Conference on "Multidisciplinary approaches to nutritional problems". Symposium on "Diabetes and health". Challenges in the study of causation of obesity

Trapped fat: Obesity pathogenesis as an intrinsic disorder in metabolic fuel partitioning

Our understanding of the pathophysiology of obesity remains at best incomplete despite a century of research. During this time, two alternative perspectives have helped shape thinking about the etiology of the disorder. The currently prevailing view holds that excessive fat accumulation results because energy intake exceeds energy expenditure, with excessive food consumption being the primary cause of the imbalance. The other perspective attributes the initiating cause of obesity to intrinsic metabolic defects that shift fuel partitioning from pathways for mobilization and oxidation to those for synthesis and storage. The resulting reduction in fuel oxidation and trapping of energy in adipose tissue drives a compensatory increase in energy intake and, under some conditions, a decrease in expenditure. This theory of obesity pathogenesis has historically garnered relatively less attention despite its pedigree. Here, we present an updated comprehensive formulation of the fuel partitioning theory, focused on evidence gathered over the last 80 years from major animal models of obesity showing a redirection of fuel fluxes from oxidation to storage and accumulation of excess body fat with energy intake equal to or even less than that of lean animals. The aim is to inform current discussions about the etiology of obesity and by so doing, help lay new foundations for the design of more efficacious approaches to obesity research, treatment and prevention.

On the pathogenesis of obesity: causal models and missing pieces of the puzzle

Application of the physical laws of energy and mass conservation at the whole-body level is not necessarily informative about causal mechanisms of weight gain and the development of obesity. The energy balance model (EBM) and the carbohydrate-insulin model (CIM) are two plausible theories, among several others, attempting to explain why obesity develops within an overall common physiological framework of regulation of human energy metabolism. These models have been used to explain the pathogenesis of obesity in individuals as well as the dramatic increases in the prevalence of obesity worldwide over the past half century. Here, we summarize outcomes of a recent workshop in Copenhagen that brought together obesity experts from around the world to discuss causal models of obesity pathogenesis. These discussions helped to operationally define commonly used terms; delineate the structure of each model, particularly focussing on areas of overlap and divergence; challenge ideas about the importance of purported causal factors for weight gain; and brainstorm on the key scientific questions that need to be answered. We hope that more experimental research in nutrition and other related fields, and more testing of the models and their predictions will pave the way and provide more answers about the pathogenesis of obesity than those currently available.

Models of body weight and fatness regulation

Body weight and fatness appear to be regulated phenomena. Several different theoretical models are available to capture the essence of this idea. These include the set-point, dynamic equilibrium, adiposity force, control theory-settling point, Hall-Guo, operation point and dual intervention point (DIP) models. The set-point model posits a single reference point around which levels of fat are regulated. The dynamic equilibrium model suggests that the apparent regulation of body fat around a reference point is an illusion owing to the necessary impacts of weight change on energy expenditure. Control theory focuses on the importance of feedback gain and suggests set-point and dynamic equilibrium are ends of a continuum of feedback gain. Control theory models have also been called 'settling point' models. The Hall-Guo, operation point and DIP models also bring together the set-point and dynamic equilibrium ideas into a single framework. The DIP proposes a zone of indifference where dynamic equilibrium 'regulation' predominates, bounded by upper and lower intervention points beyond which physiological mechanisms are activated. The drifty gene hypothesis is an idea explaining where this individual variation in the upper intervention point might come from. We conclude that further experiments to test between the models are sorely required. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

An adiposity force induces obesity in humans independently of a normal energy balance system-a thought experiment

Obesity in humans represents a cumulative retention of a tiny fraction of total energy intake as fat, which is accompanied by growth of the metabolically active, energy-demanding, lean body mass. Since the energy balance regulation operates irrespective of the excess fat storage, availability of the required energy supplies is a permissive condition for obesity development. It occurs predominantly among people genetically predisposed and/or living with social or mental challenges. I propose a theory in which the body responds to social disruptions as threats of a future lack of food by an adiposity force building a reserve of energy independent of the regulation of the energy balance. It is based on the assumption that our evolutionary development required collaboration in gathering and sharing of food, combined with precautionary measures against anticipated failing food supplies. Social challenges are perceived as such threats, which activate the adiposity force through the brain to instigate the growth of fat and lean mass by neuro-hormonal signalling. If both perceived social threats and food abundance continue, the adiposity force pushes the fat accretion process to continue without inhibition by feedback signals from the fat mass, eventually leading to more obesity, and more so among the genetically predisposed. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

The social origins of obesity within and across generations

We propose a model for obesity development that traces a considerable part of its origins to the social domain (mainly different forms of prolonged social adversity), both within and across generations, working in tandem with a genetic predisposition. To facilitate overview of social pathways, we place particular focus on three areas that form a cascading sequence: (A) social adversity within the family (parents having a low education, a low social position, poverty and financial insecurity; offspring being exposed to gestational stress, unmet social and emotional needs, abuse, maltreatment and other negative life events, social deprivation and relationship discord); (B) increasing levels of insecurity, negative emotions, chronic stress, and a disruption of energy homeostasis; and (C) weight gain and obesity, eliciting further social stress and weight stigma in both generations. Social adversity, when combined with genetic predisposition, thereby substantially contributes to highly effective transmission of obesity from parents to offspring, as well as to obesity development within current generations. Prevention efforts may benefit from mitigating multiple types of social adversity in individuals, families, and communities, notably poverty and financial strain, and by improving education levels.

Competing paradigms of obesity pathogenesis: energy balance versus carbohydrate-insulin models

The obesity pandemic continues unabated despite a persistent public health campaign to decrease energy intake (“eat less”) and increase energy expenditure (“move more”). One explanation for this failure is that the current approach, based on the notion of energy balance, has not been adequately embraced by the public. Another possibility is that this approach rests on an erroneous paradigm. A new formulation of the energy balance model (EBM), like prior versions, considers overeating (energy intake > expenditure) the primary cause of obesity, incorporating an emphasis on “complex endocrine, metabolic, and nervous system signals” that control food intake below conscious level. This model attributes rising obesity prevalence to inexpensive, convenient, energy-dense, “ultra-processed” foods high in fat and sugar. An alternative view, the carbohydrate-insulin model (CIM), proposes that hormonal responses to highly processed carbohydrates shift energy partitioning toward deposition in adipose tissue, leaving fewer calories available for the body’s metabolic needs. Thus, increasing adiposity causes overeating to compensate for the sequestered calories. Here, we highlight robust contrasts in how the EBM and CIM view obesity pathophysiology and consider deficiencies in the EBM that impede paradigm testing and refinement. Rectifying these deficiencies should assume priority, as a constructive paradigm clash is needed to resolve long-standing scientific controversies and inform the design of new models to guide prevention and treatment. Nevertheless, public health action need not await resolution of this debate, as both models target processed carbohydrates as major drivers of obesity.

