Bruss MD, Khambatta CF, Ruby MA, Aggarwal I, Hellerstein MK. Calorie restriction increases fatty acid synthesis and whole body fat oxidation rates. Am J Physiol Endocrinol Metab 298: E108-E116, 2010. First published November 3, 2009 zdoi:10.1152/ajpendo.00524.2009.-Calorie restriction (CR) increases longevity and retards the development of many chronic diseases, but the underlying metabolic signals are poorly understood. Increased fatty acid (FA) oxidation and reduced FA synthesis have been hypothesized to be important metabolic adaptations to CR. However, at metabolic steady state, FA oxidation must match FA intake plus synthesis; moreover, FA intake is low, not high, during CR. Therefore, it is not clear how FA dynamics are altered during CR. Accordingly, we measured food intake patterns, whole body fuel selection, endogenous FA synthesis, and gene expression in mice on CR. Within 2 days of CR being started, a shift to a cyclic, diurnal pattern of whole body FA metabolism occurred, with an initial phase of elevated endogenous FA synthesis [respiratory exchange ratio (RER) Ͼ1.10, lasting 4 -6 h after food provision], followed by a prolonged phase of FA oxidation (RER ϭ 0.70, lasting 18 -20 h). CR mice oxidized four times as much fat per day as ad libitum (AL)-fed controls (367 Ϯ 19 vs. 97 Ϯ 14 mg/day, P Ͻ O.001) despite reduced energy intake from fat. This increase in FA oxidation was balanced by a threefold increase in adipose tissue FA synthesis compared with AL. Expression of FA synthase and acetyl-CoA carboxylase mRNA were increased in adipose and liver in a timedependent manner. We conclude that CR induces a surprising metabolic pattern characterized by periods of elevated FA synthesis alternating with periods of FA oxidation disproportionate to dietary FA intake. This pattern may have implications for oxidative damage and disease risk. fat synthesis; lipogenesis; palmitoleate; heavy water CALORIE RESTRICTION (CR) delays the development of chronic disease and prolongs lifespan in mice (1,17,27,34). These effects correlate with a rapid induction in the expression of certain genes that persist as long as animals remain on CR (10, 36) even after energy balance is restored. These observations suggest the presence of a chronic signal of reduced energy availability that persists after energy balance has been reestablished. However, the underlying metabolic signals and adaptations responsible are not fully understood.Mice on CR regimens have been reported to exhibit increased expression of genes for fatty acid (FA) oxidation and decreased expression of genes for FA synthesis compared with ad libitum (AL)-fed controls (6,7,30,38). Due to differential entry points into the electron transport chain, a metabolic shift from carbohydrate to FA oxidation may reduce the production of reactive oxygen species (ROS) (15). A shift to FA oxidation thereby represents a potential mechanism for reduced oxidative damage, which has been proposed as a potential explanation for the health benefits of CR (14,15,29,35). It has also be...

Objective: Unrefined, complex carbohydrates and lean protein diets are used to combat obesity, although it's unknown whether more frequent meals may improve this response. The effects of consuming traditional ($15%) versus higher ($35%) protein intakes as three or six meals/day on abdominal fat, postprandial thermogenesis (TEM), and cardiometabolic biomarkers in overweight individuals during 28 days of energy balance (BAL) and deficit (NEG), respectively were compared. Design and Methods: Overweight individuals (n ¼ 30) were randomized into three groups: two highprotein groups (35% of energy) consumed as three (HP3) or six (HP6) meals/day and one group consumed three meals/day of a traditional intake (TD3). Following a 5-day baseline control (CON), subjects consumed their respective diets throughout a 56-day intervention consisting of two, 28 day phases: a BAL followed by a NEG phase (75% of energy needs). Total body fat (BF) and abdominal BF (ABF), body weight (BW), TEM, and fasting biomarkers were assessed at the end of CON, BAL, and NEG phases. Results: BW remained stable throughout CON and BAL in all groups, whereas BF (P < 0.001) and ABF (P < 0.01) decreased in HP groups and lean body mass (LBM) and leptin increased in HP6. Following NEG, BW decreased in all groups. BF, ABF, and leptin decreased in HP groups; LBM remained higher (P < 0.05), and TEM was highest in HP6 (P < 0.05). Conclusions: Consuming increased protein ($35%) more frequently (6Â) throughout the day decreases BF and ABF, increases LBM and TEM, and favorably affects adipokines more than current recommendations for macronutrients consumed over three meals/day in overweight individuals during both BAL and NEG.

