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Motivation to eat and not to eat - The psycho-biological conflict in anorexia nervosa.
Frank, GKW, DeGuzman, MC, Shott, ME
Physiology & behavior. 2019;:185-190
Abstract
Anorexia nervosa is a severe psychiatric illness with high mortality. Brain imaging research has indicated altered reward circuits in the disorder. Here we propose a disease model for anorexia nervosa, supported by recent studies, that integrates psychological and biological factors. In that model, we propose that there is a conflict between the conscious motivation to restrict food, and a body-homeostasis driven motivation to approach food in response to weight loss. These opposing motivations trigger anxiety, which maintains the vicious cycle of ongoing energy restriction and weight loss.
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Gastrointestinal Sensing of Meal-Related Signals in Humans, and Dysregulations in Eating-Related Disorders.
Hajishafiee, M, Bitarafan, V, Feinle-Bisset, C
Nutrients. 2019;(6)
Abstract
The upper gastrointestinal (GI) tract plays a critical role in sensing the arrival of a meal, including its volume as well as nutrient and non-nutrient contents. The presence of the meal in the stomach generates a mechanical distension signal, and, as gastric emptying progresses, nutrients increasingly interact with receptors on enteroendocrine cells, triggering the release of gut hormones, with lipid and protein being particularly potent. Collectively, these signals are transmitted to the brain to regulate appetite and energy intake, or in a feedback loop relayed back to the upper GI tract to further adjust GI functions, including gastric emptying. The research in this area to date has provided important insights into how sensing of intraluminal meal-related stimuli acutely regulates appetite and energy intake in humans. However, disturbances in the detection of these stimuli have been described in a number of eating-related disorders. This paper will review the GI sensing of meal-related stimuli and the relationship with appetite and energy intake, and examine changes in GI responses to luminal stimuli in obesity, functional dyspepsia and anorexia of ageing, as examples of eating-related disorders. A much better understanding of the mechanisms underlying these dysregulations is still required to assist in the development of effective management and treatment strategies in the future.
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3.
Loss-of-Control Eating and Obesity Among Children and Adolescents.
Byrne, ME, LeMay-Russell, S, Tanofsky-Kraff, M
Current obesity reports. 2019;(1):33-42
Abstract
PURPOSE OF REVIEW This review summarizes findings on pediatric loss-of-control (LOC) eating and obesity published since 2013 in relation to physiological, socioenvironmental, and psychological factors. RECENT FINDINGS LOC eating and obesity are highly comorbid in youth. Genetic and physiological risk factors are associated with the development of LOC eating. Adverse physiological outcomes of LOC eating include increased risk for overweight and obesity and greater dysfunction in components of metabolic syndrome. Socioenvironmental, psychological, and behavioral factors, such as weight-based teasing, dieting, negative affect, emotion dysregulation, and aspects of cognitive functioning, are consistently related to LOC eating in youth, independent of weight. Prospectively, LOC eating may predict the onset of anxiety disorders, depression, and more severe eating psychopathology later in life. Updates on interventions and future directions are discussed. LOC eating may be a key symptom to target adverse physiological and psychological outcomes; however, treatments are limited and require further examination.
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4.
[Implicit Self-Regulation of Food-Intake: Consequences for Psychotherapy].
Paslakis, G, de Zwaan, M
Psychotherapie, Psychosomatik, medizinische Psychologie. 2019;(11):453-461
Abstract
Explicit processes of self-regulation require insight and control during implementation and are therefore often experienced as being strenuous, while implicit processes of steering behavior are automatic, rapid and effortless. However, self-regulation is not always either explicit or implicit; all variants ranging from those that are entirely automatic to those being entirely under control are present. As individuals are not aware of their underlying implicit modes of self-regulation, it is necessary to create an approach that is proximal to affective processing, by-passing the cognitive, verbal level. Promising approaches of this kind are such including embodied experiences or such shifting the body to a state, in which the apperception of implicit mechanisms is facilitated. Given that therapeutic work of self-regulation is in many cases carried out on an explicit level of processing, the need for novel, neurobiologically founded strategies intervening on the implicit (pre-verbal) level are called for. Correspondent paradigms, e. g. the approach-avoidance task (AAT) for the assessment of implicit processes are presented here with regard to food-intake regulation. This work is a narrative (qualitative) review aiming at illustrating the field of implicit bias research as well as the development of new implicit bias training paradigms to be used as add-on in future psychotherapeutic treatments. Therefore, a selection of relevant studies based on subjective criteria was made. Thus, this work is not a systematic review and does not claim to be an exhaustive description of studies of this kind.
