also reduces mammographic density. We tested the hypothesis that the risk of developing breast cancer in the next 10 years according to the Tyrer-Cuzick prediction model influences the association between physical activity and mammographic density.

METHODS

We conducted a population-based cross-sectional study of 38,913 Swedish women aged 40-74 years. Physical activity was assessed using the validated web-questionnaire Active-Q and mammographic density was measured by the fully automated volumetric Volpara method. The 10-year risk of breast cancer was estimated using the Tyrer-Cuzick (TC) prediction model. Linear regression analyses were performed to assess the association between physical activity and volumetric mammographic density and the potential interaction with the TC breast cancer risk.

RESULTS

Overall, high physical activity was associated with lower absolute dense volume. As compared to women with the lowest total activity level (<40 metabolic equivalent hours [MET-h] per day), women with the highest total activity level (≥50 MET-h/day) had an estimated 3.4 cm(3) (95% confidence interval, 2.3-4.7) lower absolute dense volume. The inverse association was seen for any type of physical activity among women with <3.0% TC 10-year risk, but only for total and vigorous activities among women with 3.0-4.9% TC risk, and only for vigorous activity among women with ≥5.0% TC risk. The association between total activity and absolute dense volume was modified by the TC breast cancer risk (P interaction = 0.05). As anticipated, high physical activity was also associated with lower non-dense volume. No consistent association was found between physical activity and percent dense volume.

CONCLUSIONS

Our results suggest that physical activity may decrease breast cancer risk through reducing mammographic density, and that the physical activity needed to reduce mammographic density may depend on background risk of breast cancer.

Four-month course of soluble milk proteins interacts with exercise to improve muscle strength and delay fatigue in elderly participants

BACKGROUND

The benefit of protein supplementation on the adaptive response of muscle to exercise training in older people is controversial.

OBJECTIVE

To investigate the independent and combined effects of a multicomponent exercise program with and without a milk-based nutritional supplement on muscle strength and mass, lower-extremity fatigue, and metabolic markers.

DESIGN

A sample of 48 healthy sedentary men aged 60.8 ± 0.4 years were randomly assigned to a 16-week multicomponent exercise training program with a milk-based supplement containing, besides proteins [total milk proteins 4 or 10 g/day or soluble milk proteins rich in leucine (PRO) 10 g/day], carbohydrates and fat. Body composition, muscle mass and strength, and time to task failure, an index of muscle fatigue, were measured. Blood lipid, fibrinogen, creatine phosphokinase, glucose, insulin, C-reactive protein, interleukin-6, tumor necrosis factor-α soluble receptors, and endothelial markers were assessed.

RESULTS

Body fat mass was reduced after the 4-month training program in groups receiving 10 g/day of protein supplementation (P < .01). The training program sustained with the daily 10 g/day PRO was associated with a significant increase in dominant fat free mass (+5.4%, P < .01) and in appendicular muscle mass (+4.5%, P < .01). Blood cholesterol was decreased in the trained group receiving 10 g/day PRO. The index of insulin resistance (homeostasis model assessment-insulin resistance) and blood creatine phosphokinase were reduced in the groups receiving 10 g/day PRO, irrespective of exercise. The inflammatory and endothelial markers were not different between the groups. Training caused a significant improvement (+10.6% to 19.4%, P < .01) in the maximal oxygen uptake. Increased maximum voluntary contraction force was seen in the trained groups receiving 10 g/day of proteins (about 3%, P < .05). Time to task failure was improved in the trained participants receiving a 10 g/day supplementation with PRO (P < .01).

CONCLUSIONS

Soluble milk proteins rich in leucine improved time to muscle failure and increase in skeletal muscle mass and strength after prolonged multicomponent exercise training in healthy older men.

Variation in dietary intake and physical activity pattern as predictors of change in body mass index (BMI) Z-score among Brazilian adolescents

OBJECTIVE

To assess whether changes in dietary intake and physical activity pattern are associated with the annual body mass index (BMI) z-score change among adolescents.