Epidemiology of Obesity

Obesity is in theory defined on the basis of the excess health risk caused by adiposity exceeding the size normally found in the population, but for practical reasons, the World Health Organization (WHO) has defined obesity as a body mass index (weight (kg)/height (m)²) of 30 or above for adults. WHO considers the steep increases in prevalence of obesity in all age groups, especially since the 1970s as a global obesity epidemic. Today, approximately 650 million adult people and approximately 340 million children and adolescence (5-19 years) suffer from obesity. It is generally more prevalent among women and older age groups than among men and younger age groups. Beyond the necessity of availability of food, evidence about causes of obesity is still very limited. However, studies have shown that obesity 'runs in families', where both genetics and environmental, and especially social, factors play important roles. Obesity is associated with an increased risk of many adverse medical, mental and social consequences, including a strong relation to type 2 diabetes. Type 2 diabetes and related metabolic syndrome and diseases are major contributors to the excess morbidity and mortality associated with obesity.

Examining Shared Pathways for Eating Disorders and Obesity in a Community Sample of Adolescents: The REAL Study

Several psychosocial models have been proposed to explain the etiology of eating disorders (EDs) and obesity separately despite research suggesting they should be conceptualized within a shared theoretical framework. The objective of the current study was to test an integrated comprehensive model consisting of a host of common risk and protective factors (socio-environmental, psychological, and behavioral) expected to explain both eating and weight disorders simultaneously in a large school-based sample of adolescents. Data were collected from 3,043 youth (60% female, 14.00 ± 1.61) from 41 schools in the Ottawa region, Canada. Working with interested school staff, validated self-report scales in the form of a questionnaire booklet were administered to participating students to assess several understood risk and protective factors common to both eating disorders and obesity. Anthropometric measurements of weight and height were taken at the end of the questionnaire administration period by trained research staff. Structural equation modeling with cross-validation was used to test the hypothesized model. Findings demonstrated that dysregulated eating was associated with both eating disorder and weight status with diet culture and emotion dysregulation directly associated with some of these disordered eating patterns. It equally pointed to how lifestyle made up of high sedentary behaviors, low vigorous exercise and varied eating patterns contributed to both emotion dysregulation and poor body image which subsequently affected eating issues and weight status simultaneously, signaling the complex interplay of psychosocial factors that underlie these concerns. This study provides evidence for an integrated psychosocial model consisting of socio-environmental, psychological, and behavioral factors may best explain the complex interplay of risk and protective factors influencing eating disorders and obesity. It equally highlights understanding the direct and indirect effects of some of the most salient risk factors involved in eating and weight-related concerns, including the strong effects of diet culture and stressors such as weight-based teasing, providing interventionalists evidence of important risk factors to consider targeting in eating disorder and weight-based prevention efforts.

Prenatal inflammation causes obesity and abnormal lipid metabolism via impaired energy expenditure in male offspring

INTRODUCTION

Obesity has becoming a global health issue. Fetus exposed to adversity in the uterine are susceptible to unhealth stimulus in adulthood. Prenatal inflammation is related to poor neonatal outcomes like neurodevelopmental impairments and respiratory complications. Recent studies suggested prenatal lipopolysaccharide (LPS) exposure could result in metabolic disorders. Thus, we hypothesized that offspring exposed to prenatal inflammation could develop into metabolic disorder.

METHODS

The pregnant C57BL/6J mice were intraperitoneally injected with 50 μg/kg LPS or saline only once at GD15. The male offspring were weighted weekly until sacrificed. Indirect calorimetry and body composition were both performed at 9 and 18 weeks old. At 20 weeks old, mice were fasted overnight before collecting blood samples and liver for metabolomics analysis and RNA sequencing, respectively. Differentially expressed genes were further verified by RT-qPCR and western blotting.

RESULTS

Prenatal inflammation resulted in obesity with increased fat percentage and decreased energy expenditure in middle-age male offspring. Abnormal lipid accumulation, changes of gene expression profile and upregulation of multi-component mechanistic target of rapamycin complex 1 (mTOR)/Peroxisome proliferator-activated receptor-γ pathway was observed in liver, accompanied with decreased bile acids level, unsaturated fatty acids androgens and prostaglandins in serum. Indirect calorimetry showed increased respiratory exchange rate and deceased spontaneous activity at 9 weeks in LPS group. Impaired energy expenditure was also observed at 18 weeks in LPS group.

CONCLUSION

Prenatal LPS exposure led to obesity and abnormal lipid metabolism through impaired energy expenditure.

Proximate, Mineral and Vitamin Analysis of Rebon Shrimp Diversification Products as an Indonesian Local Product: Supplementary Food for Malnourished Children

Background: Rebon shrimp (Acetes sp.) is a local food in the coastal areas of Southeast Asia that has good nutritional potential. It is a nutrient-rich food, high in protein, and beneficial to human health, but the utilization of rebon shrimp is still very low. Aims: This study aims to measure the proximate and mineral analysis of various rebon shrimp products that can be used as supplementary food, expected to be popularly used and consumed by the Indonesian people, particularly those of low economic income. Methods: The diversified products in this study are meatballs, floss, nuggets, fish sticks, and fish cakes made from Rebon Shrimp (Acetes sp.). The proximate levels were analyzed referring to the AOAC method, The mineral content Fe and Zn were analyzed using the AAS method. The Vitamins A and Vitamin C were determined by spectrophotometric methods and titrimetry methods. Results: This study revealed that rebon shrimp could be used in making children's healthy snacks. Snacks with rebon shrimp contributed to moisture (8.79 – 72.58 %), ash (5.06 – 10.29%), crude protein (20.41 – 27.93 %), crude fat (3.09 – 47.16%), and crude fiber (0.35 – 3.36 %). In addition, these foods also contained several important minerals and vitamins for the body, such as iron (9.47– 56.13 ppm), zinc (4.05– 40.02 ppm), Vitamin A (0.016 – 0.045%), and vitamin C (0.11 – 0.19%). Conclusion: Thus, rebon shrimp is potentially used as an alternative to local ingredients to improve the nutritional quality of children's food.

