A role for suppressed skeletal muscle thermogenesis in pathways from weight fluctuations to the insulin resistance syndrome

The association between growth patterns and blood pressure in children and adolescents: A cross-sectional study of seven provinces in China

Aimed to investigate the associations between different growth patterns with high blood pressure, and further examine the mediation effect of BMI between growth patterns and high blood pressure among children and adolescents. A total of 31581 children and adolescents aged 7–18 years were selected based on the stratified cluster sampling method. Logistics regression models were used to calculate the odds rations (ORs) and 95% confidence interval (95%CI) of the association between different growth patterns and high blood pressure. Mediation effect analyses were applied to estimate the effect of BMI on the increase of blood pressure levels in different growth patterns. In different sex and ages, compared to reference group of normal growth, blood pressure levels and prevalence of high blood pressure of the catch‐up growth were higher, but that of the catch‐down growth were lower. The prevalence of high blood pressure was 11.69%, 16.06%, and 9.68% in normal growth, catch‐up growth, and catch‐down growth, respectively. In total, compared with the normal growth pattern, the ORs (95%CI) of high blood pressure, high systolic blood pressure and high diastolic blood pressure in the catch‐up growth were 1.171(1.073,1.280), 1.110(1.001,1.230) and 1.141(1.025,1.270) (p < .05), respectively. Additionally, the mediation effect of current BMI existed in the association between blood pressure levels and different growth patterns, particularly in boys. Our findings suggested that different growth patterns after birth could modify blood pressure, and the potential risks of high blood pressure could be increased by catch‐up growth at childhood and adolescence.

Physiology of weight regain: Lessons from the classic Minnesota Starvation Experiment on human body composition regulation

Since its publication in 1950, the Biology of Human Starvation, which describes the classic longitudinal Minnesota Experiment of semistarvation and refeeding in healthy young men, has been the undisputed source of scientific reference about the impact of long-term food deprivation on human physiology and behavior. It has been a guide in developing famine and refugee relief programs for international agencies, in exploring the effects of food deprivation on the cognitive and social functioning of those with anorexia nervosa and bulimia nervosa, and in gaining insights into metabolic adaptations that undermine obesity therapy and cachexia rehabilitation. In more recent decades, the application of a systems approach to the analysis of its data on longitudinal changes in body composition, basal metabolic rate, and food intake during the 24 weeks of semistarvation and 20 weeks of refeeding has provided rare insights into the multitude of control systems that govern the regulation of body composition during weight regain. These have underscored an internal (autoregulatory) control of lean-fat partitioning (highly sensitive to initial adiposity), which operates during weight loss and weight regain and revealed the existence of feedback loops between changes in body composition and the control of food intake and adaptive thermogenesis for the purpose of accelerating the recovery of fat mass and fat-free mass. This paper highlights the general features and design of this grueling experiment of simulated famine that has allowed the unmasking of fundamental control systems in human body composition autoregulation. The integration of its outcomes constitutes the "famine reactions" that drive the normal physiology of weight regain and obesity relapse and provides a mechanistic "autoregulation-based" explanation of how dieting and weight cycling, transition to sedentarity, or developmental programming may predispose to obesity. It also provides a system physiology framework for research toward elucidating proteinstatic and adipostatic mechanisms that control hunger-appetite and adaptive thermogenesis, with major implications for a better understanding (and management) of cachexia, obesity, and cardiometabolic diseases.

Anthropometric, body composition, and somatotype characteristics of Japanese young women: Implications for normal-weight obesity syndrome and sarcopenia diagnosis criteria

Aims

The purpose of this study was to examine the anthropometric, body composition, and somatotype characteristics of Japanese young women and to focus on normal-weight obesity syndrome and sarcopenia diagnosis criteria.

Methods

A total of 124 Japanese university freshmen women were measured at body mass index (BMI), percent body fat and skeletal muscle index (SMI), usual gait test, and handgrip strength. The subjects were divided into obesity (≥30% body fat; BMI: ≥25.0 kg/m²), normal-weight obesity (≥30% body fat; BMI: 18.5–24.9 kg/m²), sarcopenia (handgrip, <18 kg; gait speed: ≤0.8 m/s; SMI: <5.7 kg/m²), or presarcopenia (SMI: <5.7 kg/m²). There were no subjects below the sarcopenia diagnosis criteria in usual gait speed, but not for handgrip (0.8%) and SMI (36.3%).

Results

The prevalence of presarcopenia group (36.3%) is higher than in the normal-weight obesity (16.9%) and obesity (4.8%) groups. Anthropometry and sarcopenia diagnosis assessments were significantly higher in normal-weight obesity and standard groups compared with presarcopenia group.

Discussion

The number of young women was higher in the presarcopenia group than in the normal-weight obesity group, suggesting that the improvement of intrinsic skeletal muscle mass rather than fat mass is important for Japanese young women.

Energy homeostasis in apolipoprotein AIV and cholecystokinin-deficient mice

Apolipoprotein AIV (ApoAIV) and cholecystokinin (CCK) are well-known satiating signals that are stimulated by fat consumption. Peripheral ApoAIV and CCK interact to prolong satiating signals. In the present study, we hypothesized that ApoAIV and CCK control energy homeostasis in response to high-fat diet feeding. To test this hypothesis, energy homeostasis in ApoAIV and CCK double knockout (ApoAIV/CCK-KO), ApoAIV knockout (ApoAIV-KO), and CCK knockout (CCK-KO) mice were monitored. When animals were maintained on a low-fat diet, ApoAIV/CCK-KO, ApoAIV-KO, and CCK-KO mice had comparable energy intake and expenditure, body weight, fat mass, fat absorption, and plasma parameters relative to the controls. In contrast, these KO mice exhibited impaired lipid transport to epididymal fat pads in response to intraduodenal infusion of dietary lipids. Furthermore, ApoAIV-KO mice had upregulated levels of CCK receptor 2 (CCK2R) in the small intestine while ApoAIV/CCK-KO mice had upregulated levels of CCK2R in the brown adipose tissue. After 20 wk of a high-fat diet, ApoAIV-KO and CCK-KO mice had comparable body weight and fat mass, as well as lower energy expenditure at some time points. However, ApoAIV/CCK-KO mice exhibited reduced body weight and adiposity relative to wild-type mice, despite having normal food intake. Furthermore, ApoAIV/CCK-KO mice displayed normal fat absorption and locomotor activity, as well as enhanced energy expenditure. These observations suggest that mice lacking ApoAIV and CCK have reduced body weight and adiposity, possibly due to impaired lipid transport and elevated energy expenditure.