METHODS

The study was conducted in public schools in the city of Piracicaba, Sao Paulo, Brazil, with a probabilistic sample of 431 adolescents participating in wave I (2004) (hereafter, baseline) and 299 in wave II (2005) (hereafter, follow-up). BMI, usual food intake, physical activity, screen time, sexual maturation and demographic variables were assessed twice. The association between annual change in food intake, physical activity, screen time, and annual BMI z-score changes were assessed by multiple regression.

RESULTS

The study showed a positive variation in BMI z-score over one-year. Among variables related to physical activity pattern only playing videogame and using computer increased over the year. The intake of fruits and vegetables and sugar-sweetened beverages increased over one year, while the others variables showed a reduction. An increased consumption of fatty foods (β = 0.04, p = 0.04) and sweetened natural fruit juices (β = 0.05, p = 0.03) was positively associated with the rise in BMI z-score.

CONCLUSIONS

Unhealthy dietary habits can predict the BMI z-score gain more than the physical activity pattern. The intake of fatty foods and sweetened fruit juices is associated with the BMI z-score over one year.

Top 10 research questions related to body composition

An understanding of body composition is crucial to understanding human health, disease, and function. Research in body composition has focused on the development of assessment methods, description of normal changes in body composition with growth and development and aging, and the changes that occur in body composition in response to challenges ranging from illness to planned interventions. Each focus is significant, and in a sense, they are interdependent, because technological advances allow more sophisticated questions to be addressed, which in turn drives the development of better methods. Significant advances have been made in each area, although perhaps surprisingly basic questions remain. For example, growth trajectories are often estimated from cross-sectional data, given the resources needed for long-term observational studies, and thus, longitudinal descriptive data are still needed. Along with advances in laboratory methods, development of field methods remains relevant for screening and clinical practice. Despite recognition of wide interindividual differences in intervention response, average outcomes continue to be emphasized. With technological advances, it is now possible to examine genetic along with nongenetic factors that underlie changes in body composition, and these techniques need to be applied in long-term, well-controlled trials. In this article, we review 10 key questions in related areas in which research is needed to continue to advance the field.

Triglycerides-diabetes association in healthy middle-aged men: modified by physical fitness? A long term follow-up of 1962 Norwegian men in the Oslo Ischemia Study

AIMS

To examine the impact of physical fitness (PF) on the association between fasting serum triglycerides (FTG) and diabetes risk and whether temporal changes in FTG predict diabetes risk in healthy middle-aged men.

METHODS

FTG and PF (bicycle exercise test) were measured in 1962 men aged 40-59 years in 1972-1975 (Survey 1) and repeated in 1387 still healthy men on average 7.3 years later (Survey 2). Diabetes was diagnosed according to WHO 1985-criteria.

RESULTS

During 35 years follow-up 202/1962 (10.3%) men developed diabetes. Compared with the lowest, the upper FTG tertile had a 2.58-fold (95% CI: 1.81-3.74) diabetes risk adjusted for age, fasting blood glucose and maternal diabetes, and a 2.29-fold (95%CI: 1.60-3.33) when also adjusting for PF. Compared with unchanged (±25%) FTG levels (n=664), FTG reduction of more than 25% (n=261) was associated with 56% lower (0.44; 95% CI: 0.24-0.75) diabetes risk, while FTG increase of more than 25% (n=462) was associated with similar risk. These associations were unchanged when adjusted for PF and PF change.

CONCLUSIONS

High FTG-levels predicted long-term diabetes risk in healthy middle-aged men, and the association was only modestly weakened when adjusted for PF. A reduction in FTG was associated with decreased diabetes risk.

