Lipolytic catecholamine resistance linked to alpha 2-adrenoceptor sensitivity--a metabolic predictor of weight loss in obese subjects

Objective: The weight loss achieved during treatment with very-low-calorie diets (VLCD) varies between individuals. The aim of this study was to investigate whether interindividual variations in catecholamine-induced lipolysis are of importance for the rate of weight loss during VLCD.

Design: Prospective study.

Subjects: Twenty-eight obese, but otherwise healthy and drug-free women aged 20-57 y with BMI 33.3-47.5 kg/m2 were investigated before entering a four week weight reduction program with a calorie-restricted diet.

Measurements: A subcutaneous adipose tissue biopsy was obtained from the abdominal area. Isolated fat cells were prepared and incubated in vitro with agents acting on lipolysis at defined steps in the lipolytic cascade. Glycerol release was measured and used as a lipolytic index. Following the biopsy, the subjects underwent a four week VLCD treatment.

Results: The decrease in body weight in the whole group ranged between 4.8 and 13.5 kg. Dietary compliance was ascertained by daily measurements of urine-ketones and regular interviews and was satisfactory in all subjects throughout the study. Based on percent body weight reduction, the material was divided into two equally sized groups, classified as rapid or slow weight losers. The rapid weight losers were 10-fold more sensitive to the lipolytic effect of noradrenaline (P = 0.04) and 10-fold less sensitive (P = 0.002) to the antilipolytic effect induced by the alpha 2-adrenoceptor agonist clonidine than the slow weight losers. In the whole material, weight loss was significantly correlated (adjusted r2 = 0.25) with alpha 2-adrenoceptor sensitivity.

Conclusion: Rapid weight loss during VLCD is associated with increased adipocyte lipolytic sensitivity to catecholamines due to decreased alpha 2-adrenoceptor sensitivity, which in turn may promote lipid mobilization. It appears that variations in alpha 2-adrenoceptor sensitivity in adipocytes may be predictive of weight loss during VLCD.

Fat burners: nutrition supplements that increase fat metabolism

Summary

The term ‘fat burner’ is used to describe nutrition supplements that are claimed to acutely increase fat metabolism or energy expenditure, impair fat absorption, increase weight loss, increase fat oxidation during exercise, or somehow cause long-term adaptations that promote fat metabolism. Often, these supplements contain a number of ingredients, each with its own proposed mechanism of action and it is often claimed that the combination of these substances will have additive effects. The list of supplements that are claimed to increase or improve fat metabolism is long; the most popular supplements include caffeine, carnitine, green tea, conjugated linoleic acid, forskolin, chromium, kelp and fucoxanthin. In this review the evidence for some of these supplements is briefly summarized. Based on the available literature, caffeine and green tea have data to back up its fat metabolism-enhancing properties. For many other supplements, although some show some promise, evidence is lacking. The list of supplements is industry-driven and is likely to grow at a rate that is not matched by a similar increase in scientific underpinning.

Choline Intake Correlates with Cognitive Performance among Elder Adults in the United States

Objective: This research attempted to explore the neuroprotective effect of choline and establish evidence for future dietary recommendations and nutritional interventions to maintain a proper cognitive function among elders aged >60 years in the US.

Method: This cross-sectional study retrieved data of 2,393 eligible elderly participants from the 2011-2014 National Health and Nutrition Examination Survey. Combining dietary and supplement choline intake, total choline intake was evaluated using the 24-hour dietary recall method and the dietary supplement questionnaire. Total choline intake was categorized into tertiles, which ranged at <187.60 mg/day (T1), 187.60-399.50 mg/day (T2), and >399.50 mg/day (T3). The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning subtest, Animal Fluency (AF) test, and Digit Symbol Substitution test (DSST) was used to measure cognitive function. Participants who scored the lowest 25th percentile in each cognitive test were classified in the low cognitive function (LC) group. Logistic regression models were implemented to examine the association between total choline intake and the incidence of LC.

Results: In the CERAD test, the risk of LC was significantly lower in T2 than T1 (OR: 0.668, 95% CI: 0.493-0.904, and P = 0.006) when adjusted for age, gender, BMI, alcohol consumption, and hypertension. Similarly, T2 was associated with a significantly lower risk of LC when assessed by the AF test (OR: 0.606, 95% CI: 0.580-0.724, and P < 0.001) and DSST (0.584, 95% CI: 0.515-0.661, and P < 0.001). In all three cognitive measures, the T3 of the total choline intake was not associated with cognitive function compared to T1.