Exacerbation of liver steatosis following exposure to famine and overnutrition

SCOPE

People suffering from famine in early life and overnutrition in adulthood may have an increased risk for liver steatosis. We aimed to investigate the effects and mechanisms of early nutrition restriction and overnutrition on de novo lipogenesis in the liver.

METHODS AND RESULTS

Three-wk-old male rats were food restricted for 4 wk and refed a high-fat or normal fat diet individually in metabolic cages for 9 wk. Weight-matched groups were also set up. Fatty acid synthetase expression was measured to estimate de novo lipogenesis in the liver. Parameters of glucose and lipid metabolism were measured with isotope assays. All four groups had comparable body weights. However, the famine high-fat diet group had the highest degree of liver steatosis, the greatest body fat ratio, and insulin resistance. Lipid accumulation, fatty acid synthetase expression, and gluconeogenesis in the liver were significantly higher in the famine and high-fat diet groups (p < 0.05). Moreover, these groups also had markedly lower muscle glucose uptake.

CONCLUSION

Under famine and high-fat refeeding stress, rats were extremely susceptible to developing hepatic steatosis. This is presumably a consequence of upregulation of de novo lipogenesis and enhanced glucose flux from muscle to de novo lipogenesis in the liver.

Polyunsaturated Fatty Acids Stimulate De novo Lipogenesis and Improve Glucose Homeostasis during Refeeding with High Fat Diet

Aims: The recovery of body weight after a period of caloric restriction is accompanied by an enhanced efficiency of fat deposition and hyperinsulinemia—which are exacerbated by isocaloric refeeding on a high fat diet rich in saturated and monounsaturated fatty acids (SFA-MUFA), and poor in polyunsaturated fatty acids (PUFA), and associated with a blunting of de novo lipogenesis in adipose tissue and liver. As high fat diets rich in PUFA have been shown to limit the excess fat deposition and improve glucose homeostasis, we investigated here the extent to which de novo lipogenesis in liver and adipose tissues (white and brown), as well as hepatic oxidative stress, are influenced by refeeding on diets rich in PUFA.

Design: In rats calorically restricted for 14 days and refed for 14 days on isocaloric amounts of a high fat diet rich in lard (i.e., high SFA-MUFA) or in safflower and linseed oils (rich in PUFA), we investigated energy balance, body composition, glycemic profile, and the regulation of fatty acid synthase (rate-limiting enzyme of de novo lipogenesis) in liver, white and brown adipose tissue. We also evaluated oxidative stress in liver and skeletal muscle and markers of hepatic inflammation.

Results: Rats refed the PUFA diet gained less lipids and more proteins compared to rats refed SFA-MUFA diet and showed lower amount of visceral and epididymal white adipose tissue, but increased depots of interscapular brown adipose tissue, with higher expression of the uncoupling protein 1. A significant increase in non-protein respiratory quotient and carbohydrate utilization was found in rats refed PUFA diet. Rats refed PUFA diet showed improved glucose homeostasis, as well as lower triglycerides and cholesterol levels. Fatty acid synthase activity was significantly higher in liver, white and brown adipose tissue, while lipid peroxidation and the degree of inflammation in the liver were significantly lower, in rats refed PUFA diet.

Conclusions: When considering the composition of high fat diets for nutritional rehabilitation, the inclusion of PUFA could be useful for improving protein deposition and maintaining glucose homeostasis, while limiting lipid storage in adipose tissue and oxidative stress and inflammation in the liver.

The Obesity Paradox in Kidney Disease: How to Reconcile it with Obesity Management

Obesity, a risk factor for de novo chronic kidney disease (CKD), confers survival advantages in advanced CKD. This so-called obesity paradox is the archetype of the reverse epidemiology of cardiovascular risks, in addition to the lipid, blood pressure, adiponectin, homocysteine, and uric acid paradoxes. These paradoxical phenomena are in sharp contradistinction to the known epidemiology of cardiovascular risks in the general population. In addition to advanced CKD, the obesity paradox has also been observed in heart failure, chronic obstructive lung disease, liver cirrhosis, and metastatic cancer, as well as in the elderly. These are populations in whom protein-energy wasting and inflammation are strong predictors of early death. Both larger muscle mass and higher body fat provide longevity in these patients, whereas thinner body habitus and weight loss are associated with higher mortality. Muscle mass appears to be superior to body fat in conferring an even greater survival. The obesity paradox may be the result of a time discrepancy between competing risk factors, i.e., overnutrition as the long-term killer versus undernutrition as the short-term killer. Hemodynamic stability of obesity, lipoprotein defense against circulating endotoxins, protective cytokine profiles, toxin sequestration of fat mass, and antioxidation of muscle may play important roles. Despite claims that obesity paradox is a statistical fallacy and a result of residual confounding, the consistency of data and other causality clues suggest a high biologic plausibility. Examining the causes and consequences of the obesity paradox may help discover important pathophysiologic mechanisms leading to improved outcomes in patients with CKD.

