Meal timing and its role in obesity and associated diseases.

Meal timing emerges as a crucial factor influencing metabolic health that can be explained by the tight interaction between the endogenous circadian clock and metabolic homeostasis. Mistimed food intake, such as delayed or nighttime consumption, leads to desynchronization of the internal circadian clock and is associated with an increased risk for obesity and associated metabolic disturbances such as type 2 diabetes and cardiovascular diseases. Conversely, meal timing aligned with cellular rhythms can optimize the performance of tissues and organs. In this review, we provide an overview of the metabolic effects of meal timing and discuss the underlying mechanisms. Additionally, we explore factors influencing meal timing, including internal determinants such as chronotype and genetics, as well as external influences like social factors, cultural aspects, and work schedules. This review could contribute to defining meal-timing-based recommendations for public health initiatives and developing guidelines for effective lifestyle modifications targeting the prevention and treatment of obesity and associated metabolic diseases. Furthermore, it sheds light on crucial factors that must be considered in the design of future food timing intervention trials.

Isomaltulose Enhances GLP-1 and PYY Secretion to a Mixed Meal in People With or Without Type 2 Diabetes as Compared to Saccharose.

SCOPE: Secretion of the gut hormones glucagon-like peptide (GLP-1) and peptide YY (PYY) are induced by nutrients reaching the lower small intestine which regulate insulin and glucagon release, inhibit appetite, and may improve ß-cell regeneration. The aim is to test the effect of a slowly digested isomaltulose (ISO) compared to the rapidly digested saccharose (SAC) as a snack given 1 h before a standardized mixed meal test (MMT) on GLP-1, PYY, glucose-dependent insulinotropic peptide (GIP), and metabolic responses in participants with or without type 2 diabetes (T2DM). METHODS AND RESULTS: Fifteen healthy volunteers and 15 patients with T2DM consumed either 50 g ISO or SAC 1 h preload of MMT on nonconsecutive days. Clinical parameters and incretin hormones are measured throughout the whole course of MMT. Administration of 50 g ISO as compared to SAC induced a significant increase in GLP-1, GIP, and PYY responses over 2 h after intake of a typical lunch in healthy controls. Patients with T2DM showed reduced overall responses of GLP-1 and delayed insulin release compared to controls while ISO significantly enhanced the GIP and almost tripled the PYY response compared to SAC. CONCLUSION: A snack containing ISO markedly enhances the release of the metabolically advantageous gut hormones PYY and GLP-1 and enhances GIP release in response to a subsequent complex meal.

Effects of reducing free sugars on 24-hour glucose profiles and glycemic variability in subjects without diabetes.

Background: The Western diet, especially beverages and high processed food products, is high in sugars which are associated with the development of obesity and diabetes. The reduction of refined carbohydrates including free and added sugars improves glycemic control in individuals with diabetes, but the data regarding effects in subjects without diabetes are limited. Objective: This study aimed to evaluate the effects of reducing free sugar intake on 24-h glucose profiles and glycemic variability using continuous glucose monitoring (CGM). Methods: In the randomized controlled study, 21 normal weight and overweight/obese subjects (BMI 18-40 kg/m2) without diabetes were assigned to a 4-week reduced-sugar (RS) diet or control diet after a 2-week baseline phase. During the baseline phase, all participants were advised not to change their habitual diet. During the intervention phase, RS participants were asked to avoid added sugar and white flour products, whereas participants of the control group were requested to proceed their habitual diet. Anthropometric parameters and HbA1c were assessed before and at the end of the intervention phase. Interstitial glucose was measured using continuous glucose monitoring (CGM), and the food intake was documented by dietary records for 14 consecutive days during the baseline phase and for the first 14 consecutive days during the intervention phase. Mean 24-h glucose as well as intra- and inter-day indices of glucose variability, i.e., standard deviation (SD) around the sensor glucose level, coefficient of variation in percent (CV), mean amplitude of glucose excursions (MAGE), continuous overlapping net glycemic action (CONGA), and mean absolute glucose (MAG), were calculated for the baseline and intervention phases. Results: During the intervention, the RS group decreased the daily intake of sugar (i.e., -22.4 ± 20.2 g, -3.28 ± 3.61 EN %), total carbohydrates (-6.22 ± 6.92 EN %), and total energy intake (-216 ± 108 kcal) and increased the protein intake (+2.51 ± 1.56 EN %) compared to the baseline values, whereby this intervention-induced dietary changes differed from the control group. The RS group slightly reduced body weight (-1.58 ± 1.33 kg), BMI, total fat, and visceral fat content and increased muscle mass compared to the baseline phase, but these intervention-induced changes showed no differences in comparison with the control group. The RS diet affected neither the 24-h mean glucose levels nor intra- and inter-day indices of glucose variability, HbA1c, or diurnal glucose pattern in the within- and between-group comparisons. Conclusion: The dietary reduction of free sugars decreases body weight and body fat which may be associated with reduced total energy intake but does not affect the daily mean glucose and glycemic variability in individuals without diabetes. Clinical trial registration: German Clinical Trials Register (DRKS); identifier: DRKS00026699.