Primary prevention of fat and weight gain among obesity susceptible healthy weight preschool children. Main results from the "Healthy Start" randomized controlled intervention

BACKGROUND

A vital public health challenge lies in understanding the primary drivers behind excessive weight gain among healthy weight individuals.

OBJECTIVES

To examine if excessive weight and fat gain can be prevented among healthy weight, obesity susceptible children aged 2 to 6 years.

METHODS

Eligible children were identified based on information on either a high birth weight, maternal pre-pregnancy obesity or maternal low educational level from national registries, and randomized into an intervention group, a control group and a shadow control group. All children with overweight at baseline were excluded from subsequent analysis (n = 196), while healthy weight children were included (n = 926). The intervention was designed to deliver improvements in diet and physical activity habits, optimization of sleep quantity and quality, and reduction of family stress. The average intervention period was 1.3 years.

RESULTS

Intention-to-treat analyses indicated a lower gain in percentage fat mass and a higher gain in fat-free mass in the intervention group compared with the control group. However, the results should be interpreted with caution, as they were clinically small and borderline significant, only.

CONCLUSION

This primary prevention intervention among young healthy weight children with susceptibility to future obesity had clinically small effects on growth and body composition. More interventions, conducting primary obesity prevention, are urgently needed.

Does Proteomic Mirror Reflect Clinical Characteristics of Obesity?

Obesity is a frightening chronic disease, which has tripled since 1975. It is not expected to slow down staying one of the leading cases of preventable death and resulting in an increased clinical and economic burden. Poor lifestyle choices and excessive intake of “cheap calories” are major contributors to obesity, triggering type 2 diabetes, cardiovascular diseases, and other comorbidities. Understanding the molecular mechanisms responsible for development of obesity is essential as it might result in the introducing of anti-obesity targets and early-stage obesity biomarkers, allowing the distinction between metabolic syndromes. The complex nature of this disease, coupled with the phenomenon of metabolically healthy obesity, inspired us to perform data-centric, hypothesis-generating pilot research, aimed to find correlations between parameters of classic clinical blood tests and proteomic profiles of 104 lean and obese subjects. As the result, we assembled patterns of proteins, which presence or absence allows predicting the weight of the patient fairly well. We believe that such proteomic patterns with high prediction power should facilitate the translation of potential candidates into biomarkers of clinical use for early-stage stratification of obesity therapy.

Road traffic noise and markers of adiposity in the Danish Nurse Cohort: A cross-sectional study

BACKGROUND

Studies have suggested that traffic noise is associated with markers of obesity. We investigated the association of exposure to road traffic noise with body mass index (BMI) and waist circumference in the Danish Nurse Cohort.

METHODS

We used data on 15,501 female nurses (aged >44 years) from the nationwide Danish Nurse Cohort who, in 1999, reported information on self-measured height, weight, and waist circumference, together with information on socioeconomic status, lifestyle, work and health. Road traffic noise at the most exposed façade of the residence was estimated using Nord2000 as the annual mean of a weighted 24-h average (L_den). We used multiple linear regression models to examine associations of road traffic noise levels in 1999 (1-year mean) with BMI and waist circumference, adjusting for potential confounders, and evaluated effect modification by degree of urbanization, air pollution levels, night shift work, job strain, sedative use, sleep aid use, and family history of obesity.

RESULTS

We did not observe associations between road traffic noise (per 10 dB increase in the 1-year mean L_den) and BMI (kg/m²) (β: 0.00; 95% confidence interval (CI): -0.07, 0.07) or waist circumference (cm) (β: -0.09; 95% CI: -0.31, 0.31) in the fully adjusted model. We found significant effect modification of job strain and degree of urbanization on the associations between L_den and both BMI and waist circumference. Job strained nurses were associated with a 0.41 BMI-point increase, (95% CI: 0.06, 0.76) and a 1.00 cm increase in waist circumference (95% CI: 0.00, 2.00). Nurses living in urban areas had a statistically significant positive association of L_den with BMI (β: 0.26; 95% CI: 0.11, 0.42), whilst no association was found for nurses living in suburban and rural areas.

CONCLUSION

Our results suggest that road traffic noise exposure in nurses with particular susceptibilities, such as those with job strain, or living in urban areas, may lead to increased BMI, a marker of adiposity.

Adiposity, breast density, and breast cancer risk: epidemiological and biological considerations

Excess total body fat and abdominal adipose tissue are recognized risk factors for metabolic diseases but also for some types of cancers, including breast cancer. Several biological mechanisms in connection with local and systemic effects of adiposity are believed to be implicated in breast cancer development, and may involve breast fat. Breast adipose tissue can be studied through mammography by looking at breast density features such as the nondense area mainly composed of fat, or the percent breast density, which is the proportion of fibroglandular tissue in relation to fat. The relation between adiposity, breast density features, and breast cancer is complex. Studies suggest a paradoxical association as adiposity and absolute nondense area correlate positively with each other, but in contrast to adiposity, absolute nondense area seems to be associated negatively with breast cancer risk. As breast density is one of the strongest risk factors for breast cancer, it is therefore critical to understand how these factors interrelate. In this review, we discuss these relations by first presenting how adiposity measurements and breast density features are linked to breast cancer risk. Then, we used a systematic approach to capture the literature to review the relation between adiposity and breast density features. Finally, the role of adipose tissue in carcinogenesis is discussed briefly from a biological perspective.

Gene-nutrient interactions and susceptibility to human obesity

A large number of genome-wide association studies, transferability studies, and candidate gene studies performed in diverse populations around the world have identified gene variants that are associated with common human obesity. The mounting evidence suggests that these obesity gene variants interact with multiple environmental factors and increase susceptibility to this complex metabolic disease. The objective of this review article is to provide concise and updated information on energy balance, heritability of body weight, origins of gene variants, and gene-nutrient interactions in relation to human obesity. It is proposed that knowledge of these related topics will provide valuable insight for future preventative lifestyle intervention using targeted nutritional and medicinal therapies.