Lipid transport in cholecystokinin knockout mice

Cholecystokinin (CCK) is released in response to lipid feeding and regulates pancreatic digestive enzymes vital to the absorption of nutrients. Our previous reports demonstrated that cholecystokinin knockout (CCK-KO) mice fed for 10 weeks of HFD had reduced body fat mass, but comparable glucose uptake by white adipose tissues and skeletal muscles. We hypothesized that CCK is involved in energy homeostasis and lipid transport from the small intestine to tissues in response to acute treatment with dietary lipids. CCK-KO mice with comparable fat absorption had increased energy expenditure and were resistant to HFD-induced obesity. Using intraduodenal infusion of butter fat and intravenous infusion using Liposyn III, we determined the mechanism of lipid transport from the small intestine to deposition in lymph and adipocytes in CCK-KO mice. CCK-KO mice had delayed secretion of Apo B48-chylomicrons, lipid transport to the lymphatic system, and triglyceride (TG)-derived fatty acid uptake by epididymal fat in response to acute treatment of intraduodenal lipids. In contrast, CCK-KO mice had comparable TG clearance and lipid uptake by white adipocytes in response to TGs in chylomicron-like emulsion. Thus, we concluded that CCK is important for lipid transport and energy expenditure to control body weight in response to dietary lipid feeding.

Deep body composition phenotyping during weight cycling: relevance to metabolic efficiency and metabolic risk

Weight cycling may lead to adverse effects on metabolic efficiency (i.e. adaptive thermogenesis or 'metabolic slowing') and metabolic risks (e.g. increased risk for insulin resistance and the metabolic syndrome). In order to investigate these topics, the partitioning of fat and lean mass (i.e. the change in the proportion of both compartments) needs to be extended to the organ and tissue level because metabolic risk differs between adipose tissue depots and lean mass is metabolically heterogeneous being composed of organs and tissues differing in metabolic rate. Contrary to data obtained with severe weight loss and regain in lean people, weight cycling most likely has no adverse effects on fat distribution and metabolic risk in obese patients. There is even evidence for an increased ability of fat storage in subcutaneous fat depots (at the trunk in men and at the limbs in women) with weight cycling that may provide a certain protection from ectopic lipid deposition and thus explain the preservation of a favourable metabolic profile despite weight regain. On the other hand, the mass-specific metabolic rate of lean mass may increase with weight gain and decrease with weight loss mainly because of an increase and respective decrease in the proportion (and/or activity) of metabolically active organ mass. Obese people could therefore have a higher slope of the regression line between resting energy expenditure (REE) and fat-free mass that leads to an overestimation of metabolic efficiency when applied to normalize REE data after weight loss. Furthermore, in addressing the impact of macronutrient composition of the diet on partitioning of lean and fat mass, and the old controversy about whether a calorie is a calorie, we discuss recent evidence in support of a low glycaemic weight maintenance diet in countering weight regain and challenge this concept for weight loss by proposing the opposite.

Maternal high-fat diet modulates hepatic glucose, lipid homeostasis and gene expression in the PPAR pathway in the early life of offspring

Maternal dietary modifications determine the susceptibility to metabolic diseases in adult life. However, whether maternal high-fat feeding can modulate glucose and lipid metabolism in the early life of offspring is less understood. Furthermore, we explored the underlying mechanisms that influence the phenotype. Using C57BL/6J mice, we examined the effects on the offspring at weaning from dams fed with a high-fat diet or normal chow diet throughout pregnancy and lactation. Gene array experiments and quantitative real-time PCR were performed in the liver tissues of the offspring mice. The offspring of the dams fed the high-fat diet had a heavier body weight, impaired glucose tolerance, decreased insulin sensitivity, increased serum cholesterol and hepatic steatosis at weaning. Bioinformatic analyses indicated that all differentially expressed genes of the offspring between the two groups were mapped to nine pathways. Genes in the peroxisome proliferator-activated receptor (PPAR) signaling pathway were verified by quantitative real-time PCR and these genes were significantly up-regulated in the high-fat diet offspring. A maternal high-fat diet during pregnancy and lactation can modulate hepatic glucose, lipid homeostasis, and gene expression in the PPAR signaling in the early life of offspring, and our results suggested that potential mechanisms that influences this phenotype may be related partially to up-regulate some gene expression in the PPAR signalling pathway.

Beneficial effects of a 6-month dietary restriction are time-dependently abolished within 2 weeks or 6 months of refeeding-genome-wide transcriptome analysis in mouse liver

Dietary restriction (DR) has been shown to exert a number of beneficial effects including the prolongation of life span. One of the mechanisms by which DR leads to these advantages seems to be the induction of endogenous antioxidant defense and stress response mechanisms. However, little is known about the persistence of DR benefits after return to an ad libitum diet. In this study, male C57BL/6 mice were fed 75% of a normal diet for 6 months (DR) followed by 6 months of ad libitum refeeding (RF) and compared to a continuously ad libitum fed control group. To study the impact of DR and RF on the liver transcriptome, a global gene expression profile was generated using microarray technology. In comparison, the DR group showed lower body weight, lower triglyceride and cholesterol levels, reduced lipid peroxidation, and a changed hepatic fatty acid pattern. mRNA transcription and activity of antioxidant and phase II enzymes, as well as metallothionein 1 gene expression, were increased and autophagy was induced. Shifting from long-term DR to RF abolished 96% of the DR-mediated changes in differential gene expression within 2 weeks, and after 6 months of refeeding all of the previously differentially expressed genes were similar in both groups. These results indicate that DR has to be maintained continuously to keep its beneficial effects.