Determination of the autophagic flux in murine and human peripheral blood mononuclear cells.

The autophagy lysosomal system (ALS) is crucial for cellular homeostasis, contributing to maintain whole body health and alterations are associated with diseases like cancer or cardiovascular diseases. For determining the autophagic flux, inhibition of lysosomal degradation is mandatory, highly complicating autophagy measurement in vivo. To overcome this, herein blood cells were used as they are easy and routinely to isolate. Within this study we provide detailed protocols for determination of the autophagic flux in peripheral blood mononuclear cells (PBMCs) isolated from human and, to our knowledge the first time, also from murine whole blood, extensively discussing advantages and disadvantages of both methods. Isolation of PBMCs was performed using density gradient centrifugation. To minimize changes on the autophagic flux through experimental conditions, cells were directly treated with concanamycin A (ConA) for 2 h at 37°C in their serum or for murine cells in serum filled up with NaCl. ConA treatment decreased lysosomal cathepsins activity and increased Sequestosome 1 (SQSTM1) protein and LC3A/B-II:LC3A/B-I ratio in murine PBMCs, while transcription factor EB was not altered yet. Aging further enhanced ConA-associated increase in SQSTM1 protein in murine PBMCs but not in cardiomyocytes, indicating tissue-specific differences in autophagic flux. In human PBMCs, ConA treatment also decreased lysosomal activity and increased LC3A/B-II protein levels, demonstrating successful autophagic flux detection in human subjects. In summary, both protocols are suitable to determine the autophagic flux in murine and human samples and may facilitate a better mechanistic understanding of altered autophagy in aging and disease models and to further develop novel treatment strategies.

Implication of sugar, protein and incretins in excessive glucagon secretion in type 2 diabetes after mixed meals.

AIMS: Amino acids powerfully release glucagon but their contribution to postprandial hyperglucagonemia in type 2 diabetes remains unclear. Exogenously applied GIP stimulates, while GLP-1 inhibits, glucagon secretion in humans. However, their role in mixed meals is unclear, which we therefore characterized. METHODS: In three experiments, participants with type 2 diabetes and obese controls randomly received different loads of sugars and/or proteins. In the first experiment, participants ingested the rapidly cleaved saccharose (SAC) or slowly cleaved isomaltulose (ISO) which is known to elicit opposite profiles of GIP and GLP-1 secretion. In the second one participants received test meals which contained saccharose or isomaltulose in combination with milk protein. The third set of participants underwent randomized oral protein tests with whey protein or casein. Incretins, glucagon, C-peptide, and insulin were profiled by specific immunological assays. RESULTS: 50 g of the sugars alone suppressed glucagon in controls but slightly less in type 2 diabetes patients. Participants with type 2 diabetes showed excessive glucagon responses within 15 min and lasting over 3 h, while the obese controls showed small initial and delayed greater glucagon responses to mixed meals. The release of GIP was significantly faster and greater with SAC compared to ISO, while GLP-1 showed an inverse pattern. The glucagon responses to whey or casein were only moderately increased in type 2 diabetes patients without a left shift of the dose response curve. CONCLUSIONS: The rapid hypersecretion of glucagon after mixed meals in type 2 diabetes patients compared to controls is unaffected by endogenous incretins. The defective suppression of glucagon by glucose combined with hypersecretion to protein is required for the exaggerated response. CLINICAL TRIALS NUMBERS: NCT03806920, NCT02219295, NCT04564391.