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Brain Stimulation to Modulate Food Intake and Eating Behavior.
Dendy, R, Stinson, EJ, Guerithault, N, Gluck, ME
Current diabetes reports. 2019;(12):152
Abstract
PURPOSE OF REVIEW Appetitive behaviors are mediated through homeostatic and reward signaling of brain circuits. There has been increasing interest in the use of neuromodulation techniques aimed at targeting brain regions such as the lateral prefrontal and subcortical regions associated with dysregulation of eating behaviors. RECENT FINDINGS Invasive brain stimulation techniques have demonstrated promising results in treating severe and enduring anorexia nervosa and morbid obesity. In addition, non-invasive techniques have been shown to successfully reduce food craving, hunger ratings, and calorie intake as well as binge/purge symptoms in eating disorders. Brain stimulation offers promising results for treating symptoms associated with eating disorders and modifying appetitive behaviors including craving and caloric consumption. Future research should focus on identifying optimal frequency and duration of stimulation and employ longitudinal studies to assess long-term effectiveness on clinical outcomes such as eating disorder symptomatology, weight loss, and sustained improvements in eating behaviors over time.
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6.
Fructose co-ingestion to increase carbohydrate availability in athletes.
Fuchs, CJ, Gonzalez, JT, van Loon, LJC
The Journal of physiology. 2019;(14):3549-3560
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Abstract
Carbohydrate availability is important to maximize endurance performance during prolonged bouts of moderate- to high-intensity exercise as well as for acute post-exercise recovery. The primary form of carbohydrates that are typically ingested during and after exercise are glucose (polymers). However, intestinal glucose absorption can be limited by the capacity of the intestinal glucose transport system (SGLT1). Intestinal fructose uptake is not regulated by the same transport system, as it largely depends on GLUT5 as opposed to SGLT1 transporters. Combining the intake of glucose plus fructose can further increase total exogenous carbohydrate availability and, as such, allow higher exogenous carbohydrate oxidation rates. Ingesting a mixture of both glucose and fructose can improve endurance exercise performance compared to equivalent amounts of glucose (polymers) only. Fructose co-ingestion can also accelerate post-exercise (liver) glycogen repletion rates, which may be relevant when rapid (<24 h) recovery is required. Furthermore, fructose co-ingestion can lower gastrointestinal distress when relatively large amounts of carbohydrate (>1.2 g/kg/h) are ingested during post-exercise recovery. In conclusion, combined ingestion of fructose with glucose may be preferred over the ingestion of glucose (polymers) only to help trained athletes maximize endurance performance during prolonged moderate- to high-intensity exercise sessions and accelerate post-exercise (liver) glycogen repletion.
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Effects of acute oral feeding on protein metabolism and muscle protein synthesis in individuals with cancer.
van der Meij, BS, De Groot, LM, Deutz, NEP, Engelen, MPKJ
Nutrition (Burbank, Los Angeles County, Calif.). 2019;:110531
Abstract
Weight loss and muscle loss are common in individuals living with cancer, with ≤50% experiencing involuntary weight loss at any time point in their cancer journey, and between 11% and 74% having sarcopenia or significant muscle loss. These changes in body composition are related to poor outcomes such as increased treatment toxicity, impaired quality of life, and reduced survival duration. Poor outcomes are not restricted to those who are underweight with severe weight loss; sarcopenia alone has been shown to be a prognostic marker across all body mass index categories, ranging from underweight to obesity To understand the mechanism of nutrition interventions in cancer and to develop effective future interventions, it is necessary to look at the acute effects of feeding on the response of the body and the ability to reach an anabolic response. The aim of this study was to explore and summarize the emerging evidence on metabolic effects of acute oral interventions on whole body protein kinetics and muscle protein synthesis in individuals with cancer.
