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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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Modulating the Gut Microbiome in Multiple Sclerosis Management: A Systematic Review of Current Interventions.
Tsogka, A, Kitsos, DK, Stavrogianni, K, Giannopapas, V, Chasiotis, A, Christouli, N, Tsivgoulis, G, Tzartos, JS, Giannopoulos, S
Journal of clinical medicine. 2023;12(24)
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Multiple sclerosis (MS) is an autoimmune disease caused by the altered immune system mistakenly attacking the central nervous system. While genetics play a leading causative role in the manifestation of this disease, other contributing environmental factors can also exist, such as a disruption in the intestinal microbial composition. Previous research has shown that the bidirectional communication between the brain's and gut's health, also known as the gut-brain axis, may contribute to the prognosis of MS. Modulating gut microbial composition can be a therapeutic strategy in MS patients to manage symptoms and prevent disease progression. This systematic review assessed different protocols for modulating gut microbial composition, including dietary modifications, probiotic use, intermittent fasting, and faecal microbial transplantation. The review included thirteen studies that compared the effects of the above gut microbial modulation intervention protocols in MS patients with healthy participants. While different dietary modification strategies improved MS symptoms, probiotic supplementations and intermittent fasting reduced inflammation, and faecal microbial transplantation showed promising positive effects in a few reports. Due to the methodological limitations of the included studies, further robust studies are required to evaluate the beneficial effects of gut microbial modulation strategies in reducing the symptoms of MS patients. However, healthcare professionals can use the results of this study to understand the benefits of gut microbial modulation in MS patients.
Abstract
This review attempted to explore all recent clinical studies that have investigated the clinical and autoimmune impact of gut microbiota interventions in multiple sclerosis (MS), including dietary protocols, probiotics, fecal microbiota transplantation (FMT), and intermittent fasting (IF). Methods: Thirteen studies were held between 2011 and 2023 this demonstrated interventions in gut microbiome among patients with MS and their impact the clinical parameters of the disease. These included specialized dietary interventions, the supply of probiotic mixtures, FMT, and IF. Results: Dietary interventions positively affected various aspects of MS, including relapse rates, EDSS disability scores, MS-related fatigue, and metabolic features. Probiotic mixtures showed promising results on MS-related fatigue, EDSS parameters, inflammation; meanwhile, FMT-though a limited number of studies was included-indicated some clinical improvement in similar variables. IF showed reductions in EDSS scores and significant improvement in patients' emotional statuses. Conclusions: In dietary protocols, clinical MS parameters, including relapse rate, EDSS, MFIS, FSS, and MSQoL54 scales, were significantly improved through the application of a specific diet each time. Probiotic nutritional mixtures promote a shift in inflammation towards an anti-inflammatory cytokine profile in patients with MS. The administration of such mixtures affected disability, mood levels, and quality of life among patients with MS. FMT protocols possibly demonstrate a therapeutic effect in some case reports. IF protocols were found to ameliorate EDSS and FAMS scores. All interventional means of gut microbiome modulation provided significant conclusions on several clinical aspects of MS and highlight the complexity in the relationship between MS and the gut microbiome.
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The effects of time-restricted eating on sleep, cognitive decline, and Alzheimer's disease.
Ezzati, A, Pak, VM
Experimental gerontology. 2023;171:112033
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The ageing population is expected to double, with one in four people being over 65 years in Western countries by 2050. As a consequence, the presentation of age-related disorders like Alzheimer's disease (AD) and mild cognitive impairment (MCI) is likely to increase. MCI, a pre-stage of dementia, is considered reversible. However, there are no known cures for AD so far. Hence interventions such as lifestyle modifications that can delay the onset and progression of the disease are of great interest. Previous research demonstrated that calorie restriction (CR) and time-restricted eating (TRE) have beneficial effects on brain function. The authors of this article sought to summarize the current evidence of such eating patterns, as well as their underlying mechanisms and potential benefits concerning MCI and AD. The review also looked at sleep - as sleep disturbances are a risk factor and are associated with both conditions - and the effects of sleep on cognitive decline and neuroinflammatory markers. TRE presents itself as a promising intervention as it can restore the integrity of the blood-brain barrier and support healthy brain function whilst reducing oxidative stress and inflammation. Furthermore, it can be leveraged for weight and glucose management. Preliminary results also indicate a positive impact on sleep, with adequate sleep benefiting cognitive health. As this is a relatively new field, there is still much more to be understood about the underlying mechanisms, with the optimal time window for fasting needing to be determined. The authors advocate for more research on how TRE and sleep relates to neurodegenerative disease.