Dietary Intake at 9 Years and Subsequent Body Mass Index in Adolescent Boys and Girls: A Study of Monozygotic Twin Pairs

There is a lack of evidence pointing to specific dietary elements related to weight gain and obesity prevention in childhood and adulthood. Dietary intake and obesity are both inherited and culturally transmitted, but most prospective studies on the association between diet and weight status do not take genetics into consideration. The objective of this study was to document the association between dietary intake at 9 years and subsequent Body Mass Index (BMI) in adolescent monozygotic boy and girl twin pairs. This research used data from 152 twin pairs. Dietary data were collected from two 24-hour-recall interviews with a parent and the child aged 9 years. Height and weight were obtained when the twins were aged 9, 12, 13, and 14 years. Intrapair variability analysis was performed to identify dietary elements related to BMI changes in subsequent years. BMI-discordant monozygotic twin pairs were also identified to analyze the dietary constituents that may have generated the discordance. After eliminating potential confounding genetic factors, pre-adolescent boys who ate fewer grain products and fruit and consumed more high-fat meat and milk had higher BMIs during adolescence; pre-adolescent girls who consumed more grain products and high-fat meat and milk had higher BMIs during adolescence. Energy intake (EI) at 9 years was not related to BMI in subsequent years. Our study suggests that messages and interventions directed at obesity prevention could take advantage of sex-specific designs and' eventually' genetic information.

Long-term exposure to residential traffic noise and changes in body weight and waist circumference: A cohort study

BACKGROUND

Traffic noise can act as a stressor and disturb sleep, and has been associated with cardiovascular disease. Recent studies suggest a possible association to metabolic outcomes and adiposity through biological mechanisms related to physiological stress and sleep disturbance.

OBJECTIVES

We aimed to investigate the association between long-term residential traffic noise and changes in adiposity.

MATERIALS AND METHODS

The study was based on 39,720 middle-aged Danish men and women from a cohort, with information on weight and waist circumference at two points in time. Residential exposure to traffic noise was calculated for all participants' present and historical addresses using the Nordic prediction method. The associations between traffic noise and changes in adiposity measures after a mean follow-up of 5.3 years were analyzed by linear and logistic regression with adjustments for age, sex, socioeconomic position and lifestyle factors in three models with increasing adjustment.

RESULTS

In linear models adjusted for sex, age, socioeconomic position and competing noise sources we found road traffic noise to be significantly associated with small gains in both weight and waist circumference. For example, time-weighted mean exposure 5-years preceding follow-up was associated with a yearly weight gain of 15.4 g (95% confidence interval (CI): 2.14; 28.7) and a yearly increase in waist circumference of 0.22 mm (95% CI: 0.018; 0.43) per 10dB. Similarly, in Poisson regression models we found an 10% increased risk for gaining more than 5 kg body weight during follow-up (95% CI: 1.04; 1.15) per 10 dB higher 5 years exposure preceding follow-up. Exposure to railway noise above 55 dB was associated with weight gain (39.9 g/year (95% CI: 10.2; 69.6)), but not with a significant change in waist circumference. We found baseline BMI (p<0.001) and waist circumference (p=0.001) to be significant effect modifiers for the association between road traffic noise and waist circumference, with gain in waist circumference only among the obese (BMI≥30) participants (1.20 mm/year (95% CI: 0.68; 1.72)) and participants with a large waist circumference (0.83 mm/year (95% CI: 0.42; 1.23)).

CONCLUSION

The findings supports previous studies suggesting that traffic noise may be associated with development of adiposity. However, the potential effects are small and suggest an effect mainly among obese participants.

The Association between Newborn Regional Body Composition and Cord Blood Concentrations of C-Peptide and Insulin-Like Growth Factor I

Background

Third trimester fetal growth is partially regulated by C-peptide and insulin-like growth factor I (IGF-I). Prenatal exposures including maternal obesity and high gestational weight gain as well as high birth weight have been linked to subsequent metabolic disease. We evaluated the associations between newborn regional body composition and cord blood levels of C-peptide and IGF-I.

Methods

We prospectively included obese and normal-weight mothers and their newborns; cord blood was collected and frozen. Analyses of C-peptide and IGF-I were performed simultaneously, after recruitment was completed. Newborn regional body composition was assessed with dual-energy X-ray absorptiometry scanning (DXA) within 48 hours of birth.

Results

Three hundred thirty-six term infants were eligible to participate in the study; of whom 174 (52%) infants had cord blood taken. Total, abdominal and arm and leg fat mass were positively associated with C-peptide (p < 0.001). Arm and leg fat mass was associated with IGF-I concentration: 28 g [95% confidence interval: 4, 53] per doubling of IGF-I. There was no association between total or abdominal fat mass and IGF-I. Fat-free mass was positively associated with both C-peptide (p < 0.001) and IGF-I (p = 0.004).

Conclusion

Peripheral fat tissue accumulation was associated with cord blood C-peptide and IGF-I. Total and abdominal fat masses were related to C-peptide but not to IGF-I. Thus, newborn adiposity is partially mediated through C-peptide and early linear growth is associated with IGF-I.

Maternal salivary cortisol levels during pregnancy are positively associated with overweight children

INTRODUCTION

Animal and human studies suggest that programing of the hypothalamic-pituitary-adrenal (HPA) axis may be involved in the development of obesity, but human studies of biological indicators of HPA axis activity are lacking. We studied the association between levels of the stress hormone cortisol during pregnancy and overweight offspring during childhood into adolescence.

METHODS

Salivary samples from 655 Danish pregnant women with singleton pregnancies (1989-1991) were collected once in the morning and once in the evening in their second and third trimester. We followed the offspring from two to 16 years of age with at least one measurement of height and weight, and classified their body mass index into overweight and normal weight. The adjusted relative difference in median salivary cortisol (with 95% confidence interval (CI)) during pregnancy (the four samples), in second and third trimester (morning and evening samples) between overweight and normal weight offspring was estimated. Furthermore, the adjusted median ratio between morning and evening maternal salivary cortisol level was estimated for normal weight and overweight children. All the analyses were stratified into the equal age groups: 2-6, 7-11, and 12-16 years.