SummarySerine hydrolases are a large family of multifunctional enzymes known to influence obesity. Here, we performed activity-based protein profiling to assess the functional level of serine hydrolases in liver biopsies from lean and obese humans in order to gain mechanistic insight into the pathophysiology of metabolic disease. We identified reduced hepatic activity of carboxylesterase 2 (CES2) and arylacetamide deacetylase (AADAC) in human obesity. In primary human hepatocytes, CES2 knockdown impaired glucose storage and lipid oxidation. In mice, obesity reduced CES2, whereas adenoviral delivery of human CES2 reversed hepatic steatosis, improved glucose tolerance, and decreased inflammation. Lipidomic analysis identified a network of CES2-regulated lipids altered in human and mouse obesity. CES2 possesses triglyceride and diacylglycerol lipase activities and displayed an inverse correlation with HOMA-IR and hepatic diacylglycerol concentrations in humans. Thus, decreased CES2 is a conserved feature of obesity and plays a causative role in the pathogenesis of obesity-related metabolic disturbances.

ObjectiveEpigenetic modifications contribute to the etiology of type 2 diabetes.MethodWe performed genome-wide methylome and transcriptome analysis in liver from severely obese men with or without type 2 diabetes and non-obese men to discover aberrant pathways underlying the development of insulin resistance. Results were validated by pyrosequencing.ResultWe identified hypomethylation of genes involved in hepatic glycolysis and insulin resistance, concomitant with increased mRNA expression and protein levels. Pyrosequencing revealed the CpG-site within ATF-motifs was hypomethylated in four of these genes in liver of severely obese non-diabetic and type 2 diabetic patients, suggesting epigenetic regulation of transcription by altered ATF-DNA binding.ConclusionSeverely obese non-diabetic and type 2 diabetic patients have distinct alterations in the hepatic methylome and transcriptome, with hypomethylation of several genes controlling glucose metabolism within the ATF-motif regulatory site. Obesity appears to shift the epigenetic program of the liver towards increased glycolysis and lipogenesis, which may exacerbate the development of insulin resistance.

The endocannabinoid (EC) system regulates food intake and energy metabolism. Cannabinoid receptor type 1 (CB1) antagonists show promise in the treatment of obesity and its metabolic consequences. Although the reduction in adiposity resulting from therapy with CB1 antagonists may not account fully for the concomitant improvements in dyslipidemia, direct effects of overactive EC signaling on plasma lipoprotein metabolism have not been documented. The present study used a chemical approach to evaluate the direct effects of increased EC signaling in mice by inducing acute elevations of endogenously produced cannabinoids through pharmacological inhibition of their enzymatic hydrolysis by isopropyl dodecylfluorophosphonate (IDFP). Acute IDFP treatment increased plasma levels of triglyceride (TG) (2.0-to 3.1-fold) and cholesterol (1.3-to 1.4-fold) in conjunction with an accumulation in plasma of apolipoprotein (apo)E-depleted TG-rich lipoproteins. These changes did not occur in either CB1-null or apoE-null mice, were prevented by pretreatment with CB1 antagonists, and were not associated with reduced hepatic apoE gene expression. Although IDFP treatment increased hepatic mRNA levels of lipogenic genes (Srebp1 and Fas), there was no effect on TG secretion into plasma. Instead, IDFP treatment impaired clearance of an intravenously administered TG emulsion, despite increased postheparin lipoprotein lipase activity. Therefore, overactive EC signaling elicits an increase in plasma triglyceride levels associated with reduced plasma TG clearance and an accumulation in plasma of apoE-depleted TG-rich lipoproteins. These findings suggest a role of CB1 activation in the pathogenesis of obesity-related hypertriglyceridemia and underscore the potential efficacy of CB1 antagonists in treating metabolic disease.2-arachidonoylglycerol ͉ hypertriglyceridemia ͉ monoaylglycerol lipase ͉ organophosphorus ͉ cannabinoid receptor O besity elicits a cluster of interrelated disorders, termed the ''metabolic syndrome,'' that increases the risk of cardiovascular disease (1). Epidemiological and genetic data indicate that dysregulation of the endocannabinoid (EC) system increases adiposity in humans (2-4). Pharmacological or genetic ablation of the cannabinoid type 1 receptor (CB1) in normal mice and in diet-induced and genetic mouse models of obesity results in a transient hypophagic response mediated through the hypothalamus, but there also are prolonged effects on weight loss, adiposity, and normalization of metabolic parameters, including plasma lipids (5-11). These effects suggest that the improvement in adiposity-related measures with CB1 inactivation is not limited to reduced food intake, a major known effect of CB1 inactivation (5, 11). CB1 activation in liver increases de novo lipogenesis and decreases fatty acid oxidation (12, 13). High-fat diet or chronic ethanol treatment increases cannabinoid signaling tone via increased hepatic CB1 receptor density and EC levels leading to CB1-mediated hepatic steatosis (12, 13). These observations...