[Bariatric surgery - significance, risks, long term consequences]

In recent years the number of bariatric surgery has markedly increased in industrial nations. Surgery provides a more rapid decrease of body weight than conservative approach. However a long term conservative follow up therapy is mandatory to stabilize reduced weight. Due to increasing knowledge from long term follow up of surgically treated obese patients there is a growing body of evidence that frequently there is necessity of reoperations and of substitution both of trace elementsand of minerals or vitamins due to their hampered enteral resorption. Additionally therapy of surgery induced endocrine alterations not seldom is necessary.These insights are of outstanding importance because meanwhile an enlargement of the indications for bariatric surgery as a therapeutic option for metabolic disorders is being discussed. This review refers to the recent internationally published papers concerning consequences of bariatric surgery.

Choose to Move for Positive Living: physical activity program for obese women

The Choose to Move for + (Positive) Living program was implemented to increase physical activity among obese women. A holistic approach was used to promote stage of health behavior change, social support, and quality of life and reduce depression. Within 6 months, physical fitness improved and depressive symptoms decreased.

Physical activity and exercise in the regulation of human adipose tissue physiology

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.

PGC-1α and exercise in the control of body weight

The increasing prevalence of obesity and its comorbidities represents a major threat to human health globally. Pharmacological treatments exist to achieve weight loss, but the subsequent weight maintenance is prone to fail in the long run. Accordingly, efficient new strategies to persistently control body weight need to be elaborated. Exercise and dietary interventions constitute classical approaches to reduce and maintain body weight, yet people suffering from metabolic diseases are often unwilling or unable to move adequately. The administration of drugs that partially mimic exercise adaptation might circumvent this problem by easing and supporting physical activity. The thermogenic peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) largely mediates the adaptive response of skeletal muscle to endurance exercise and is a potential target for such interventions. Here, we review the role of PGC-1α in mediating exercise adaptation, coordinating metabolic circuits and enhancing thermogenic capacity in skeletal muscle. We suggest a combination of elevated muscle PGC-1α and exercise as a modified approach for the efficient long-term control of body weight and the treatment of the metabolic syndrome.

Lifestyle/dietary recommendations for erectile dysfunction and female sexual dysfunction

Sexual problems are diffuse in both genders. Although epidemiologic evidence seems to support a role for lifestyle factors in erectile dysfunction, limited data are available suggesting the treatment of underlying risk factors may improve erectile dysfunction. The results are sparse regarding associations between lifestyle factors and female sexual dysfunction, and conclusions regarding influence of healthy behaviors on female sexual dysfunction cannot be made before more studies have been performed. Beyond the specific effects on sexual dysfunctions in men and women, adoption of these measures promotes a healthier life and increased well-being, which may help reduce the burden of sexual dysfunction.

Nonprescribed physical activity energy expenditure is maintained with structured exercise and implicates a compensatory increase in energy intake

BACKGROUND

Exercise interventions elicit only modest weight loss, which might reflect a compensatory reduction in nonprescribed physical activity energy expenditure (PAEE).

OBJECTIVE

The objective was to investigate whether there is a reduction in nonprescribed PAEE as a result of participation in a 6-mo structured exercise intervention in middle-aged men.

DESIGN

Sedentary male participants [age: 54 ± 5 y; body mass index (in kg/m²): 28 ± 3] were randomly assigned to a 6-mo progressive exercise (EX) or control (CON) group. Energy expenditure during structured exercise (prescribed PAEE) and nonprescribed PAEE were determined with the use of synchronized accelerometry and heart rate before the intervention, during the intervention (2, 9, and 18 wk), and within a 2-wk period of detraining after the intervention.

RESULTS

Structured prescribed exercise increased total PAEE and had no detrimental effect on nonprescribed PAEE. Indeed, there was a trend for greater nonprescribed PAEE in the EX group (P = 0.09). Weight loss in the EX group (-1.8 ± 2.2 kg compared with +0.2 ± 2.2 kg in the CON group, P < 0.02) reflected only ≈40% of the 300-373 kcal/kg body mass potential energy deficit from prescribed exercise. Serum leptin concentration decreased by 24% in the EX group (compared with 3% in the CON group, P < 0.03), and we estimate that this was accompanied by a compensatory increase in energy intake of ≈100 kcal/d.