Acute and long-term exercise adaptation of adipose tissue and skeletal muscle in humans: a matched transcriptomics approach after 8-week training-intervention.

BACKGROUND: Exercise exerts many health benefits by directly inducing molecular alterations in physically utilized skeletal muscle. Molecular adaptations of subcutaneous adipose tissue (SCAT) might also contribute to the prevention of metabolic diseases. AIM: To characterize the response of human SCAT based on changes in transcripts and mitochondrial respiration to acute and repeated bouts of exercise in comparison to skeletal muscle. METHODS: Sedentary participants (27 ± 4 yrs) with overweight or obesity underwent 8-week supervised endurance exercise 3×1h/week at 80% VO2peak. Before, 60 min after the first and last exercise bout and 5 days post intervention, biopsies were taken for transcriptomic analyses and high-resolution respirometry (n = 14, 8 female/6 male). RESULTS: In SCAT, we found 37 acutely regulated transcripts (FC > 1.2, FDR < 10%) after the first exercise bout compared to 394, respectively, in skeletal muscle. Regulation of only 5 transcripts overlapped between tissues highlighting their differential response. Upstream and enrichment analyses revealed reduced transcripts of lipid uptake, storage and lipogenesis directly after exercise in SCAT and point to ß-adrenergic regulation as potential major driver. The data also suggest an exercise-induced modulation of the circadian clock in SCAT. Neither term was associated with transcriptomic changes in skeletal muscle. No evidence for beigeing/browning was found in SCAT along with unchanged respiration. CONCLUSIONS: Adipose tissue responds completely distinct from adaptations of skeletal muscle to exercise. The acute and repeated reduction in transcripts of lipid storage and lipogenesis, interconnected with a modulated circadian rhythm, can counteract metabolic syndrome progression toward diabetes.

Multiple sclerosis and circadian rhythms: Can diet act as a treatment?

Multiple sclerosis (MS) is an autoimmune inflammatory and neurodegenerative disease of the central nervous system (CNS) with increasing incidence and prevalence. MS is associated with inflammatory and metabolic disturbances that, as preliminary human and animal data suggest, might be mediated by disruption of circadian rhythmicity. Nutrition habits can influence the risk for MS, and dietary interventions may be effective in modulating MS disease course. Chronotherapeutic approaches such as time-restricted eating (TRE) may benefit people with MS by stabilizing the circadian clock and restoring immunological and metabolic rhythms, thus potentially counteracting disease progression. This review provides a summary of selected studies on dietary intervention in MS, circadian rhythms, and their disruption in MS, including clock gene variations, circadian hormones, and retino-hypothalamic tract changes. Furthermore, we present studies that reported diurnal variations in MS, which might result from circadian disruption. And lastly, we suggest how chrononutritive approaches like TRE might counteract MS disease activity.

Effects of Exercise and Omega-3-Supplemented, High-Protein Diet on Inflammatory Markers in Serum, on Gene Expression Levels in PBMC, and after Ex Vivo Whole-Blood LPS Stimulation in Old Adults.

Inflammaging is related to cell senescence and reflects an erratic immune system, which promotes age-associated diseases. Exercise and nutrition, particularly omega-3 fatty acids, are able to affect inflammation. Therefore, we examined the effects of an 8-week exercise and dietary intervention on the inflammatory response in community-dwelling old adults. All participants received weekly vibration and home-based resistance exercise. Furthermore, participants were randomized to either a control, high-protein (1.2-1.5 g/kg), or high-protein, omega-3-enriched (2.2 g/day) diet. Before and after treatment, inflammatory markers in fasting serum and after whole-blood ex vivo lipopolysaccharide (LPS) stimulation were assessed. Gene expression levels of inflammatory markers were quantified in peripheral blood mononuclear cells (PBMC). Sixty-one participants (age: 70.6 ± 4.7 years; 47% men) completed the study. According to generalized linear mixed models, a high-protein, omega-3-enriched diet decreased circulating anti-inflammatory interleukin (IL-) 10 and IL-1 receptor antagonist (IL-1RA). Sex-stratified analyses showed also significantly reduced pro-inflammatory markers in men with a high-protein, omega-3-enriched diet. Gene expression of IL-1RA was significantly reduced after both protein-enriched diets compared with controls. In comparison to a high-protein diet, exercise alone showed lower LPS-induced release of c-c motif chemokine ligand-2 (CCL-2), which tended to be more pronounced in men compared with women. Eight weeks of a high-protein, omega-3-enriched diet combined with exercise decreased circulating anti-inflammatory markers, and pro-inflammatory markers in men. A high-protein diet attenuated anti-inflammatory markers on gene expression level in PBMC. Exercise alone resulted in a lower pro-inflammatory response to LPS-exposure in whole-blood cultures.