Designer peptide antagonist of the leptin receptor with peripheral antineoplastic activity

The obesity hormone leptin has been implicated in the development and progression of different cancer types, and preclinical studies suggest that targeting leptin signaling could be a new therapeutic option for the treatment of cancer, especially in obese patients. To inhibit pro-neoplastic leptin activity, we developed leptin receptor (ObR) peptide antagonists capable of blocking leptin effects in vitro and in vivo. Our lead compound (Allo-aca), however, crosses the blood-brain-barrier (BBB), inducing undesirable orexigenic effects and consequent weight gain. Thus, redesigning Allo-aca to uncouple its central and peripheral activities should produce a superior compound for cancer treatment. The aim of this study was to generate novel Allo-aca analogs and test their biodistribution in vivo and anti-neoplastic activity in vitro in breast and colorectal cancer cells. Examination of several Allo-aca analogs resulted in the identification of the peptidomimetic, d-Ser, that distributed only in the periphery of experimental animals. d-Ser inhibited leptin-dependent-proliferation of ObR-positive breast and colorectal cancer cells in vitro at 1nM concentration without exhibiting any partial agonistic activity. d-Ser efficacy was demonstrated in monolayer and three-dimensional cultures, and its antiproliferative action was associated with the inhibition of several leptin-induced pathways, including JAK/STAT3, MAPK/ERK1/2 and PI3K/AKT, cyclin D1, and E-cadherin. In conclusion, d-Ser is the first leptin-based peptidomimetic featuring peripheral ObR antagonistic activity. The novel peptide may serve as a prototype to develop new therapeutics, particularly for the management of obesity-related cancers.

Developmental origins of adult diseases

There is considerable evidence for the fact that early life environment in human beings are associated with future development of various metabolic diseases. Fetal programming and perinatal events appear to exert effects on later life that are independent of environmental risk factors in adults. Our understanding of the underlying mechanisms are limited and remains unclear. However several animal models and epidemiological studies have shown this association, and it is assumed secondary to the penalties of developmental plasticity. In this review, we amalgamate facts from several disciplines to support this hypothesis.

Recruitment of brown adipose tissue as a therapy for obesity-associated diseases

Brown adipose tissue (BAT) has been recognized for more than 20 years to play a key role in cold-induced non-shivering thermogenesis (CIT, NST), and body weight homeostasis in animals. BAT is a flexible tissue that can be recruited by stimuli (including small molecules in animals), and atrophies in the absence of a stimulus. In fact, the contribution of BAT (and UCP1) to resting metabolic rate and healthy body weight homeostasis in animals (rodents) is now well established. Many investigations have shown that resistance to obesity and associated disorders in various rodent models is due to increased BAT mass and the number of brown adipocytes or UCP1 expression in various depots. The recent discovery of active BAT in adult humans has rekindled the notion that BAT is a therapeutic target for combating obesity-related metabolic disorders. In this review, we highlight investigations performed in rodents that support the contention that activation of BAT formation and/or function in obese individuals is therapeutically powerful. We also propose that enhancement of brown adipocyte functions in white adipose tissue (WAT) will also regulate energy balance as well as reduce insulin resistance in obesity-associated inflammation in WAT.

Lipid overaccumulation and drastic insulin resistance in adult catch-up growth rats induced by nutrition promotion after undernutrition

This study was designed to explore the metabolic changes resulting from catch-up growth in adult (CUGA) induced by varying degrees of nutrition promotion after undernutrition and to confirm whether these changes are transient or not. The CUGA models were developed on rats refed on intakes of normal chow or high-fat diet after a period of caloric restriction. The growth of the rats measured by body weight and length stagnated during caloric restriction and then rapidly accelerated following refeeding. Catch-up growth in adult resulted in an increase in intramuscular and intrahepatic lipid content, visceral fat deposition, and insulin resistance, which is consistent with a transient rise in food efficiency during the early stage of refeeding. In addition, ectopic lipid deposition, visceral fat accumulation, and insulin resistance were more severe in rats refed the high-fat diet than rats refed the normal chow. These findings suggest that CUGA induced by rapid nutrition promotion could result in persistent lipid overaccumulation (increased visceral fat and ectopic lipid deposition) and drastic systemic insulin resistance. The effects of CUGA on metabolic characteristics are dependent on the type of diet that is used for refeeding, especially on the amount of fat intake.

Influence of catch-up growth on islet function and possible mechanisms in rats

OBJECTIVE

The purpose of this study was to examine how catch-up growth modulated islet function and what the detailed mechanisms were, especially at various stages and in different forms, of catch-up growth.

METHODS

We examined the modulation of islet function during catch-up growth by employing an oral glucose tolerance test and gained some insight into the possible mechanisms involved by measuring general physiologic parameters, pancreatic morphometry, insulin content, and the state of chronic oxidative stress. Correlation analyses were used to assess the correlation of insulin/glucose incremental area ratio to other parameters.

RESULTS

The catch-up growth groups resulted in damage to islet function as shown by an increased insulin/glucose incremental area ratio (P ≤ 0.05), smaller relative area of β-cells (P ≤ 0.05), larger relative area of α-cells (P ≤ 0.05), lower insulin content (P ≤ 0.05), increased nitric oxide and malondialdehyde concentrations, and decreased superoxide dismutase concentration (P ≤ 0.05, respectively). With time these changes became increasingly unmarked.

CONCLUSION

Catch-up growth in different stages and forms induces varying degrees of islet dysfunction, possibly by corresponding changes in general physiologic parameters, pancreatic morphometry, insulin content, and the state of chronic oxidative stress.