RESULTS

We found non-significant higher maternal cortisol levels during pregnancy in offspring that were overweight at the age of 2-6, 7-11 and 12-16 years than in normal weight peers; adjusted relative difference in median salivary cortisol 11% (95% CI: -2; 25), 6% (95% CI: -7; 20), and 9% (95% CI: -4; 24), respectively. A statistically significantly higher level of maternal cortisol was found in the second trimester in 2-6-year-old and 12-16-year-old overweight offspring; relative difference 19% (95% CI: 3; 37), and 20% (95% CI: 3; 41), respectively. The median ratio between morning and evening maternal salivary cortisol level was similar for overweight and normal weight children; e.g. at age 2-6 years in third trimester 4.31 (95% CI: 4.05; 4.60)nmol/l and 4.28 (95% CI: 3.60; 5.09)nmol/l, respectively (P=0.93).

CONCLUSION

Our findings suggest a relatively consistent association between pregnancy cortisol levels and overweight offspring, especially in the second trimester.

Childhood Obesity Is a Chronic Disease Demanding Specific Health Care--a Position Statement from the Childhood Obesity Task Force (COTF) of the European Association for the Study of Obesity (EASO)

Childhood obesity is one of the greatest health challenges of the 21st century. The EASO COTF is convinced that classifying obesity as a chronic disease in children and adolescents is a crucial step for increasing individual and societal awareness, and for improving early diagnosis and intervention. Such a classification will enhance the development of novel preventive and treatment approaches, health care policies and systems, and the education of healthcare workers. The management of obesity prior to the appearance of co-morbidities may prevent their escalation into significant medical and psychosocial problems, and reduce their economic and societal impact. Childhood is a unique window of opportunity to influence lifetime effects on health, quality of life, prevention of non-communicable chronic diseases and disabilities. The Convention on the Rights of the Child by UNICEF states that parties shall strive to ensure that no child is deprived of his or her right of access to health care services. The EASO COTF is aiming to address these issues via educational activities for health care workers, identification of research agendas, and the promotion of collaborations among clinicians, researchers, health institutions, organizations and states across Europe.

The pathophysiology of hypertension in patients with obesity

The combination of obesity and hypertension is associated with high morbidity and mortality because it leads to cardiovascular and kidney disease. Potential mechanisms linking obesity to hypertension include dietary factors, metabolic, endothelial and vascular dysfunction, neuroendocrine imbalances, sodium retention, glomerular hyperfiltration, proteinuria, and maladaptive immune and inflammatory responses. Visceral adipose tissue also becomes resistant to insulin and leptin and is the site of altered secretion of molecules and hormones such as adiponectin, leptin, resistin, TNF and IL-6, which exacerbate obesity-associated cardiovascular disease. Accumulating evidence also suggests that the gut microbiome is important for modulating these mechanisms. Uric acid and altered incretin or dipeptidyl peptidase 4 activity further contribute to the development of hypertension in obesity. The pathophysiology of obesity-related hypertension is especially relevant to premenopausal women with obesity and type 2 diabetes mellitus who are at high risk of developing arterial stiffness and endothelial dysfunction. In this Review we discuss the relationship between obesity and hypertension with special emphasis on potential mechanisms and therapeutic targeting that might be used in a clinical setting.

Energy gap in the aetiology of body weight gain and obesity: a challenging concept with a complex evaluation and pitfalls

The concept of energy gap(s) is useful for understanding the consequence of a small daily, weekly, or monthly positive energy balance and the inconspicuous shift in weight gain ultimately leading to overweight and obesity. Energy gap is a dynamic concept: an initial positive energy gap incurred via an increase in energy intake (or a decrease in physical activity) is not constant, may fade out with time if the initial conditions are maintained, and depends on the 'efficiency' with which the readjustment of the energy imbalance gap occurs with time. The metabolic response to an energy imbalance gap and the magnitude of the energy gap(s) can be estimated by at least two methods, i.e. i) assessment by longitudinal overfeeding studies, imposing (by design) an initial positive energy imbalance gap; ii) retrospective assessment based on epidemiological surveys, whereby the accumulated endogenous energy storage per unit of time is calculated from the change in body weight and body composition. In order to illustrate the difficulty of accurately assessing an energy gap we have used, as an illustrative example, a recent epidemiological study which tracked changes in total energy intake (estimated by gross food availability) and body weight over 3 decades in the US, combined with total energy expenditure prediction from body weight using doubly labelled water data. At the population level, the study attempted to assess the cause of the energy gap purported to be entirely due to increased food intake. Based on an estimate of change in energy intake judged to be more reliable (i.e. in the same study population) and together with calculations of simple energetic indices, our analysis suggests that conclusions about the fundamental causes of obesity development in a population (excess intake vs. low physical activity or both) is clouded by a high level of uncertainty.

Harnessing the beneficial properties of adipogenic microbes for improving human health

Obesity is associated with numerous metabolic comorbidities. Weight loss is an effective measure for alleviating many of these metabolic abnormalities. However, considering the limited success of most medical weight-management approaches in producing a sustained weight loss, approaches that improve obesity-related metabolic abnormalities independent of weight loss would be extremely attractive and of practical benefit. Metabolically healthy obesity supports the notion that a better metabolic profile is possible despite obesity. Moreover, adequate expansion of adipose tissue appears to confer protection from obesity-induced metabolic comorbidities. To this end, the 10th Stock conference examined new approaches to improve metabolic comorbidities independent of weight loss. In particular, human adenovirus 36 (Ad36) and specific gut microbes were examined for their potential to influence lipid and glucose homeostasis in animals and humans. While these microbes possess some undesirable properties, research has identified attributes of adenovirus Ad36 and gut microbes that may be selectively harnessed to improve metabolic profile without the obligatory weight loss. Furthermore, identifying the host signalling pathways that these microbes recruit to improve the metabolic profile may offer new templates and targets, which may facilitate the development of novel treatment strategies for obesity-related metabolic conditions.