Validation of a Smartphone Application for the Assessment of Dietary Compliance in an Intermittent Fasting Trial.

Accurate dietary analysis of energy, nutrient intake, and meal timing in human studies using traditional dietary assessment methods (e.g., food records) is challenging and time-consuming. The widespread use of smartphones, tablets, and nutrition applications (apps) can overcome some of these problems. The objective of this study was to evaluate the validity of an FDDB smartphone app and food database compared with PRODI®-a professional platform for nutritional counselling using the German Nutrient Database. Dietary records were collected from 10 subjects participating in the crossover intermittent fasting trial for 2 weeks at baseline and during the eating timeframe of 8 h (early or late in the course of the day). The FDDB app and database enabled a quicker and less sophisticated analysis of food composition and timing than the PRODI® software. Good agreement between the methods was found for energy and macronutrient intakes, while the FDDB data on most micronutrients and saturated/unsaturated fat intake were unreliable. In contrast to PRODI®, FDDB provided effective assessment of timely compliance, making it a promising tool for chrononutritional studies. Thus, the FDDB app is comparable to the traditional PRODI® dietary assessment method, and can be effectively used in human dietary trials and medical practice for specific goals.

High Protein Diets Improve Liver Fat and Insulin Sensitivity by Prandial but Not Fasting Glucagon Secretion in Type 2 Diabetes.

Glucagon (GCGN) plays a key role in glucose and amino acid (AA) metabolism by increasing hepatic glucose output. AA strongly stimulate GCGN secretion which regulates hepatic AA degradation by ureagenesis. Although increased fasting GCGN levels cause hyperglycemia GCGN has beneficial actions by stimulating hepatic lipolysis and improving insulin sensitivity through alanine induced activation of AMPK. Indeed, stimulating prandial GCGN secretion by isocaloric high protein diets (HPDs) strongly reduces intrahepatic lipids (IHLs) and improves glucose metabolism in type 2 diabetes mellitus (T2DM). Therefore, the role of GCGN and circulating AAs in metabolic improvements in 31 patients with T2DM consuming HPD was investigated. Six weeks HPD strongly coordinated GCGN and AA levels with IHL and insulin sensitivity as shown by significant correlations compared to baseline. Reduction of IHL during the intervention by 42% significantly improved insulin sensitivity [homeostatic model assessment for insulin resistance (HOMA-IR) or hyperinsulinemic euglycemic clamps] but not fasting GCGN or AA levels. By contrast, GCGN secretion in mixed meal tolerance tests (MMTTs) decreased depending on IHL reduction together with a selective reduction of GCGN-regulated alanine levels indicating greater GCGN sensitivity. HPD aligned glucose metabolism with GCGN actions. Meal stimulated, but not fasting GCGN, was related to reduced liver fat and improved insulin sensitivity. This supports the concept of GCGN-induced hepatic lipolysis and alanine- and ureagenesis-induced activation of AMPK by HPD.

Physical Performance and Non-Esterified Fatty Acids in Men and Women after Transcatheter Aortic Valve Implantation (TAVI).