Conclusion: Total choline intake at 187.06-399.50 mg/day reduces the risk of LC by approximately 50% compared to intake at <187.6 mg/day. The findings of this research may be used to establish dietary recommendations and nutritional interventions to optimize the cognitive function among elders.

A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations

Background: Ad libitum, low-carbohydrate diets decrease caloric intake and cause weight loss. It is unclear whether these effects are due to the reduced carbohydrate content of such diets or to their associated increase in protein intake.

Objective: We tested the hypothesis that increasing the protein content while maintaining the carbohydrate content of the diet lowers body weight by decreasing appetite and spontaneous caloric intake.

Design: Appetite, caloric intake, body weight, and fat mass were measured in 19 subjects placed sequentially on the following diets: a weight-maintaining diet (15% protein, 35% fat, and 50% carbohydrate) for 2 wk, an isocaloric diet (30% protein, 20% fat, and 50% carbohydrate) for 2 wk, and an ad libitum diet (30% protein, 20% fat, and 50% carbohydrate) for 12 wk. Blood was sampled frequently at the end of each diet phase to measure the area under the plasma concentration versus time curve (AUC) for insulin, leptin, and ghrelin.

Results: Satiety was markedly increased with the isocaloric high-protein diet despite an unchanged leptin AUC. Mean (+/-SE) spontaneous energy intake decreased by 441 +/- 63 kcal/d, body weight decreased by 4.9 +/- 0.5 kg, and fat mass decreased by 3.7 +/- 0.4 kg with the ad libitum, high-protein diet, despite a significantly decreased leptin AUC and increased ghrelin AUC.

Conclusions: An increase in dietary protein from 15% to 30% of energy at a constant carbohydrate intake produces a sustained decrease in ad libitum caloric intake that may be mediated by increased central nervous system leptin sensitivity and results in significant weight loss. This anorexic effect of protein may contribute to the weight loss produced by low-carbohydrate diets.

The effect of apple cider vinegar on lipid profiles and glycemic parameters: a systematic review and meta-analysis of randomized clinical trials

Background

Elevated lipid profiles and impaired glucose homeostasis are risk factors for several cardiovascular diseases (CVDs), which, subsequently, represent a leading cause of early mortality, worldwide. The aim of the current study was to conduct a systematic review and meta-analysis of the effect of apple cider vinegar (ACV) on lipid profiles and glycemic parameters in adults.

Methods

A systematic search was conducted in electronic databases, including Medline, Scopus, Cochrane Library, and Web of Knowledge, from database inception to January 2020. All clinical trials which investigated the effect of ACV on lipid profiles and glycemic indicators were included. Studies were excluded if ACV was used in combination with other interventions or when the duration of intervention was < 2 weeks. To account for between-study heterogeneity, we performed meta-analysis using a random-effects model.

Results

Overall, nine studies, including 10 study arms, were included in this meta-analysis. We found that ACV consumption significantly decreased serum total cholesterol (− 6.06 mg/dL; 95% CI: − 10.95, − 1.17; I2: 39%), fasting plasma glucose (− 7.97 mg/dL; 95% CI: − 13.74, − 2.21; I2: 75%), and HbA1C concentrations (− 0.50; 95% CI: − 0.90, − 0.09; I2: 91%). No significant effect of ACV consumption was found on serum LDL-C, HDL-C, fasting insulin concentrations, or HOMA-IR. The stratified analysis revealed a significant reduction of serum TC and TG in a subgroup of patients with type 2 diabetes, those who took ≤15 mL/day of ACV, and those who consumed ACV for > 8-weeks, respectively. Furthermore, ACV consumption significantly decreased FPG levels in a subgroup of studies that administered ACV for > 8-weeks. Further, ACV intake appeared to elicit an increase in FPG and HDL-C concentrations in apparently healthy participants.

Conclusion

We found a significant favorable effect of ACV consumption on FPG and blood lipid levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03351-w.

Keywords:Apple cider vinegar, Lipid profiles, Clinical trials, Meta-analysis, Glycemic indices