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Dietary Patterns, Skeletal Muscle Health, and Sarcopenia in Older Adults.
Granic, A, Sayer, AA, Robinson, SM
Nutrients. 2019;(4)
Abstract
In recent decades, the significance of diet and dietary patterns (DPs) for skeletal muscle health has been gaining attention in ageing and nutritional research. Sarcopenia, a muscle disease characterised by low muscle strength, mass, and function is associated with an increased risk of functional decline, frailty, hospitalization, and death. The prevalence of sarcopenia increases with age and leads to high personal, social, and economic costs. Finding adequate nutritional measures to maintain muscle health, preserve function, and independence for the growing population of older adults would have important scientific and societal implications. Two main approaches have been employed to study the role of diet/DPs as a modifiable lifestyle factor in sarcopenia. An a priori or hypothesis-driven approach examines the adherence to pre-defined dietary indices such as the Mediterranean diet (MED) and Healthy Eating Index (HEI)-measures of diet quality-in relation to muscle health outcomes. A posteriori or data-driven approaches have used statistical tools-dimension reduction methods or clustering-to study DP-muscle health relationships. Both approaches recognise the importance of the whole diet and potential cumulative, synergistic, and antagonistic effects of foods and nutrients on ageing muscle. In this review, we have aimed to (i) summarise nutritional epidemiology evidence from four recent systematic reviews with updates from new primary studies about the role of DPs in muscle health, sarcopenia, and its components; (ii) hypothesise about the potential mechanisms of 'myoprotective' diets, with the MED as an example, and (iii) discuss the challenges facing nutritional epidemiology to produce the higher level evidence needed to understand the relationships between whole diets and healthy muscle ageing.
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Syncing Exercise With Meals and Circadian Clocks.
Heden, TD, Kanaley, JA
Exercise and sport sciences reviews. 2019;(1):22-28
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Abstract
Circadian rhythms, meals, and exercise modulate energy metabolism. This review explores the novel hypothesis that there is an optimal time of day to exercise to improve 24 h glycemia and lipemia in individuals with type 2 diabetes.
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Is exercise best served on an empty stomach?
Wallis, GA, Gonzalez, JT
The Proceedings of the Nutrition Society. 2019;(1):110-117
Abstract
The objective of this review paper is to evaluate the impact of undertaking aerobic exercise in the overnight-fasted v. fed-state, in the context of optimising the health benefits of regular physical activity. Conducting a single bout of aerobic exercise in the overnight-fasted v. fed-state can differentially modulate the aspects of metabolism and energy balance behaviours. This includes, but is not limited to, increased utilisation of fat as a fuel source, improved plasma lipid profiles, enhanced activation of molecular signalling pathways related to fuel metabolism in skeletal muscle and adipose tissue, and reductions in energy intake over the course of a day. The impact of a single bout of overnight-fasted v. fed-state exercise on short-term glycaemic control is variable, being affected by the experimental conditions, the time frame of measurement and possibly the subject population studied. The health response to undertaking overnight-fasted v. fed-state exercise for a sustained period of time in the form of exercise training is less clear, due to a limited number of studies. From the extant literature, there is evidence that overnight-fasted exercise in young, healthy men can enhance training-induced adaptations in skeletal muscle metabolic profile, and mitigate against the negative consequences of short-term excess energy intake on glucose tolerance compared with exercising in the fed-state. Nonetheless, further long-term studies are required, particularly in populations at-risk or living with cardio-metabolic disease to elucidate if feeding status prior to exercise modulates metabolism or energy balance behaviours to an extent that could impact upon the health or therapeutic benefits of exercise.