The thrifty 'catch-up fat' phenotype: its impact on insulin sensitivity during growth trajectories to obesity and metabolic syndrome

The analyses of large epidemiological databases have suggested that infants and children who show catch-up growth, or adiposity rebound at a younger age, are predisposed to the development of obesity, type 2 diabetes and cardiovascular diseases later in life. The pathophysiological mechanisms by which these growth trajectories confer increased risks for these diseases are obscure, but there is compelling evidence that the dynamic process of catch-up growth per se, which often overlaps with adiposity rebound at a younger age, is characterized by hyperinsulinemia and by a disproportionately higher rate in the recovery of body fat than lean tissue (i.e. preferential 'catch-up fat'). This paper first focuses upon the almost ubiquitous nature of this preferential 'catch-up fat' phenotype across the life cycle as a risk factor for obesity and insulin-related complications - not only in infants and children who experienced catch-up growth after earlier fetal or neonatal growth retardation, or after preterm birth, but also in adults who show weight recovery after substantial weight loss owing to famine, disease-cachexia or periodic dieting. It subsequently reviews the evidence indicating that such preferential catch-up fat is primarily driven by energy conservation (thrifty) mechanisms operating via suppressed thermogenesis, with glucose thus spared from oxidation in skeletal muscle being directed towards de novo lipogenesis and storage in white adipose tissue. A molecular-physiological framework is presented which integrates emerging insights into the mechanisms by which this thrifty 'catch-up fat' phenotype crosslinks with early development of insulin and leptin resistance. In the complex interactions between genetic constitution of the individual, programming earlier in life, and a subsequent lifestyle of energy dense foods and low physical activity, this thrifty 'catch-up fat' phenotype--which probably evolved to increase survival capacity in a hunter-gatherer lifestyle of periodic food shortages--is a central event in growth trajectories to obesity and to diseases that cluster into the insulin resistance (metabolic) syndrome.

Frequent intentional weight loss is associated with higher ghrelin and lower glucose and androgen levels in postmenopausal women

Population-based studies suggest that repetitive cycling of weight loss and regain may be associated with future weight gain. Therefore, to better define the relationship between weight cycling, energy homeostasis, and future weight gain, we examined associations between frequent intentional weight loss and hormonal profiles in postmenopausal women. This cross-sectional study evaluated the relationship between a history of frequent weight loss and biomarkers, including serum glucose, insulin, leptin, and ghrelin, as well as sex steroid hormones. We hypothesized that frequent intentional weight loss would be associated with changes in normal appetite and body weight regulatory hormones, favoring increased appetite and weight gain. One hundred fifty-nine healthy, weight stable, sedentary, overweight, postmenopausal women who had been recruited for an exercise intervention participated in this study. History of intentional weight loss (frequency and magnitude) was assessed by questionnaire. Hormonal assays were performed by radioimmunoassay (insulin, leptin, ghrelin, estrogens, androgens, and dehydroepiandrosterone), chemiluminescence immunoassay (insulin-like growth factor-1), and immunometric assay (sex hormone binding globulin). Analysis of variance and regression analyses were used to investigate the relationship between weight loss history and metabolic hormones. A higher degree of weight cycling, characterized by the frequency of intentionally losing more than 10 lb, was associated with an appetite-stimulating hormonal profile, including higher concentrations of ghrelin (P trend = .04), lower glucose (P trend = .047), and to some extent, lower insulin (P trend = .08). Frequent weight loss was also associated with lower androgen concentrations, including androstenedione (P trend = .02), testosterone (P trend = .04), and free testosterone (P trend = .01). No independent associations between the concentrations of leptin or estrogens and weight cycling were observed. This study suggests that frequent intentional weight loss may affect hormones involved in energy regulation.

Hypothalamic neuroendocrine circuitry is programmed by maternal obesity: interaction with postnatal nutritional environment

OBJECTIVE

Early life nutrition is critical for the development of hypothalamic neurons involved in energy homeostasis. We previously showed that intrauterine and early postnatal overnutrition programmed hypothalamic neurons expressing the appetite stimulator neuropeptide Y (NPY) and suppressor proopiomelanocortin (POMC) in offspring at weaning. However, the long-term effects of such programming and its interactions with post-weaning high-fat-diet (HFD) consumption are unclear.

RESEARCH DESIGN AND METHODS

Female Sprague Dawley rats were exposed to chow or HFD for 5 weeks before mating, throughout gestation and lactation. On postnatal day 1, litters were adjusted to 3/litter to induce postnatal overnutrition (vs. 12 in control). At postnatal day 20, half of the rats from each maternal group were weaned onto chow or HFD for 15 weeks. Hypothalamic appetite regulators, and fuel (glucose and lipid) metabolic markers were measured.

RESULTS

Offspring from obese dams gained more weight than those from lean dams independent of post-weaning diet. Maternal obesity interacted with post-weaning HFD consumption to cause greater levels of hyperphagia, adiposity, hyperlipidemia, and glucose intolerance in offspring. This was linked to increased hypothalamic NPY signaling and leptin resistance in adult offspring. Litter size reduction had a detrimental impact on insulin and adiponectin, while hypothalamic NPY and POMC mRNA expression were suppressed in the face of normal energy intake and weight gain.

CONCLUSIONS

Maternal obesity, postnatal litter size reduction and post-weaning HFD consumption caused obesity via different neuroendocrine mechanism. There were strong additive effects of maternal obesity and post-weaning HFD consumption to increase the metabolic disorders in offspring.

Pathophysiology of insulin resistance in subjects born small for gestational age

Over the last 15 years, a number of long-term health risks associated with reduced fetal growth have been identified, including cardiovascular diseases, hypertension, dyslipidaemia and type 2 diabetes. A common feature of these conditions is insulin resistance, which is thought to play a pathogenic role. However, despite abundant data in the literature, it is still difficult to trace the pathway by which fetal events, environmental or not, may lead to increased morbidity later in life. To explain this association, several hypotheses have been proposed pointing to the role of a detrimental fetal environment, a genetic susceptibility or an interaction between the two, and of the particular dynamic changes in adiposity that occur during catch-up growth. The relative impact of early postnatal events in relation to fetal growth has to be considered for designing health policy strategies for early interventions aimed at decreasing disease risk throughout life.

