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Effect of Calorie Restriction and Intermittent Fasting Regimens on Brain-Derived Neurotrophic Factor Levels and Cognitive Function in Humans: A Systematic Review.
Alkurd, R, Mahrous, L, Zeb, F, Khan, MA, Alhaj, H, Khraiwesh, HM, Faris, ME
Medicina (Kaunas, Lithuania). 2024;60(1)
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Brain-derived neurotrophic factor (BDNF) is a protein that plays a crucial role in brain development, cognition and metabolism. Intermittent fasting (IF) is a promising therapeutic strategy for managing metabolic disorders and improving cognitive function. Therefore, this systematic review of sixteen experimental and observational studies investigated the effect of IF on BDNF production and improvements in cognition through the BDNF pathway in healthy adults and people with metabolic disorders. Included studies focused on different IF regimens such as calorie restriction (CR), alternate-day fasting (ADF), time-restricted eating (TRE) and Ramadan model of intermittent fasting (RIF) Future, well-controlled, long-term, robust studies are required to assess the effect of different IF regimens on the production of BDNF and cognitive function in people with metabolic disorders, as the current research is inconclusive. However, healthcare professionals can use the review to understand the potential beneficial effects of IF on cognition and metabolic health in humans.
Abstract
Background: The potential positive interaction between intermittent fasting (IF) and brain-derived neurotrophic factor (BDNF) on cognitive function has been widely discussed. This systematic review tried to assess the efficacy of interventions with different IF regimens on BDNF levels and their association with cognitive functions in humans. Interventions with different forms of IF such as caloric restriction (CR), alternate-day fasting (ADF), time-restricted eating (TRE), and the Ramadan model of intermittent fasting (RIF) were targeted. Methods: A systematic review was conducted for experimental and observational studies on healthy people and patients with diseases published in EMBASE, Scopus, PubMed, and Google Scholar databases from January 2000 to December 2023. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statements (PRISMA) for writing this review. Results: Sixteen research works conducted on healthy people and patients with metabolic disorders met the inclusion criteria for this systematic review. Five studies showed a significant increase in BDNF after the intervention, while five studies reported a significant decrease in BDNF levels, and the other six studies showed no significant changes in BDNF levels due to IF regimens. Moreover, five studies examined the RIF protocol, of which, three studies showed a significant reduction, while two showed a significant increase in BDNF levels, along with an improvement in cognitive function after RIF. Conclusions: The current findings suggest that IF has varying effects on BDNF levels and cognitive functions in healthy, overweight/obese individuals and patients with metabolic conditions. However, few human studies have shown that IF increases BDNF levels, with controversial results. In humans, IF has yet to be fully investigated in terms of its long-term effect on BDNF and cognitive functions. Large-scale, well-controlled studies with high-quality data are warranted to elucidate the impact of the IF regimens on BDNF levels and cognitive functions.
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Patients' and professionals' experiences and perspectives of obesity in health-care settings: a synthesis of current research.
Mold, F, Forbes, A
Health expectations : an international journal of public participation in health care and health policy. 2013;16(2):119-42
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Obesity is a complex condition, and likely to be the result of a range of biological, psychological, and social factors, making it one of the most difficult and challenging health problems to manage. Obesity is often stigmatised, with obese people being subject to discrimination that could affect their access to therapies or the success of such therapies. This review looked at current research examining the experiences of both obese people and health‐care professionals. The authors reviewed a total of 30 studies. From the studies that explored patient experiences and perspectives, four themes emerged: i) ambivalence of health professionals towards patients’ needs leading to a sense of personal ambivalence for obese individuals in accessing and using services; ii) experience of weight-based stigma leading to feelings of powerlessness and humiliation; iii) negative experiences with health-care professionals leading to a reluctance to access services and/or engage in positive health behaviours; and iv) experiences of stigmatisation leading to poorer psychological health and negative behaviours. The studies that explored health professionals’ experiences and perspectives found differences in how professionals view obese patients that included ambivalence, and negative attitudes and beliefs towards overweight people. One study found that overweight and obese women were less likely to undergo routine cancer screening procedures such as cervical screening and mammograms. The studies presented in this review show that obesity has a strong social effect, not only on how obese individuals view themselves, but also on how they access and interact with health‐care providers. This can impact negatively on psycho‐emotional functioning, on the uptake of health care and on the experience of care of obese people. Given the rising levels of obesity, further work is essential to improve the health‐care provision for this population.
Abstract
BACKGROUND Obesity-related stigma likely influences how obese people interact with health-care professionals and access health care. AIM: To undertake a synthesis of studies examining the views and experiences of both obese people in relation to their health-care provision and health-care professionals in providing care to obese patients. SEARCH STRATEGY A systematic search of key electronic databases relating to professional or patient experiences of, or perspectives on, obesity was performed in 2008 and updated in 2010. Reference lists of article bibliographies were searched, along with hand searches of relevant journals. INCLUSION CRITERIA Studies were screened against explicit inclusion criteria and published between 1990 and 2010. Findings were examined and organized thematically. DATA EXTRACTION Data were extracted focusing on obesity, stigma and access to health-care services. All included studies were subject to critical appraisal to assess the quality of the research. FINDINGS Thirty studies were identified. All the studies reported obesity impacting on health-care interactions. Key themes identified were experiences of stigma and feelings of powerlessness, treatment avoidance, psycho-emotional functioning, professional attitudes, confidence and training, variations in health contact time and finally, differences in treatment options and preventative measures. CONCLUSION Obesity is a stigmatized condition that impacts negatively on the relationship between patients and health-care providers. Given the increasing prevalence of obesity and the range of therapeutic options available, further work is necessary to understand how the presence of obesity affects health-care interactions and decision making.
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Do implementation intentions help to eat a healthy diet? A systematic review and meta-analysis of the empirical evidence.
Adriaanse, MA, Vinkers, CD, De Ridder, DT, Hox, JJ, De Wit, JB
Appetite. 2011;56(1):183-93
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Eating a healthy diet reduces the likelihood of becoming overweight or chronically ill. Many people are aware of the health benefits of eating a healthy diet, and are hence motivated to eat healthily. This study is a review and meta-analysis with the aim to evaluate the effectiveness of setting implementation intentions (the where, when and how planning in goal setting) in promoting healthy eating behaviour. Results indicate that implementation intentions can be effective in increasing healthy eating behaviours with 12 studies showing an overall medium size effect on increasing fruit and vegetable consumption. Authors conclude that implementation intentions to promote healthy eating have more promising effects that those aiming to diminish unhealthy eating patterns.
Abstract
OBJECTIVE This systematic review and meta-analysis examined whether implementation intentions are an effective tool to help people put their intentions to eat a healthy diet into practice. Additionally, it was investigated whether the quality of the outcome measures and the quality of the control conditions that are used in these studies influence implementation intentions' effectiveness. METHODS Twenty three empirical studies investigating the effect of implementation intentions on eating behavior were included. In assessing the empirical evidence, a distinction was made between studies that aim to increase healthy eating (i.e., eating more fruits) and studies that aim to diminish unhealthy eating (i.e., eating fewer unhealthy snacks). RESULTS Implementation intentions are an effective tool for promoting the inclusion of healthy food items in one's diet (Cohen's d=.51), but results for diminishing unhealthy eating patterns are less strong (Cohen's d=.29). For studies aiming to increase healthy eating, it was found that higher quality outcome measures and lower quality control conditions tended to yield stronger effects. CONCLUSION Implementation intentions are somewhat more effective in promoting healthy eating than in diminishing unhealthy eating, although for some studies promoting healthy eating effect sizes may have been inflated due to less than optimal control conditions.