The Importance of Energy Balance

Globally, bodyweight and obesity are rising in both the developing and developed world. To maintain a stable bodyweight, energy intake must, over time, exactly equal energy expenditure, a state known as energy balance. An understanding of the physiologic control of energy balance may be useful for designing interventions to tackle the obesity epidemic worldwide. Obesity occurs when the body's energy balance is positive (i.e. when energy intake exceeds energy expenditure). Human physiology is biased towards maintaining energy balance at high levels of energy intake and expenditure. As a result, strategies to combat obesity should include a focus on increasing physical activity along with strategies for modifying food intake. An understanding of energy balance leads to the conclusion that prevention of weight gain should be easier than treatment of obesity. Components of energy balance are interdependent, and weight loss requires major behaviour changes, which trigger compensatory decreases in energy expenditure that facilitate weight regain. Prevention of weight gain can be accomplished by smaller behaviour changes. In addition to being easier to sustain than larger behaviour changes, smaller ones produce less compensation by the energy balance regulatory system. It has been estimated that relatively small changes in energy intake and expenditure totaling 100 kcal per day could arrest weight gain in most people. Interventions that advocate small changes have shown promising levels of success.

Childhood intelligence and adult obesity

OBJECTIVE

Recent studies conclude childhood intelligence has no direct effect on adult obesity net of education, but evolutionary psychological theories suggest otherwise.

DESIGN AND METHODS

A population (n = 17,419) of British babies has been followed since birth in 1958 in a prospectively longitudinal study. Childhood general intelligence is measured at 7, 11, and 16, and adult BMI and obesity are measured at 51.

RESULTS

Childhood general intelligence has a direct effect on adult BMI, obesity, and weight gain, net of education, earnings, mother's BMI, father's BMI, childhood social class, and sex. More intelligent children grow up to eat more healthy foods and exercise more frequently as adults.

CONCLUSION

Childhood intelligence has a direct effect on adult obesity unmediated by education or earnings. General intelligence decreases BMI only in adulthood when individuals have complete control over what they eat.

Tackling overweight and obesity: does the public health message match the science?

BACKGROUND

Despite the increasing understanding of the mechanisms relating to weight loss and maintenance, there are currently no validated public health interventions that are able to achieve sustained long-term weight loss or to stem the increasing prevalence of obesity in the population. We aimed to examine the models of energy balance underpinning current research about weight-loss intervention from the field of public health, and to determine whether they are consistent with the model provided by basic science. EMBASE was searched for papers published in 2011 on weight-loss interventions. We extracted details of the population, nature of the intervention, and key findings for 27 articles.

DISCUSSION

Most public health interventions identified were based on a simple model of energy balance, and thus attempted to reduce caloric consumption and/or increase physical activity in order to create a negative energy balance. There appeared to be little consideration of homeostatic feedback mechanisms and their effect on weight-loss success. It seems that there has been a lack of translation between recent advances in understanding of the basic science behind weight loss, and the concepts underpinning the increasingly urgent efforts to reduce excess weight in the population.

SUMMARY

Public health weight-loss interventions seem to be based on an outdated understanding of the science. Their continued failure to achieve any meaningful, long-term results reflects the need to develop intervention science that is integrated with knowledge from basic science. Instead of asking why people persist in eating too much and exercising too little, the key questions of obesity research should address those factors (environmental, behavioral or otherwise) that lead to dysregulation of the homeostatic mechanism of energy regulation. There is a need for a multidisciplinary approach in the design of future weight-loss interventions in order to improve long-term weight-loss success.

Contributions of incidence and persistence to the prevalence of childhood obesity during the emerging epidemic in Denmark

Background

Prevalence of obesity is the result of preceding incidence of newly developed obesity and persistence of obesity. We investigated whether increasing incidence and/or persistence during childhood drove the prevalence of childhood obesity during the emerging epidemic.

Methods

Height and weight were measured at ages 7 and 13 years in 192,992 Danish school children born 1930–1969. Trends in the incidence (proportion obese at 13 years among those not obese at 7 years) and persistence (proportion obese at 13 years among those obese at 7 years) across birth cohort periods (1930–41 with low stable prevalence of obesity, 1942–51 with increasing prevalence, 1952–69 with the higher, but stable prevalence) were investigated. Logistic regression was used to examine the associations between BMI at 7 years as a continuous trait, allowing interactions with the birth cohorts, and occurrence of obesity at 13 years.

Results

The prevalence of obesity was similar at 7 and 13 years and increased across birth cohorts in boys from around 0.1% to 0.5% and in girls from around 0.3% to 0.7%. The incidence of obesity between ages 7 and 13 years increased from 0.15% to 0.35% in boys and from 0.20% to 0.44% in girls. The persistence increased from 28.6% to 41.4% in boys and from 16.4% to 31.0% in girls. Despite a decrease over time, the remission of obesity occurred in >60% of obese children in the last birth cohort. However, the odds ratios of obesity at age 13 years in relation to the full range of BMI at 7 years remained unchanged across the birth cohort periods.

Conclusions/Significance

The development of the obesity epidemic in children was due to an increase in both incidence and persistence of obesity. Contrary to prevailing expectations, a large, although declining, proportion of children obese at an early age underwent remission during childhood.

Predisposition to Obesity: Should We Target Those Most Susceptible?

Obesity prevention should remain a priority, even if there is some suggestion that the epidemic may presently have reached a stable level. However, previous interventions have not been effective in preventing overweight and obesity, and at the same time studies suggest that some subgroups are more predisposed to future obesity. The purpose of this paper is to review interventions on obesity prevention published during the past year, and to examine if interventions targeting predisposed groups or individuals seem more efficient in preventing obesity than studies targeting general populations. Among 15 identified studies, 7 targeted predisposed children or adolescents. More of the studies targeting predisposed individuals were able to show significant effects than the studies targeting general populations. Most studies targeting predisposed defined the predisposition based on ethnicity or socioeconomic status. Thus, we may be more successful in preventing obesity when targeting predisposed individuals, but more studies are needed before a firm conclusion can be drawn.

Bariatric surgery, adipose tissue and gut microbiota

Human obesity can be viewed as a set of phenotypes that evolve over time in a sequence of stages that need to be precisely measured. Environmental, behavioral, genetic and biological factors interact to cause obesity. This presentation provides a clinical viewpoint on some biological processes that may explain some of the stages in the development of human obesity, its chronic maintenance and occurrence of complications, with a focus on brain structures, genetics, the profound alterations in adipose tissue biology and gut microbiota components. Roux-en-Y gastric bypass surgery is an increasingly effective model to study in this context because it leads to major improvements in glucose and lipid homeostasis and to the amelioration of some systemic inflammatory markers.