Regulation of fetal growth: consequences and impact of being born small

The first trimester of pregnancy is the time during which organogenesis takes place and tissue patterns and organ systems are established. In the second trimester the fetus undergoes major cellular adaptation and an increase in body size, and in the third trimester organ systems mature ready for extrauterine life. In addition, during that very last period of intrauterine life there is a significant increase in body weight. In contrast to the postnatal endocrine control of growth, where the principal hormones directly influencing growth are growth hormone (GH) and the insulin-like growth factors (IGFs) via the GH-IGF axis, fetal growth throughout gestation is constrained by maternal factors and placental function and is coordinated by growth factors. In general, growth disorders only become apparent postnatally, but they may well be related to fetal life. Thus, fetal growth always needs to be considered in the overall picture of human growth as well as in its metabolic development.

Thrifty energy metabolism in catch-up growth trajectories to insulin and leptin resistance

Catch-up growth early in life (after fetal, neonatal or infantile growth retardation) is a major risk factor for later obesity, type-2 diabetes and cardiovascular diseases. These risks are generally interpreted alongside teleological arguments that environmental exposures which hinder growth early in life lead to programming of 'thrifty mechanisms' that are adaptive during the period of limited nutrient supply (or growth constraint), but which increase risks for diseases during improved nutrition and catch-up growth later in life. This paper addresses this notion of 'thrifty mechanisms' in the light of evidence that catch-up growth is characterized by a disproportionately higher rate of fat gain relative to lean tissue gain, and that such preferential catch-up fat is in part driven by energy conservation mechanisms operating via suppressed thermogenesis. It provides a molecular-physiological framework which integrates emerging insights into mechanisms by which this thrifty 'catch-up fat' phenotype cross-links with insulin and leptin resistance.

Early life programming of obesity and metabolic disease

It is becoming increasingly apparent that conditions experienced in early life play an important role in the long-term health of individuals. Alterations in development due to impaired, excessive or imbalanced growth, both in utero and during critical periods of relative plasticity beyond birth, can lead to the permanent programming of physiological systems. The regulation of energy balance is one area that is receiving particular attention, as rates of obesity and associated metabolic and cardiovascular disease continue to rise. Over recent decades, much progress has been made toward understanding the way in which metabolic tissues and physiological systems develop, and the impact of early life events and nutrition on these processes. It is apparent within human populations that some individuals are better able to maintain an appropriate body weight in the face of an obesogenic environment. Animal models have been widely used for the investigation of differential susceptibility to diet-induced obesity (DIO) and impaired energy balance regulation, and are shedding light on key pathways that may be involved. Alterations in pathways mediating energy homeostasis, outlined below, are likely candidates for programming effects following disturbed growth in early life.

Brain neuropeptide Y and CCK and peripheral adipokine receptors: temporal response in obesity induced by palatable diet

OBJECTIVE

Palatable food disrupts normal appetite regulation, which may contribute to the etiology of obesity. Neuropeptide Y (NPY) and cholecystokinin play critical roles in the regulation of food intake and energy homeostasis, while adiponectin and carnitine palmitoyltransferase (CPT) are important for insulin sensitivity and fatty acid oxidation. This study examined the impact of short- and long-term consumption of palatable high-fat diet (HFD) on these critical metabolic regulators.

METHODS

Male C57BL/6 mice were exposed to laboratory chow (12% fat), or cafeteria-style palatable HFD (32% fat) for 2 or 10 weeks. Body weight and food intake were monitored throughout. Plasma leptin, hypothalamic NPY and cholecystokinin, and mRNA expression of leptin, adiponectin, their receptors and CPT-1, in fat and muscles were measured.

RESULTS

Caloric intake of the palatable HFD group was 2-3 times greater than control, resulting in a 37% higher body weight. Fat mass was already increased at 2 weeks; plasma leptin concentrations were 2.4 and 9 times higher than control at 2 and 10 weeks, respectively. Plasma adiponectin was increased at 10 weeks. Muscle adiponectin receptor 1 was increased at 2 weeks, while CPT-1 mRNA was markedly upregulated by HFD at both time points. Hypothalamic NPY and cholecystokinin content were significantly decreased at 10 weeks.

CONCLUSION

Palatable HFD induced hyperphagia, fat accumulation, increased adiponectin, leptin and muscle fatty acid oxidation, and reduced hypothalamic NPY and cholecystokinin. Our data suggest that the adaptive changes in hypothalamic NPY and muscle fatty acid oxidation are insufficient to reverse the progress of obesity and metabolic consequences induced by a palatable HFD.

Effect of dietary supplementation with INVERSION Femme on slimming, hair loss, and skin and nail parameters in women

In modern society, the ideal of slim women with beautiful hair, skin, and nails is well established. The process of aging, together with an unhealthy diet and little physical exercise, often leads to deterioration of this ideal. Two open clinical trials were conducted to investigate the effect of the proprietary oral supplement INVERSION Femme (Inversion Laboratoires, Hasselt, Belgium) on slimming in overweight women and on hair loss, as well as on skin and nail parameters. A total of 22 overweight women aged 38 to 63 y participated in the study that explored slimming activity. In the hair loss study, 30 women aged 38 to 67 y who had experienced hair loss were examined. All 52 women in both groups were further evaluated for skin (ie, wrinkles and hydration) and nail improvement. The active ingredients in INVERSION Femme, subdivided into 2 different capsules, exhibit antioxidative activity and nutritional function; in addition, they contribute to enhanced microcirculation, tonus, and thermogenesis. Weight reduction and slimming were measured after INVERSION Femme was taken for 28 and 58 d. All women showed significant reductions in weight, body fat, and thigh circumference. During the second month of treatment, subjects showed an average 50% reduction in hair loss. INVERSION Femme is a potent "all-in-one" antiaging dietary supplement that causes significant slimming and reduction in hair loss, as well as visible improvement in skin and nail structure.