BACKGROUND: Men and women with valvular heart disease have different risk profiles for clinical endpoints. Non-esterified fatty acids (NEFA) are possibly involved in cardio-metabolic disease. However, it is unclear whether NEFA concentrations are associated with physical performance in patients undergoing transcatheter aortic valve implantation (TAVI) and whether there are sex-specific effects. METHODS: To test the hypothesis that NEFA concentration is associated with sex-specific physical performance, we prospectively analysed data from one hundred adult patients undergoing TAVI. NEFA concentrations, physical performance and anthropometric parameters were measured before and 6 and 12 months after TAVI. Physical performance was determined by a six-minute walking test (6-MWT) and self-reported weekly bicycle riding time. RESULTS: Before TAVI, NEFA concentrations were higher in patients (44 women, 56 men) compared to the normal population. Median NEFA concentrations at 6 and 12 months after TAVI were within the reference range reported in the normal population in men but not women. Men but not women presented with an increased performance in the 6-MWT over time (p = 0.026, p = 0.142, respectively). Additionally, men showed an increased ability to ride a bicycle after TAVI compared to before TAVI (p = 0.034). NEFA concentrations before TAVI correlated with the 6-MWT before TAVI in women (Spearman's rho -0.552; p = 0.001) but not in men (Spearman's rho -0.007; p = 0.964). No association was found between NEFA concentrations and physical performance 6 and 12 months after TAVI. CONCLUSIONS: NEFA concentrations improved into the reference range in men but not women after TAVI. Men but not women have an increased physical performance after TAVI. No association between NEFA and physical performance was observed in men and women after TAVI.

Effects of Early vs. Late Time-Restricted Eating on Cardiometabolic Health, Inflammation, and Sleep in Overweight and Obese Women: A Study Protocol for the ChronoFast Trial.

Background: Time-restricted eating is a promising dietary strategy for weight loss, glucose and lipid metabolism improvements, and overall well-being. However, human studies demonstrated contradictory results for the restriction of food intake to the beginning (early TRE, eTRE) or to the end of the day (late TRE, lTRE) suggesting that more carefully controlled studies are needed. Objective: The aim of the ChronoFast trial study is to determine whether eTRE or lTRE is a better dietary approach to improve cardiometabolic health upon minimized calorie deficits and nearly stable body weight. Methods: Here, we present the study protocol of the randomized cross-over ChronoFast clinical trial comparing effects of 2 week eTRE (8:00 to 16:00 h) and lTRE (13:00 to 21:00 h) on insulin sensitivity and other glycemic traits, blood lipids, inflammation, and sleep quality in 30 women with overweight or obesity and increased risk of type 2 diabetes. To ensure timely compliance and unchanged dietary composition, and to minimize possible calorie deficits, real-time monitoring of dietary intake and body weight using a smartphone application, and extensive nutritional counseling are performed. Continuous glucose monitoring, oral glucose tolerance test, 24 h activity tracking, questionnaires, and gene expression analysis in adipose tissue and blood monocytes will be used for assessment of study outcomes. Discussion: The trial will determine whether eTRE or lTRE is more effective to improve cardiometabolic health, elucidate underlying mechanisms, and contribute to the development of recommendations for medical practice and the wider population. Clinical Trial Registration: www.ClinicalTrials.gov, Identifier [NCT04351672].

Time Restricted Eating: A Dietary Strategy to Prevent and Treat Metabolic Disturbances.

Time-restricted eating (TRE), a dietary approach limiting the daily eating window, has attracted increasing attention in media and research. The eating behavior in our modern society is often characterized by prolonged and erratic daily eating patterns, which might be associated with increased risk of obesity, diabetes, and cardiovascular diseases. In contrast, recent evidence suggests that TRE might support weight loss, improve cardiometabolic health, and overall wellbeing, but the data are controversial. The present work reviews how TRE affects glucose and lipid metabolism based on clinical trials published until June 2021. A range of trials demonstrated that TRE intervention lowered fasting and postprandial glucose levels in response to a standard meal or oral glucose tolerance test, as well as mean 24-h glucose and glycemic excursions assessed using continuous glucose monitoring. In addition, fasting insulin decreases and improvement of insulin sensitivity were demonstrated. These changes were often accompanied by the decrease of blood triglyceride and cholesterol levels. However, a number of studies found that TRE had either adverse or no effects on glycemic and lipid traits, which might be explained by the different study designs (i.e., fasting/eating duration, daytime of eating, changes of calorie intake, duration of intervention) and study subject cohorts (metabolic status, age, gender, chronotype, etc.). To summarize, TRE represents an attractive and easy-to-adapt dietary strategy for the prevention and therapy of glucose and lipid metabolic disturbances. However, carefully controlled future TRE studies are needed to confirm these effects to understand the underlying mechanisms and assess the applicability of personalized interventions.

Insulin Directly Regulates the Circadian Clock in Adipose Tissue.

