body weight
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Post-diagnosis changes in body composition and renal cell cancer survival
ABSTRACT Significance. Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer and most lethal subtype, and there is great interest in the identification of potentially modifiable prognostic factors. Although weight status seems to be relevant, the relationship between body mass index (BMI) at diagnosis and survival among ccRCC patients indicates that mortality is lowest among those classified as overweight or obese at the time of diagnosis by BMI. This has resulted in confusion in clinical guidance for weight management among ccRCC patients. Recent work involving body composition features (adipose and muscle tissue) has provided some insight, but we do not understand how weight or body composition changes after diagnosis relate to survival, nor how these changes relate to pathological and molecular tumor features— information which is needed to resolve this controversy. Rigorous analytical approaches are further required to accurately address these questions. Innovation. Our study is highly innovative in that 1) we will be the first to leverage a large-scale cohort of ccRCC patients with multiple assessments of weight and body composition from diagnosis onward; 2) we will examine tumor characteristics, including molecular features, as potential drivers of these changes; and 3) we will use a rigorous joint modeling approach to simultaneously model the post-diagnosis trajectories of weight and body composition and their relationships with cancer outcomes in the most statistically sound manner. Our findings will inform clinical management of, and identify modifiable body composition features to improve survival for the growing number of ccRCC patients. Approach. We will use available data from the RESOLVE cohort, an NCI-funded retrospective cohort of 1,239 Stage I-III clear-cell renal cell carcinoma (ccRCC) patients diagnosed between 2000-2020 at Memorial Sloan Kettering Cancer Center. These data include clinical and patient-level factors collected from the medical record, including repeated height and weight assessments, body composition measures from existing computed tomography scans, pathological and molecular tumor characteristics, and overall survival (OS) and disease-free survival (DFS). We will use a joint modeling approach to simultaneously model changes in post-diagnosis body weight (Aim 1) and OS and DFS, as well as post-diagnosis changes in muscle and adipose tissue features (Aim 2) and OS and DFS. Models will include molecular tumor characteristics as predictors of these longitudinal trajectories. Impact. These results will provide crucial insight into the relationship between body composition changes and outcomes among ccRCC patients, and potentially identify tumor-related characteristics driving these associations. These results will resolve apparent paradoxes around the relationship between obesity and ccRCC mortality and identify potential targets for nutrition and physical activity interventions on body composition.
Obesity and Brain – Bidirectional Influences
The regulation of body weight relies on homeostatic mechanisms that use a combination of internal signals and external cues to initiate and terminate food intake. Homeostasis depends on intricate communication between the body and the hypothalamus involving numerous neural and hormonal signals. However, there is growing evidence that higher-level cognitive function may also influence energy balance. For instance, research has shown that BMI is consistently linked to various brain, cognitive, and personality measures, implicating executive, reward, and attentional systems. Moreover, the rise in obesity rates over the past half-century is attributed to the affordability and widespread availability of highly processed foods, a phenomenon that contradicts the idea that food intake is solely regulated by homeostasis. I will suggest that prefrontal systems involved in value computation and motivation act to limit food overconsumption when food is scarce or expensive, but promote over-eating when food is abundant, an optimum strategy from an economic standpoint. I will review the genetic and neuroscience literature on the CNS control of body weight. I will present recent studies supporting a role of prefrontal systems in weight control. I will also present contradictory evidence showing that frontal executive and cognitive findings in obesity may be a consequence not a cause of increased hunger. Finally I will review the effects of obesity on brain anatomy and function. Chronic adiposity leads to cerebrovascular dysfunction, cortical thinning, and cognitive impairment. As the most common preventable risk factor for dementia, obesity poses a significant threat to brain health. I will conclude by reviewing evidence for treatment of obesity in adults to prevent brain disease.
Uncovering the molecular effectors of diet and exercise
Despite the profound effects of nutrition and physical activity on human health, our understanding of the molecules mediating the salutary effects of specific foods or activities remains remarkably limited. Here, we share our ongoing studies that use unbiased and high-resolution metabolomics technologies to uncover the molecules and molecular effectors of diet and exercise. We describe how exercise stimulates the production of Lac-Phe, a blood-borne signaling metabolite that suppresses feeding and obesity. Ablation of Lac-Phe biosynthesis in mice increases food intake and obesity after exercise. We also describe the discovery of an orphan metabolite, BHB-Phe. Ketosis-inducible BHB-Phe is a congener of exercise-inducible Lac-Phe, produced in CNDP2+ cells when levels of BHB are high, and functions to lower body weight and adiposity in ketosis. Our data uncover an unexpected and underappreciated signaling role for metabolic fuel derivatives in mediating the cardiometabolic benefits of diet and exercise. These data also suggest that diet and exercise may mediate their physiologic effects on energy balance via a common family of molecules and overlapping signaling pathways.
Western diet consumption and memory impairment: what, when, and how?
Habitual consumption of a “Western diet”, containing higher than recommended levels of simple sugars and saturated fatty acids, is associated with cognitive impairments in humans and in various experimental animal models. Emerging findings reveal that the specific mnemonic processes that are disrupted by Western diet consumption are those that rely on the hippocampus, a brain region classically linked with memory control and more recently with the higher-order control of food intake. Our laboratory has established rat models in which excessive consumption of different components of a Western diet during the juvenile and adolescent periods of development yields long-term impairments in hippocampal-dependent memory function without concomitant increases in total caloric intake, body weight, or adiposity. Our ongoing work is investigating alterations in the gut microbiome as a potential underlying neurobiological mechanism linking early life unhealthy dietary factors to adverse neurocognitive outcomes.
Targeting the brain to improve obesity and type 2 diabetes
The increasing prevalence of obesity and type 2 diabetes (T2D) and associated morbidity and mortality emphasizes the need for a more complete understanding of the mechanisms mediating energy homeostasis to accelerate the identification of new medications. Recent reports indicate that obesity medication, 5-hydroxytryptamine (5-HT, serotonin)2C receptor (5-HT2CR) agonist lorcaserin improves glycemic control in association with weight loss in obese patients with T2D. We examined whether lorcaserin has a direct effect on insulin sensitivity and how this effect is achieved. We clarify that lorcaserin dose-dependently improves glycemic control in a mouse model of T2D without altering body weight. Examining the mechanism of this effect, we reveal a necessary and sufficient neurochemical mediator of lorcaserin’s glucoregulatory effects, via activation of brain pro-opiomelanocortin (POMC) peptides. We observed that lorcaserin reduces hepatic glucose production and improves insulin sensitivity. These data suggest that lorcaserin’s action within the brain represents a mechanistically novel treatment for T2D: findings of significance to a prevalent global disease.
Central representations of protein availability regulating appetite and body weight control
Dietary protein quantity and quality greatly impact metabolic health via evolutionary-conserved mechanisms that ensure avoidance of amino acid imbalanced food sources, promote hyperphagia when dietary protein density is low, and conversely produce satiety when dietary protein density is high. Growing evidence support the emerging concept of protein homeostasis in mammals, where protein intake is maintained within a tight range independently of energy intake to reach a target protein intake. The behavioural and neuroendocrine mechanisms underlying these adaptations are unclear and form the focus of our research.
Impairment of AgRP neurons influences body weight, lifespan, and behavior in calorie-restricted mice
FENS Forum 2024
Role of the dorsal vagal complex in semaglutide-induced reduction of food intake and body weight
FENS Forum 2024
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