CONCLUSIONS

The adoption of regular structured exercise in previously sedentary, middle-aged, and overweight men does not result in a negative compensatory reduction in nonprescribed physical activity. The less-than-predicted weight loss is likely to reflect a compensatory increase in energy intake in response to a perceived state of relative energy insufficiency.

Correlates of physical activity in young American Indian children: lessons learned from the Wisconsin Nutrition and Growth Study

BACKGROUND

Obesity is a serious and growing health problem in American Indian (AI) children. Our study, the Wisconsin Nutrition and Growth Study, aimed to understand the prevalence and contributing factors to pediatric obesity in Wisconsin tribes and provide the foundation for intervention design.

OBJECTIVE

This article focuses on associations among age, gender, and 3 measures of weight status with proxy-reported physical activity and TV/screen time in 3 to 8 year-old AI children.

DESIGN/METHODS

In a cross-sectional design, 581 AI children (49.1% female, aged 3-8 years) participated in health screenings that included height, weight, waist circumference, percent body fat, and a caregiver survey on demographics and health, with questions on physical activity and TV/screen time.

RESULTS

Forty-five percent of children were overweight or obese. Boys were significantly more obese and had higher levels of body fat than girls. There were no differences in weight category across age groups. Boys participated in significantly more weekly sports than girls and sports participation was somewhat higher in younger children. Body mass index and waist circumference were not significantly correlated with TV/screen time or with the 3 activity measures (sports participation, outdoor play time, or physical education classes). Hours of outdoor play significantly predicted child body fat percentage controlling for maternal body mass index and child age and gender.

CONCLUSIONS

Young AI children in Wisconsin have high rates of overweight/obesity starting at a very early age, and outdoor play may play a significant role in mediating body fat. There is a need to develop obesity-prevention interventions at early ages.

Physical activity plays an important role in body weight regulation

Emerging literature highlights the need to incorporate physical activity into every strategy intended to prevent weight gain as well as to maintain weight loss over time. Furthermore, physical activity should be part of any plan to lose weight. The stimulus of exercise provides valuable metabolic adaptations that improve energy and macronutrient balance regulation. A tight coupling between energy intake and energy expenditure has been documented at high levels of physical exercise, suggesting that exercise may improve appetite control. The regular practice of physical activity has also been reported to reduce the risk of stress-induced weight gain. A more personalized approach is recommended when planning exercise programs in a clinical weight loss setting in order to limit the compensatory changes associated to exercise-induced weight loss. With modern environment promoting overeating and sedentary behavior, there is an urgent need for a concerted action including legislative measures to promote healthy active living in order to curb the current epidemic of chronic diseases.

Post-weaning voluntary exercise exerts long-term moderation of adiposity in males but not in females in an animal model of early-onset obesity

Given the alarming increase in childhood, adolescent and adult obesity there is an imperative need for understanding the early factors affecting obesity and for treatments that may help prevent or at least moderate it. Exercise is frequently considered as an effective treatment for obesity however the empirical literature includes many conflicting findings. In the present study, we used the OLETF rat model of early-onset hyperphagia-induced obesity to examine the influence of early exercise on peripheral adiposity-related parameters in both males and females. Rats were provided voluntary access to running wheels from postnatal day (PND) 22 until PND45. We examined fat pad weight (brown, retroperitoneal, inguinal and epididymal); inguinal adipocyte size and number; and leptin, adiponectin, corticosterone and creatinine levels. We also examined body weight, feeding efficiency and spontaneous intake. Early voluntary exercise reduced intake, adiposity and leptin in the OLETF males following a sharp reduction in adipocyte size despite a significant increase in fat cell number. Exercising males from the lean LETO control strain presented stable intake, but reduced body fat, feeding efficiency and increased plasma creatinine, suggesting an increment in muscle mass. OLETF females showed reduced feeding efficiency and liver fat, and a significant increase in brown fat. Exercising LETO control females increased intake, body weight and creatinine, but no changes in body fat. Overall, OLETF rats presented higher adiponectin levels than controls in both basal and post-exercise conditions. The results suggest an effective early time frame, when OLETF males can be successfully "re-programmed" through voluntary exercise; in OLETF females the effect is much more moderate. Findings expose sex-dependent peripheral mechanisms in coping with energy challenges.