Sleep and metabolic function

Evidence for the role of sleep on metabolic and endocrine function has been reported more than four decades ago. In the past 30 years, the prevalence of obesity and diabetes has greatly increased in industrialized countries, and self-imposed sleep curtailment, now very common, is starting to be recognized as a contributing factor, alongside with increased caloric intake and decreased physical activity. Furthermore, obstructive sleep apnea, a chronic condition characterized by recurrent upper airway obstruction leading to intermittent hypoxemia and sleep fragmentation, has also become highly prevalent as a consequence of the epidemic of obesity and has been shown to contribute, in a vicious circle, to the metabolic disturbances observed in obese patients. In this article, we summarize the current data supporting the role of sleep in the regulation of glucose homeostasis and the hormones involved in the regulation of appetite. We also review the results of the epidemiologic and laboratory studies that investigated the impact of sleep duration and quality on the risk of developing diabetes and obesity, as well as the mechanisms underlying this increased risk. Finally, we discuss how obstructive sleep apnea affects glucose metabolism and the beneficial impact of its treatment, the continuous positive airway pressure. In conclusion, the data available in the literature highlight the importance of getting enough good sleep for metabolic health.

Circulating levels of persistent organic pollutants associate in divergent ways to fat mass measured by DXA in humans

BACKGROUND

Environmental contaminants have recently been implicated in the pathogenesis of obesity.

OBJECTIVE

To explore relations between persistent organic pollutants (POPs) and fat mass independently of body stature, using a cross-sectional design.

METHODS

In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS), fat mass was determined in 70-year-old subjects (n=890) by dual-energy X-ray absorptiometry (DXA). The plasma levels of 21 POPs (including 16 PCB congeners, 3 OC pesticides, 1 BDE47, and 1 dioxin) were measured by high resolution chromatography coupled with high resolution mass spectrometry (HRGC/HRMS).

RESULTS

Lipid-standardized plasma concentrations of octachlorodibenzo-p-dioxin (OCDD), the PCBs 74, 99, 105 and 118, and the pesticides HCB, TNK, and DDE were all positively related to fat mass (p=0.03-0.0001). Subjects in the fifth quintile for PCB 105 showed a mean fat mass that was 4.8 kg more than subjects in the first quintile. On the other hand, the PCBs 156, 157, 169, 170, 180, 189, 194, 206, and 209 were negatively related to fat mass (p=0.0001). For PCB 194, subjects in the fifth quintile showed a mean fat mass that was 10.8 kg less than subjects in the first quintile. Following adjustment for smoking, physical activity, education level, height, lean mass, and gender, these results remained significant (p=0.01-0.0001) except for the PCBs 74 and 99. For some PCBs, the associations vs. fat mass were more pronounced in women than in men.

CONCLUSION

Plasma concentrations of some pesticides are positively related to fat mass, while divergent associations are seen for the PCBs. These results implicate a complex role of POPs in obesity.

Obesity research based on the Copenhagen School Health Records Register

INTRODUCTION

To summarise key findings from research performed using data from the Copenhagen School Health Records Register over the last 30 years with a main focus on obesity-related research. The register contains computerised anthropometric information on 372,636 schoolchildren from the capital city of Denmark. Additional information on the cohort members has been obtained via linkages with population studies and national registers.

RESEARCH TOPICS

Studies using data from the register have made important contributions in the areas of the aetiology of obesity, the development of the obesity epidemic, and the long-term health consequences of birth weight as well as body size and growth in childhood.

CONCLUSION

Research using this unique register is ongoing, and its contributions to the study of obesity as well as other topics will continue for years to come.

Simulation models of obesity: a review of the literature and implications for research and policy

Simulation models (SMs) combine information from a variety of sources to provide a useful tool for examining how the effects of obesity unfold over time and impact population health. SMs can aid in the understanding of the complex interaction of the drivers of diet and activity and their relation to health outcomes. As emphasized in a recently released report of the Institute or Medicine, SMs can be especially useful for considering the potential impact of an array of policies that will be required to tackle the obesity problem. The purpose of this paper is to present an overview of existing SMs for obesity. First, a background section introduces the different types of models, explains how models are constructed, shows the utility of SMs and discusses their strengths and weaknesses. Using these typologies, we then briefly review extant obesity SMs. We categorize these models according to their focus: health and economic outcomes, trends in obesity as a function of past trends, physiologically based behavioural models, environmental contributors to obesity and policy interventions. Finally, we suggest directions for future research.

Short sleep duration as a possible cause of obesity: critical analysis of the epidemiological evidence

Systematic literature search for epidemiological evidence for an association of short sleep with weight gain and eventual development of obesity provided 71 original studies and seven reviews of various subsets of these studies. We have summarized the evidence for such an association with particular emphasis on prospective studies. The studies showed that short sleep duration is consistently associated with development of obesity in children and young adults, but not consistently so in older adults. We have identified critical aspects of the evidence, and assessed the possibility for interpretation of the evidence in terms of causality. We have discussed the requirement of temporal sequence between putative exposure and outcome and the implications of the time lag between them, the problems in adequate measurements of exposure and effects, the possible bidirectional causal effects, the necessary distinction between confounders and mediators, the possible confounding by weight history, and the possibility of common or upstream underlying causes. In conclusion, causal interpretation of the association is hampered by fundamental conceptual and methodological problems. Experimental studies may elucidate mechanisms, but adequate coverage of the entire pathway from sleep curtailment through obesity development is not feasible. Randomized trials are needed to assess the value of targeted interventions.

The levelling off of the obesity epidemic since the year 1999--a review of evidence and perspectives

The purpose was to investigate a possible levelling off in the obesity epidemic, by systematically reviewing literature and web-based sources. Eligible studies and data sources were required to have at least two measures of obesity prevalence since 1999. A literature and Internet search resulted in 52 studies from 25 different countries. The findings supported an overall levelling off of the epidemic in children and adolescents from Australia, Europe, Japan and the USA. In adults, stability was found in the USA, while increases were still observed in some European and Asian countries. Some evidence for heterogeneity in the obesity trends across socioeconomic status (SES) groups was found. The levelling off was less evident in the lower-SES groups. No obvious differences between genders were identified. We discussed potential explanations for a levelling off and the utility of investigating obesity trends to identify the driving forces behind the epidemic. It is important to emphasize that the levelling off is not tantamount to calling off the epidemic. Additionally, it is worthwhile to keep in mind that previous stable phases have been followed by further increases in the prevalence of obesity. Therefore, research into the causes, prevention and treatment of obesity should remain a priority.