Adipose tissue (AT) is a key metabolic organ which functions are rhythmically regulated by an endogenous circadian clock. Feeding is a "zeitgeber" aligning the clock in AT with the external time, but mechanisms of this regulation remain largely unclear. We tested the hypothesis that postprandial changes of the hormone insulin directly entrain circadian clocks in AT and investigated a transcriptional-dependent mechanism of this regulation. We analyzed gene expression in subcutaneous AT (SAT) of obese subjects collected before and after the hyperinsulinemic-euglycemic clamp or control saline infusion (SC). The expressions of core clock genes PER2, PER3, and NR1D1 in SAT were differentially changed upon insulin and saline infusion, suggesting insulin-dependent clock regulation. In human stem cell-derived adipocytes, mouse 3T3-L1 cells, and AT explants from mPer2Luc knockin mice, insulin induced a transient increase of the Per2 mRNA and protein expression, leading to the phase shift of circadian oscillations, with similar effects for Per1 Insulin effects were dependent on the region between -64 and -43 in the Per2 promoter but not on CRE and E-box elements. Our results demonstrate that insulin directly regulates circadian clocks in AT and isolated adipocytes, thus representing a primary mechanism of feeding-induced AT clock entrainment.

Hepatic Wnt1 Inducible Signaling Pathway Protein 1 (WISP-1/CCN4) Associates with Markers of Liver Fibrosis in Severe Obesity.

Liver fibrosis is a critical complication of obesity-induced fatty liver disease. Wnt1 inducible signaling pathway protein 1 (WISP1/CCN4), a novel adipokine associated with visceral obesity and insulin resistance, also contributes to lung and kidney fibrosis. The aim of the present study was to investigate the role of CCN4 in liver fibrosis in severe obesity. For this, human liver biopsies were collected from 35 severely obese humans (BMI 42.5 ± 0.7 kg/m2, age 46.7 ± 1.8 y, 25.7% males) during bariatric surgery and examined for the expression of CCN4, fibrosis, and inflammation markers. Hepatic stellate LX-2 cells were treated with human recombinant CCN4 alone or in combination with LPS or transforming growth factor beta (TGF-ß) and examined for fibrosis and inflammation markers. CCN4 mRNA expression in the liver positively correlated with BMI and expression of fibrosis markers COL1A1, COL3A1, COL6A1, αSMA, TGFB1, extracellular matrix turnover enzymes TIMP1 and MMP9, and the inflammatory marker ITGAX/CD11c. In LX-2 cells, the exposure to recombinant CCN4 caused dose-dependent induction of MMP9 and MCP1. CCN4 potentiated the TGF-ß-mediated induction of COL3A1, TIMP1, and MCP1 but showed no interaction with LPS treatment. Our results suggest a potential contribution of CCN4 to the early pathogenesis of obesity-associated liver fibrosis.

Orphan GPR116 mediates the insulin sensitizing effects of the hepatokine FNDC4 in adipose tissue.

The proper functional interaction between different tissues represents a key component in systemic metabolic control. Indeed, disruption of endocrine inter-tissue communication is a hallmark of severe metabolic dysfunction in obesity and diabetes. Here, we show that the FNDC4-GPR116, liver-white adipose tissue endocrine axis controls glucose homeostasis. We found that the liver primarily controlled the circulating levels of soluble FNDC4 (sFNDC4) and lowering of the hepatokine FNDC4 led to prediabetes in mice. Further, we identified the orphan adhesion GPCR GPR116 as a receptor of sFNDC4 in the white adipose tissue. Upon direct and high affinity binding of sFNDC4 to GPR116, sFNDC4 promoted insulin signaling and insulin-mediated glucose uptake in white adipocytes. Indeed, supplementation with FcsFNDC4 in prediabetic mice improved glucose tolerance and inflammatory markers in a white-adipocyte selective and GPR116-dependent manner. Of note, the sFNDC4-GPR116, liver-adipose tissue axis was dampened in (pre) diabetic human patients. Thus our findings will now allow for harnessing this endocrine circuit for alternative therapeutic strategies in obesity-related pre-diabetes.

Liver fat scores do not reflect interventional changes in liver fat content induced by high-protein diets.