Expert Review
Conflicts of interest:
None
Take Home Message:
- To highlight the potential benefits of time-restricted eating (TRE) as a potential preventative approach to delay the onset and progression of neurodegenerative disease such as AD
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
- The authors highlight Alzheimer's disease (AD) is the most prevalent neurodegenerative disease affecting over 50 million aging people worldwide. While no cure is known for AD, this review proposes lifestyle interventions such as time-restricted eating (TRE) as a potential approach to delay the onset and progression of a neurodegenerative disease and could hint at autophagic mechanisms
- TRE involves strategically limiting the eating window to 8- to 12-h with fasting—drinking only water and calorie-free coffee/tea—for 12 to 16 h within a 24-h cycle.
Objectives
- To investigate the effects of TRE on sleep and cognitive decline in healthy individuals
Results
- Nine RCTs with varied length between one and sixteen weeks were examined
- A 5-week randomised controlled trial (RCT) showed no significant change in sleep quality between early TRE (fasting between 6 a.m.–3 p.m.), mid-day TRE (11 a.m.–8 p. m.) and control (ad lib intake) in 82 healthy subjects without obesity but the sleep quality improvement was greater in early TRE group (PSQI:Δ=−1.08±1.78vs.Δ=−0.22±2.19andΔ=−0.36±1.73, respectively).
- Sleep quality using the myCircadianClock app reported significant improvement in sleep quality (23 %) following a 12-week single arm intervention of 10-h TRE.
- Following a 16-week TRE intervention sleep duration was reported to be improved from a subjective score of 6 at base line to 8 after 36 weeks in eight overweight and obese subjects; however, the study used a subjective self-assessment survey for measuring sleep duration.
- The Pittsburgh Sleep Quality Index (PSQI) was carried out to assess sleep quality and disturbances in six trials but no trial reported significant improvement in sleep quality using the PSQI survey with TRE
Conclusion
- Authors highlight TRE as promising for its potential to reduce the markers of aging and neurodegenerative disease.
Clinical practice applications:
- To inform practitioners of the potential benefits of TRE that involves limiting the eating window to 8- to 12-h with fasting—drinking only water and calorie-free coffee/tea—for 12 to 16 h within a 24-h cycle.
- TRE may improve regulation of circadian rhythm and autophagy through aligning food intake with circadian rhythm, which coordinates metabolism and physiological functions including glucose, insulin sensitivity, lipid levels, energy expenditure, inflammation, sleep and cognitive function.
- TRE activates a metabolic switch which occurs 12–36 h after fasting is initiated and free fatty acids are released into the blood.
- TRE improved sleep quality and sleep duration, where a longer fasting period in TRE approach (≥12 h fasting) was associated with significantly higher sleep duration.
Considerations for future research:
- The potential benefits of TRE in neurodegenerative diseases such as AD should be further investigated clinically.
- The optimal time to initiate fasting needs to be identified in future trials.
- The potential benefits of TRE in neurodegenerative diseases such as AD in the context of sleep should be further investigated.
Abstract
According to the United Nations, by 2050, one in six individuals will be over age 65 globally, and one in four people would be aged 65 and older in western countries. The unprecedented growth of the aging population is associated with increased age-related disorders like Alzheimer's disease (AD) and Mild cognitive impairment (MCI). To date, no cure is known for AD, thus lifestyle interventions including calorie restriction (CR) and time-restricted eating (TRE) are proposed as potential approach to delay the onset and progression of the disease. Sleep disturbances are common in people with MCI and AD. Moreover, accumulating data indicates that pro-inflammatory cytokines including tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8 and IL-10 increase in individuals with AD and MCI versus healthy subjects. Thus, the purpose of the present review is to describe the potential effects of TRE on sleep, cognition decline, and neuroinflammatory markers in humans. Preliminary evidence suggests that TRE may produce neuroprotective effects on cognition and reduce neuroinflammatory markers related to AD in humans. To date, no studies investigated the effects of TRE on sleep disturbances and patients with AD. Thereby, the impact of TRE on cognition in individuals with cognitive decline and AD needs to be investigated further in randomized controlled trials (RCTs).
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The effects of time-restricted eating and weight loss on bone metabolism and health: a 6-month randomized controlled trial.