Mediterranean dietary patterns and prospective weight change in participants of the EPIC-PANACEA project

BACKGROUND

There is an association between a greater adherence to a Mediterranean diet and a reduced risk of developing chronic diseases. However, it is not clear whether this dietary pattern may be protective also against the development of obesity.

OBJECTIVE

We assessed the association between the adherence to the Mediterranean dietary pattern (MDP), prospective weight change, and the incidence of overweight or obesity.

DESIGN

We conducted a prospective cohort study [the European Prospective Investigation into Cancer and Nutrition-Physical Activity, Nutrition, Alcohol Consumption, Cessation of Smoking, Eating Out of Home, and Obesity (EPIC-PANACEA) project] in 373,803 individuals (103,455 men and 270,348 women; age range: 25-70 y) from 10 European countries. Anthropometric measurements were obtained at recruitment and after a median follow-up time of 5 y. The relative Mediterranean Diet Score (rMED; score range: 0-18) was used to assess adherence to the MDP according to the consumption of 9 dietary components that are characteristic of the Mediterranean diet. The association between the rMED and 5-y weight change was modeled through multiadjusted mixed-effects linear regression.

RESULTS

Individuals with a high adherence to the MDP according to the rMED (11-18 points) showed a 5-y weight change of -0.16 kg (95% CI: -0.24, -0.07 kg) and were 10% (95% CI: 4%, 18%) less likely to develop overweight or obesity than were individuals with a low adherence to the MDP (0-6 points). The low meat content of the Mediterranean diet seemed to account for most of its positive effect against weight gain.

CONCLUSION

This study shows that promoting the MDP as a model of healthy eating may help to prevent weight gain and the development of obesity.

Prenatal stress exposure related to maternal bereavement and risk of childhood overweight

BACKGROUND

It has been suggested that prenatal stress contributes to the risk of obesity later in life. In a population-based cohort study, we examined whether prenatal stress related to maternal bereavement during pregnancy was associated with the risk of overweight in offspring during school age.

METHODOLOGY/PRINCIPAL FINDINGS

We followed 65,212 children born in Denmark from 1970-1989 who underwent health examinations from 7 to 13 years of age in public or private schools in Copenhagen. We identified 459 children as exposed to prenatal stress, defined by being born to mothers who were bereaved by death of a close family member from one year before pregnancy until birth of the child. We compared the prevalence of overweight between the exposed and the unexposed. Body mass index (BMI) values and prevalence of overweight were higher in the exposed children, but not significantly so until from 10 years of age and onwards, as compared with the unexposed children. For example, the adjusted odds ratio (OR) for overweight was 1.68 (95% confidence interval [CI] 1.08-2.61) at 12 years of age and 1.63 (95% CI 1.00-2.61) at 13 years of age. The highest ORs were observed when the death occurred in the period from 6 to 0 month before pregnancy (OR 3.31, 95% CI 1.71-6.42 at age 12, and OR 2.31, 95% CI 1.08-4.97 at age 13).

CONCLUSIONS/SIGNIFICANCE

Our results suggest that severe pre-pregnancy stress is associated with an increased risk of overweight in the offspring in later childhood.

Validity of claims made in weight management research: a narrative review of dietetic articles

BACKGROUND

The best available evidence demonstrates that conventional weight management has a high long-term failure rate. The ethical implications of continued reliance on an energy deficit approach to weight management are under-explored.

METHODS

A narrative literature review of journal articles in The Journal of Human Nutrition and Dietetics from 2004 to 2008.

RESULTS

Although the energy deficit approach to weight management has a high long-term failure rate it continues to dominate research in the field. In the current research agenda, controversies and complexities in the evidence base are inadequately discussed, and claims about the likely success of weight management misrepresent available evidence.

CONCLUSIONS

Dietetic literature on weight management fails to meet the standards of evidence based medicine. Research in the field is characterised by speculative claims that fail to accurately represent the available data. There is a corresponding lack of debate on the ethical implications of continuing to promote ineffective treatment regimes and little research into alternative non-weight centred approaches. An alternative health at every size approach is recommended.

Maternal postpartum distress and childhood overweight

OBJECTIVE

We investigated associations between maternal postpartum distress covering anxiety, depression and stress and childhood overweight.

METHODS

We performed a prospective cohort study, including 21,121 mother-child-dyads from the Danish National Birth Cohort (DNBC). Maternal distress was measured 6 months postpartum by 9 items covering anxiety, depression and stress. Outcome was childhood overweight at 7-years-of age. Multiple logistic regression analyses were performed and information on maternal age, socioeconomic status, pre-pregnancy BMI, gestational weight gain, parity, smoking during pregnancy, paternal BMI, birth weight, gestational age at birth, sex, breastfeeding and finally infant weight at 5 and 12 month were included in the analyses.

RESULTS

We found, that postpartum distress was not associated with childhood risk of overweight, OR 1.00, 95%CI [0.98-1.02]. Neither was anxiety, depression, or stress exposure, separately. There were no significant differences between the genders. Adjustment for potential confounders did not alter the results.

CONCLUSION

Maternal postpartum distress is apparently not an independent risk factor for childhood overweight at 7-years-of-age. However, we can confirm previous findings of perinatal determinants as high maternal pre-pregnancy BMI, and smoking during pregnancy being risk factors for childhood overweight.

Bariatric surgery: a cost-effective intervention for morbid obesity; functional and nutritional outcomes

Obesity has been described as the health crisis of the 21st century. It is a chronic lifelong medical condition, whose pattern often starts in childhood, and is demographically worsening in every developed country. The cost of treating the many medical conditions associated with obesity threatens to overwhelm healthcare resources. Medical treatments produce at most no more than 10% weight loss in the severely obese, with high failure rates. In this article, we review the available evidence regarding long-term reduction in weight, reduced mortality and improvement in most, if not all, obesity-related comorbidities. There is a need for daily multivitamins and extra minerals, especially with gastric bypass, and nutritional deficiencies of vitamins D and B12, Ca, Fe and folate need monitoring and prevention. Currently there is no medical therapy on the near horizon that will match the effect of surgery, which, if done safely, remains the only effective therapy. Bariatric surgery is cost effective, and health providers should embrace the development and rapid expansion of services.