Does feed restriction and re-alimentation differently affect lipid content and metabolism according to muscle type in pigs (Sus scrofa)?

This study aimed to investigate whether feed restriction and re-alimentation differently affect lipid content and activities of lipogenic or catabolic enzymes according to muscle types in pigs. At around 28 kg body mass (BW), sixty pigs (n=30 per group) were allocated to either ad libitum (AL) or restricted/re-feeding (RA) regimens. After feed restriction (80 kg BW), lipid content was reduced (P<0.01) in the oxidative rhomboideus (RH) as in the glycolytic biceps femoris (BF) muscles of RA pigs compared with AL pigs. Lower activities (P<0.05) of the lipogenic enzymes fatty acid synthase (FAS) and malic enzyme (ME) were observed in the RH but not in the BF of RA vs. AL pigs. After re-feeding (110 kg BW), lipid content was restored in the RH, but was still 12% lower (P<0.05) in the BF of RA compared with AL pigs. In the RH, the trend for an enhanced FAS activity and for a smaller weight-related decrease of ME activity in RA pigs than AL pigs during re-feeding, may have contributed to the muscle fat recovery observed in the RA pigs. In the BF, higher oxidative enzyme activities (P<0.10) in RA pigs compared to AL pigs might explain the incomplete lipid recovery observed after re-feeding in the former animals. In conclusion, metabolic activities in response to restriction and re-feeding differed according to muscle metabolic type.

The Obesity Epidemic: Current and Future Pharmacological Treatments

The unabated rise in the prevalence of obesity is a challenge for global health care systems. Efforts to reverse this trend by dietary or behavioral counseling have not been successful, which has stimulated efforts to find a role for pharmacotherapy. Currently only a small number of antiobesity drugs are approved for long-term use and only a few compounds are in clinical development. Despite recent progress in the understanding of the regulation of energy balance, drug discovery has been less productive than expected. In the present review, the clinically available antiobesity agents are discussed. Examples of drug candidates that are currently in development are given and the possible future range of antiobesity agents is illustrated by the targets being addressed in drug discovery. Finally, the efficacy of antiobesity agents and their value in the treatment of obesity are assessed in comparison with other therapeutic approaches, such as surgery and changes in lifestyle.

Is the CCK2 receptor essential for normal regulation of body weight and adiposity?

Cholecystokinin (CCK) is a gastrointestinal satiety signal released from the duodenum to terminate feeding, via CCK1 receptors. CCK2 receptors are considered to be involved in anxiety. CCK2 receptor knockout mice have increased body weight and food intake. Little is known regarding the effects of CCK2 receptor deficiency on adipose distribution and hypothalamic feeding regulators such as neuropeptide Y (NPY), a powerful stimulator of feeding. Adult (10 week) CCK2 receptor knockout and wild-type mice were anaesthetized and killed by decapitation. Brain sections, organs and fat tissue were dissected. Plasma leptin, insulin and brain NPY content were measured by radioimmunoassay. Female CCK2 receptor knockout mice weighed more than control mice (22.0 +/- 0.2 vs. 19.9 +/- 0.4 g, P < 0.05), with this difference being less marked in male mice (26.4 +/- 0.4 vs. 25.6 +/- 0.6 g). Fat masses in all locations sampled were significantly smaller in CCK2 receptor knockout mice of both genders (P < 0.05), resulting in lower plasma leptin and insulin levels. NPY concentrations were significantly increased in arcuate nucleus and anterior hypothalamus in both male and female CCK2 receptor knockout mice, and total hypothalamic NPY content was increased by 7 and 9% in males and females, respectively (P < 0.05). CCK2 receptor deletion was associated with increased body weight and hypothalamic NPY content, but reduced fat masses and plasma leptin and insulin. Increased NPY might contribute to increased food intake in CCK2 receptor knockout mice. Further work needs to focus on the metabolic changes.

Reductions in caloric intake and early postnatal growth prevent glucose intolerance and obesity associated with low birthweight

AIMS/HYPOTHESIS

Low birthweight (LBW) and rapid postnatal weight gain, or catch-up growth, are independent risk factors for the development of obesity and diabetes during adult life. Individuals who are both small at birth and have postnatal catch-up growth are at the highest risk. We hypothesised that dietary interventions designed to attenuate catch-up growth in LBW subjects may have long-term beneficial consequences.

MATERIALS AND METHODS

We used our previously described mouse model of LBW-associated diabetes, created by restricting maternal food intake to 50% during the last week of gestation. Control (C) dams and dams that had been subjected to undernutrition (U) were then provided either chow ad libitum after delivery or 50% food restriction on a per-day basis from delivery until weaning. We designated the resulting four groups control-control (CC), undernutrition-control (UC), control-undernutriton (CU) and undernutrition-undernutrition (UU), indicating the prenatal and postnatal experimental conditions, respectively. Carbohydrate metabolism and adiposity were assessed prospectively in offspring until age 6 months.

RESULTS

Males that were small at birth and exhibited early postnatal catch-up growth developed glucose intolerance and obesity by age 6 months. In contrast, LBW mice without catch-up growth (UU) remained smaller than controls (CC), and glucose intolerance and obesity was prevented. Similarly, mice with normal birthweight that had blunted catch-up growth (CU) were leaner and had better tolerance test than CC mice. Catch-up growth during the first week of life correlated better than birthweight with glucose, fat mass and glucose tolerance up to 6 months of age.

CONCLUSIONS/INTERPRETATION

Prevention of early catch-up growth reversed the development of glucose intolerance and obesity in our mouse model of LBW-associated diabetes.