Effect of nutritional counselling and nutritional plus exercise counselling in overweight adults: a randomized trial in multidisciplinary primary care practice

OBJECTIVE

To compare the effects of nutritional counselling with nutritional plus exercise counselling on body weight and waist circumference in overweight adults in a multidisciplinary primary care setting.

METHODS

One hundred and thirty-four overweight adults (body mass index 28-35) were randomly assigned to individual counselling sessions by a dietician (D) or counselling sessions by a dietician plus physiotherapist (D + E) during 6 months with one follow-up session at 12 months. Outcomes were assessed at baseline, 6 and 12 months. Difference in changes of outcome measures between groups were analysed using generalized estimating equations.

RESULTS

Weight reduced from baseline to 6 months in D [-2.2 (-3.1 to -1.4) kg] and D + E [-3.0 (-4.0 to -2.0) kg] and was sustained at 12 months [-2.0 (-3.1 to -1.4) kg and -3.1 (-4.5 to -1.6) kg, respectively]. The reduction in weight did not significantly differ between D and D + E (P = 0.48). In both groups, waist circumference decreased from baseline to 6 months [-2.1 (-3.3 to -0.8) cm for D; -3.7 (-5.1 to -2.3) cm for D + E] and was sustained at 12 months [-2.1 (-3.5 to -0.7) cm and -4.2 (-6.0 to -2.5) cm, respectively]. Participants in D + E tended to decrease their waist circumference more than those in D (P = 0.14).

DISCUSSION

Nutritional counselling by a dietician resulted in modest reductions in weight and waist circumference in overweight adults, which were sustained up to 12 months. Adding exercise counselling by a physiotherapist did not significantly enhance the effect on body weight. Exercise counselling may, however, further improve waist circumference.

The utility of physical activity in the management of global cardiometabolic risk

Major health organizations promote the adoption of a healthy lifestyle, composed of sufficient daily physical activity and a balanced diet for the prevention and management of type 2 diabetes (T2D) and cardiovascular disease risk. In particular, it is recommended that adults accumulate 30 min of moderate-intensity aerobic physical activity on most days of the week. Despite these recommendations, a physically active lifestyle is seldom adopted, and the majority of the North American population remains sedentary. Although the optimal strategy for promoting physical activity in today's environment remains elusive, the evidence for the utility of physical activity in the management of risk factors for T2D and cardiovascular disease is overwhelming. This review examines the influence of aerobic-type physical activity on components of global cardiometabolic risk, that is, the traditional and emerging risk factors for cardiovascular disease and T2D, including visceral obesity, insulin resistance, hypertension, atherogenic dyslipidemia, thrombosis, inflammation, and cardiorespiratory fitness. Where possible, specific consideration is given to the independent effects of an acute bout of physical activity vs. chronic physical activity with weight loss vs. chronic physical activity without weight loss.

Factors that may impede the weight loss response to exercise-based interventions

The results of exercise programmes designed to reduce body fat are disappointing. However, the reporting of weight loss as mean values disguises those individuals who do lose significant amounts of fat. Why some participants produce significant exercise-induced fat loss whereas others lose little or increase fat stores is likely to be an outcome of a range of behavioural (e.g. sleep deprivation, caloric intake), inherited (e.g. muscle fibre type, gender) and physiological (e.g. hyperinsulinaemia, hypothyroidism) factors. The following review highlights possible factors involved in weight loss and discusses how individual differences may determine the extent of weight loss after an exercise intervention. Finally, implications for the treatment and prevention of obesity are discussed.