Non-alcoholic fatty liver disease (NAFLD) is common in Metabolic Syndrome and type 2 diabetes (T2DM), driven by energy imbalance, saturated fats and simple carbohydrates. NAFLD requires screening and monitoring for late complications. Liver fat indices may predict NAFLD avoiding expensive or invasive gold-standard methods, but they are poorly validated for use in interventional settings. Recent data indicate a particular insensitivity to weight-independent liver fat reduction. We evaluated 31 T2DM patients, completing a randomized intervention study on isocaloric high-protein diets. We assessed anthropometric measures, intrahepatic lipid (IHL) content and serum liver enzymes, allowing AUROC calculations as well as cross-sectional and longitudinal Spearman correlations between the fatty liver index, the NAFLD-liver fat score, the Hepatosteatosis Index, and IHL. At baseline, all indices predicted NAFLD with moderate accuracy (AUROC 0.731-0.770), supported by correlation analyses. Diet-induced IHL changes weakly correlated with changes of waist circumference, but no other index component or the indices themselves. Liver fat indices may help to easily detect NAFLD, allowing cost-effective allocation of further diagnostics to patients at high risk. IHL reduction by weight-independent diets is not reflected by a proportional change in liver fat scores. Further research on the development of treatment-sensitive indices is required.Trial registration: The trial was registered at clinicaltrials.gov: NCT02402985.

Effects of High and Low Protein Diets on Inflammatory Profiles in People with Morbid Obesity: A 3-Week Intervention Study.

Nutritional interventions in morbidly obese individuals that effectively reverse a pro-inflammatory state and prevent obesity-associated medical complications are highly warranted. Our aim was to evaluate the effect of high (HP) or low (LP) protein diets on circulating immune-inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1), chemerin, omentin, leptin, total adiponectin, high molecular weight adiponectin, and fetuin-A. With this aim, 18 people with morbid obesity were matched into two hypocaloric groups: HP (30E% protein, n = 8) and LP (10E% protein, n = 10) for three weeks. Biomarkers were measured pre and post intervention and linear mixed-effects models were used to investigate differences. Consuming HP or LP diets resulted in reduced CRP (HP: -2.2 ± 1.0 mg/L, LP: -2.3 ± 0.9 mg/L) and chemerin (HP: -17.9 ± 8.6 ng/mL, LP: -20.0 ± 7.4 ng/mL), with no statistically significant differences by diet arm. Participants following the LP diet showed a more pronounced decrease in leptin (-19.2 ± 6.0 ng/mL) and IL-6 (-0.4 ± 0.1 pg/mL) and an increase in total adiponectin (1.6 ± 0.6 µg/mL). Changes were also observed for the remaining biomarkers to a smaller degree by the HP than the LP hypocaloric diet, suggesting that a LP hypocaloric diet modulates a wider range of immune inflammatory biomarkers in morbidly obese individuals.

High-protein diet more effectively reduces hepatic fat than low-protein diet despite lower autophagy and FGF21 levels.

BACKGROUND AND AIMS: Non-alcoholic fatty liver disease (NAFLD) is becoming increasingly prevalent and nutrition intervention remains the most important therapeutic approach for NAFLD. Our aim was to investigate whether low- (LP) or high-protein (HP) diets are more effective in reducing liver fat and reversing NAFLD and which mechanisms are involved. METHODS: 19 participants with morbid obesity undergoing bariatric surgery were randomized into two hypocaloric (1500-1600 kcal/day) diet groups, a low protein (10E% protein) and a high protein (30E% protein), for three weeks prior to surgery. Intrahepatic lipid levels (IHL) and serum fibroblast growth factor 21 (FGF21) were measured before and after the dietary intervention. Autophagy flux, histology, mitochondrial activity and gene expression analyses were performed in liver samples collected during surgery. RESULTS: IHL levels decreased by 42.6% in the HP group, but were not significantly changed in the LP group despite similar weight loss. Hepatic autophagy flux and serum FGF21 increased by 66.7% and 42.2%, respectively, after 3 weeks in the LP group only. Expression levels of fat uptake and lipid biosynthesis genes were lower in the HP group compared with those in the LP group. RNA-seq analysis revealed lower activity of inflammatory pathways upon HP diet. Hepatic mitochondrial activity and expression of ß-oxidation genes did not increase in the HP group. CONCLUSIONS: HP diet more effectively reduces hepatic fat than LP diet despite of lower autophagy and FGF21. Our data suggest that liver fat reduction upon HP diets result primarily from suppression of fat uptake and lipid biosynthesis.