Adipose targets for obesity drug development

The prevalence of obesity is increasing rapidly in most parts of the world and effective therapeutic drugs are urgently needed. The discovery of leptin in 1994 initiated a new understanding of adipose tissue function, and adipose tissue is now known to not only store and release fatty acids, but also to produce a wealth of factors that have an impact on the regulation of body weight and blood glucose homeostasis. Also, adipocytes express proteins that engage signalling pathways playing important roles in fuel substrate and energy metabolism. These proteins constitute a diverse array of adipose target candidates for the development of drugs to treat obesity. Some of these potential targets have been validated and are now in drug development stages, providing hope that the current obesity epidemic can be addressed by effective drug treatments in the near future.

A role for skeletal muscle stearoyl-CoA desaturase 1 in control of thermogenesis

An enhanced metabolic efficiency for accelerating the recovery of fat mass (or catch-up fat) is a characteristic feature of body weight regulation after weight loss or growth retardation and is the outcome of an "adipose-specific" suppression of thermogenesis, i.e., a feedback control system in which signals from the depleted adipose tissue fat stores exert a suppressive effect on thermogenesis. Using a previously described rat model of semistarvation-refeeding in which catch-up fat results from suppressed thermogenesis per se, we report here that the gene expression of stearoyl-coenzyme A desaturase 1 (SCD1) is elevated in skeletal muscle after 2 wk of semistarvation and remains elevated in parallel to the phase of suppressed thermogenesis favoring catch-up fat during refeeding. These elevations in the SCD1 transcript are skeletal muscle specific and are associated with elevations in microsomal Delta9 desaturase enzyme activity, in the Delta9 desaturation index, and in the relative content of SCD1-derived monounsaturates in several lipid fractions extracted from skeletal muscle. An elevated skeletal muscle SCD1, by desaturating the products of de novo lipogenesis and diverting them away from mitochondrial oxidation, would inhibit substrate cycling between de novo lipogenesis and lipid oxidation, thereby leading to a state of suppressed thermogenesis that regulates the body's fat stores.

Long-term metabolic consequences of being born small for gestational age

During the last 15 years, a number of long-term health risks associated with reduced fetal growth have been identified, including cardiovascular diseases and the insulin-resistance syndrome or one of its components: hypertension, dyslipidemia, impaired glucose tolerance or Type 2 diabetes. A common feature of these conditions is the presence of high insulin levels, which are thought to play a pathogenic role. However, despite abundant data in the literature, it is still difficult to trace the pathway by which fetal events, environmental or not, may lead to the increased morbidity later in life. To explain this association, several hypotheses have been proposed pointing to the critical role of either a detrimental fetal environment or a genetic susceptibility, or indicating interaction of both. Clearly, not all subjects born small for gestational age are at the same risk of developing these complications. It appears that individuals at particular risk are those who were thin at birth and had a subsequent catch-up in body mass index, irrespective of the degree of adiposity in adulthood. It is suggested that this particular dynamic change in adiposity has a critical role in the development of long-term metabolic complications. Therefore, it is important to consider the relative impact of early postnatal events in relation to fetal growth to the diseases risk throughout life in forming health policy strategies towards eventual early interventions.

Regulation of fat storage via suppressed thermogenesis: a thrifty phenotype that predisposes individuals with catch-up growth to insulin resistance and obesity

Catch-up growth during infancy and childhood is increasingly recognized as a major risk factor for later development of insulin-related complications and chronic diseases, namely abdominal obesity, type 2 diabetes and cardiovascular disease. As catch-up growth per se is characterized by insulin resistance, hyperinsulinaemia and an accelerated rate of fat storage (i.e., catch-up fat) even in the absence of hyperphagia, the possibility arises that suppressed thermogenesis in certain organs/tissues - for the purpose of enhancing the efficiency of catch-up fat - also plays a role in the pathophysiological consequences of catch-up growth. Here, the evidence for the existence of an adipose-specific control of thermogenesis, the suppression of which contributes to catch-up fat, is reviewed. Recent findings suggest that such suppression of thermogenesis is accompanied by hyperinsulinaemia, insulin resistance in skeletal muscle and insulin hyperresponsiveness in adipose tissue, all of which precede the appearance of excess body fat, central fat distribution and elevations in intramyocellular triglyceride or circulating lipid concentrations. These findings underscore a role for suppressed thermogenesis per se as an early event in the pathophysiology of catch-up growth. It is proposed that, in its evolutionary adaptive role to spare glucose for the rapid rebuilding of an adequate fat reserve (for optimal survival capacity during intermittent famine), suppressed thermogenesis in skeletal muscle constitutes a thrifty phenotype that confers to the phase of catch-up growth its high sensitivity to the development of insulin resistance and hyperinsulinaemia. In the context of the complex interactions between earlier reprogramming and a modern lifestyle characterized by nutritional abundance and low physical activity, this thrifty 'catch-up fat phenotype' is a central event that predisposes individuals with catch-up growth to abdominal obesity, type 2 diabetes and cardiovascular disease.

Mechanistic model of fuel selection in the muscle

Fuel selection in human muscle is key to explaining insulin resistance. In obesity and type 2 diabetes mellitus, there is an increased content of lipid within and around muscle fibers. Changes in muscle fuel partitioning of lipid, between oxidation and storage of fat, contribute to the accumulation of intramuscular triglycerides and to the pathogenesis of both obesity and type 2 diabetes mellitus. A mathematical model of the aggregated metabolism in skeletal muscle was developed and the effects of fuel selection for lean and obese individuals under fasting conditions, insulin-stimulated conditions, and oscillating insulin conditions were examined. Model results were complementary to prior observations that elevated lipid oxidation during insulin-stimulated conditions is correlated with insulin resistance. The model also adequately simulated metabolic inflexibility between fat and glucose oxidation in the obese individual. A novel sensitivity analysis indicated the strong interaction effects of parameters of glucose and lipid oxidation pathways on the variables of each pathway.