Daily physical activity and macronutrient distribution of low-calorie diets jointly affect body fat reduction in obese women

Inadequate dietary patterns and sedentary lifestyles are believed to be important factors in predisposing people to obesity. This study analyzed the potential interaction between habitual physical activity and the carbohydrate (CHO)-fat distribution in 2 hypocaloric diets and the impact of such interplay on body composition changes. Forty healthy obese women, 20–50 years old, were randomly assigned to a high- or low-CHO energy-restricted diet, which was low or high in fat, respectively, during 10 weeks. Baseline and final measurements were performed to assess dietary habits, resting metabolic rate, and body composition changes. Physical activity was measured with a triaxial accelerometer and with a questionnaire. There were no significant differences in anthropometric and metabolic variables between both dietary groups at baseline. However, there was a positive correlation between total free-living physical activity and arm muscle preservation after 10 weeks (r = 0.371; p = 0.024). Interestingly, an interaction between macronutrient (CHO–fat distribution) intake and physical activity was found, since less-active subjects with a high-CHO–low-fat diet showed a greater fat loss than those more active with a lower-CHO–high-fat diet, whereas more-active subjects with a high-CHO–low-fat diet showed a smaller fat loss than those receiving a low-CHO–high-fat diet. Physical activity and the macronutrient content of energy-restricted diets, when designed to promote body fat mass reduction, should be considered together to better predict the outcome.

Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research

Convincing evidence now supports a probable preventive role for physical activity in postmenopausal breast cancer. The mechanisms by which long-term physical activity affect risk, however, remain unclear. The aims of this review were to propose a biological model whereby long-term physical activity lowers postmenopausal breast cancer risk and to highlight gaps in the epidemiologic literature. To address the second aim, we summarized epidemiologic literature on 10 proposed biomarkers, namely, body mass index (BMI), estrogens, androgens, sex hormone binding globulin, leptin, adiponectin, markers of insulin resistance, tumor necrosis factor-alpha, interleukin-6, and C-reactive protein, in relation to postmenopausal breast cancer risk and physical activity, respectively. Associations were deemed "convincing," "probable," "possible," or "hypothesized" using set criteria. Our proposed biological model illustrated the co-occurrence of overweight/obesity, insulin resistance, and chronic inflammation influencing cancer risk through interrelated mechanisms. The most convincing epidemiologic evidence supported associations between postmenopausal breast cancer risk and BMI, estrogens, and androgens, respectively. In relation to physical activity, associations were most convincing for BMI, estrone, insulin resistance, and C-reactive protein. Only BMI and estrone were convincingly (or probably) associated with both postmenopausal breast cancer risk and physical activity. There is a need for prospective cohort studies relating the proposed biomarkers to cancer risk and for long-term exercise randomized controlled trials comparing biomarker changes over time, specifically in postmenopausal women. Future etiologic studies should consider interactions among biomarkers, whereas exercise trials should explore exercise effects independently of weight loss, different exercise prescriptions, and effects on central adiposity.

Is weight loss the optimal target for obesity-related cardiovascular disease risk reduction?

In the present review, it is argued that while weight loss is associated with substantial reduction in obesity-related cardiovascular disease risk and remains a desired outcome of relevant treatment strategies, increasing physical activity is associated with marked reduction in waist circumference, visceral fat and cardiometabolic risk factors, concurrent with an increase in cardiorespiratory fitness despite minimal or no change in body weight. Failure to recognize the benefits of exercise independent of weight loss masks opportunities to counsel and educate patients whose sole criteria for gauging obesity reduction success is the bathroom scale.