Concept: Adipose tissue
Carbohydrate staples such as pasta have been implicated in the obesity epidemic. It is unclear whether pasta contributes to weight gain or like other low-glycaemic index (GI) foods contributes to weight loss. We synthesised the evidence of the effect of pasta on measures of adiposity.
Chronic cortisol exposure is hypothesized to contribute to obesity. This study examined associations between hair cortisol concentrations, a novel indicator of long-term cortisol exposure, and adiposity in a large population-based sample.
Weight discrimination is prevalent in American society. Although associated consistently with psychological and economic outcomes, less is known about whether weight discrimination is associated with longitudinal changes in obesity. The objectives of this research are (1) to test whether weight discrimination is associated with risk of becoming obese (Body Mass Index≥30; BMI) by follow-up among those not obese at baseline, and (2) to test whether weight discrimination is associated with risk of remaining obese at follow-up among those already obese at baseline. Participants were drawn from the Health and Retirement Study, a nationally representative longitudinal survey of community-dwelling US residents. A total of 6,157 participants (58.6% female) completed the discrimination measure and had weight and height available from the 2006 and 2010 assessments. Participants who experienced weight discrimination were approximately 2.5 times more likely to become obese by follow-up (OR = 2.54, 95% CI = 1.58-4.08) and participants who were obese at baseline were three times more likely to remain obese at follow up (OR = 3.20, 95% CI = 2.06-4.97) than those who had not experienced such discrimination. These effects held when controlling for demographic factors (age, sex, ethnicity, education) and when baseline BMI was included as a covariate. These effects were also specific to weight discrimination; other forms of discrimination (e.g., sex, race) were unrelated to risk of obesity at follow-up. The present research demonstrates that, in addition to poorer mental health outcomes, weight discrimination has implications for obesity. Rather than motivating individuals to lose weight, weight discrimination increases risk for obesity.
Brown adipose tissue (BAT) has attracted considerable research interest because of its therapeutic potential to treat obesity and associated metabolic diseases. Augmentation of brown fat mass and/or its function may represent an attractive strategy to enhance energy expenditure. Using high-throughput phenotypic screening to induce brown adipocyte reprogramming in committed myoblasts, we identified a retinoid X receptor (RXR) agonist, bexarotene (Bex), that efficiently converted myoblasts into brown adipocyte-like cells. Bex-treated mice exhibited enlarged BAT mass, enhanced BAT function, and a modest browning effect in subcutaneous white adipose tissue (WAT). Expression analysis showed that Bex initiated several “browning” pathways at an early stage during brown adipocyte reprogramming. Our findings suggest RXRs as new master regulators that control brown and beige fat development and activation, unlike the common adipogenic regulator PPARγ. Moreover, we demonstrated that selective RXR activation may potentially offer a therapeutic approach to manipulate brown/beige fat function in vivo.
Weight loss maintenance remains a major challenge in obesity treatment.
High-protein (HP) intake during weight loss (WL) therapy is often recommended because it reduces the loss of lean tissue mass. However, HP intake could have adverse effects on metabolic function, because protein ingestion reduces postprandial insulin sensitivity. In this study, we compared the effects of ∼10% WL with a hypocaloric diet containing 0.8 g protein/kg/day and a hypocaloric diet containing 1.2 g protein/kg/day on muscle insulin action in postmenopausal women with obesity. We found that HP intake reduced the WL-induced decline in lean tissue mass by ∼45%. However, HP intake also prevented the WL-induced improvements in muscle insulin signaling and insulin-stimulated glucose uptake, as well as the WL-induced adaptations in oxidative stress and cell structural biology pathways. Our data demonstrate that the protein content of a WL diet can have profound effects on metabolic function and underscore the importance of considering dietary macronutrient composition during WL therapy for people with obesity.
There are substantial differences in the distribution of adipose tissue between women and men. We assessed the sex-specific relationships and their differences between measures of general and central adiposity and the risk of incident myocardial infarction (MI).
Subcutaneous white adipose tissue (scWAT) is the major fat depot in humans and is a central player in regulating whole body metabolism. Skin exposure to UV wavelengths from sunlight is required for Vitamin D synthesis and pigmentation, although it is plausible that longer visible wavelengths that penetrate the skin may regulate scWAT function. In this regard, we discovered a novel blue light-sensitive current in human scWAT that is mediated by melanopsin coupled to transient receptor potential canonical cation channels. This pathway is activated at physiological intensities of light that penetrate the skin on a sunny day. Daily exposure of differentiated adipocytes to blue light resulted in decreased lipid droplet size, increased basal lipolytic rate and alterations in adiponectin and leptin secretion. Our results suggest that scWAT function may be directly under the influence of ambient sunlight exposure and may have important implications for our current understanding of adipocyte biology. (150 words).
Obesity, typically quantified in terms of Body Mass Index (BMI) exceeding threshold values, is considered a leading cause of premature death worldwide. For given body size (BMI), it is recognized that risk is also affected by body shape, particularly as a marker of abdominal fat deposits. Waist circumference (WC) is used as a risk indicator supplementary to BMI, but the high correlation of WC with BMI makes it hard to isolate the added value of WC.
A discrepancy exists with regard to the effect of smartphone applications (apps) on weight reduction due to the several limitations of previous studies. This is a retrospective cohort study, aimed to investigate the effectiveness of a smartphone app on weight reduction in obese or overweight individuals, based on the complete enumeration study that utilized the clinical and logging data entered by Noom Coach app users between October 2012 and April 2014. A total of 35,921 participants were included in the analysis, of whom 77.9% reported a decrease in body weight while they were using the app (median 267 days; interquartile range = 182). Dinner input frequency was the most important factor for successful weight loss (OR = 10.69; 95% CI = 6.20-19.53; p < 0.001), and more frequent input of weight significantly decreased the possibility of experiencing the yo-yo effect (OR = 0.59, 95% CI = 0.39-0.89; p < 0.001). This study demonstrated the clinical utility of an app for successful weight reduction in the majority of the app users; the effects were more significant for individuals who monitored their weight and diet more frequently.