Papageorgiou, M, Biver, E, Mareschal, J, Phillips, NE, Hemmer, A, Biolley, E, Schwab, N, Manoogian, ENC, Gonzalez Rodriguez, E, Aeberli, D, et al
Obesity (Silver Spring, Md.). 2023;31 Suppl 1:85-95
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Intermittent fasting (IF) involves an alternation of abstinence and consumption of food and caloric beverages over a cycle of hours to days. Time-restricted feeding (in animals) or eating (TRE in humans) is a form of IF that entails restricting eating within a window of 4 to 12 hours per 24-hour cycle and prolonging the time spent in the fasted state to realign eating-fasting patterns with circadian rhythms. The aim of this study was to explore the impact of a 6-month randomised controlled trial of TRE versus standard dietary advice (SDA, active control arm) on bone metabolism and health in a population with at least one component of the metabolic syndrome. This study is a secondary analysis of an open-label 6-month randomised controlled trial in which participants who ate within a time interval > 14 hours per 24-hour cycle (n=54) were randomised to TRE or SDA (active control) with a 1:1 allocation ratio. A total of 42 participants (76% women) with available bone turnover markers and/or bone mass measurements were included in this study. Results show that there weren’t any detrimental effects on bone health outcomes i.e. bone metabolism or bone loss after 6 months of TRE. Additionally, weight loss following a period of TRE might be associated with small bone-sparing effects compared with SDA. Authors conclude that future studies of longer duration (>6 months) assessing multiple bone phenotypes are required in order to confirm the study’s findings and explore the effects of various TRE regimens particularly among individuals at risk for bone fragility such as postmenopausal women and the elderly.
Abstract
OBJECTIVE This study explored the impact of time-restricted eating (TRE) versus standard dietary advice (SDA) on bone health. METHODS Adults with ≥1 component of metabolic syndrome were randomized to TRE (ad libitum eating within 12 hours) or SDA (food pyramid brochure). Bone turnover markers and bone mineral content/density by dual energy x-ray absorptiometry were assessed at baseline and 6-month follow-up. Statistical analyses were performed in the total population and by weight loss response. RESULTS In the total population (n = 42, 76% women, median age 47 years [IQR: 31-52]), there were no between-group differences (TRE vs. SDA) in any bone parameter. Among weight loss responders (≥0.6 kg weight loss), the bone resorption marker β-carboxyterminal telopeptide of type I collagen tended to decrease after TRE but increase after SDA (between-group differences p = 0.041), whereas changes in the bone formation marker procollagen type I N-propeptide did not differ between groups. Total body bone mineral content decreased after SDA (p = 0.028) but remained unchanged after TRE (p = 0.31) in weight loss responders (between-group differences p = 0.028). Among nonresponders (<0.6 kg weight loss), there were no between-group differences in bone outcomes. CONCLUSIONS TRE had no detrimental impact on bone health, whereas, when weight loss occurred, it was associated with some bone-sparing effects compared with SDA.
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Alternate-Day Fasting Combined with Exercise: Effect on Sleep in Adults with Obesity and NAFLD.
Ezpeleta, M, Gabel, K, Cienfuegos, S, Kalam, F, Lin, S, Pavlou, V, Varady, KA
Nutrients. 2023;15(6)
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Non-alcoholic fatty liver disease (NAFLD) is defined as the presence of 5% or more fat in the liver, confirmed by hepatic imaging or biopsy. Poor sleep may adversely affect insulin sensitivity and inflammatory status, thereby contributing to the development and progression of NAFLD. The aim of this study was to investigate how intermittent fasting combined with exercise impacts body weight and sleep measures in adults with NAFLD. This study was a secondary analysis of a 3-month randomised, controlled, parallel-arm study. Participants were randomized to 1 of 4 intervention groups: alternate-day fasting (ADF) plus exercise, ADF alone, exercise alone, or a no-intervention control group. Results showed that intermittent fasting combined with exercise produced significant reductions in body weight and intrahepatic triglyceride content but no changes in sleep quality, duration, insomnia severity, or risk of obstructive sleep apnoea. Authors conclude that the weight loss induced by ADF combined with exercise does not improve sleep quality, duration, insomnia severity or risk of obstructive sleep apnea in individuals with obesity and NAFLD.
Abstract
Objective: This study investigated how alternate-day fasting (ADF) combined with aerobic exercise impacts body weight and sleep in adults with non-alcoholic fatty liver disease (NAFLD). Methods: Adults with obesity and NAFLD (n = 80) were randomized into one of four groups for 3 months: combination of ADF (600 kcal "fast day," alternated with an ad libitum intake "feast day") and moderate-intensity aerobic exercise (five sessions per week, 60 min/session); ADF alone; exercise alone; or a no-intervention control group. Results: By month 3, body weight and intrahepatic triglyceride content decreased (p < 0.001, group × time interaction) in the combination group versus the exercise group and control group, but not versus the ADF group. Sleep quality, measured by the Pittsburgh Sleep Quality Inventory (PSQI), did not change in the combination group (baseline: 6.0 ± 0.7; month 3: 5.6 ± 0.7), ADF group (baseline: 8.9 ± 1.0; month 3: 7.5 ± 0.8), or exercise group (baseline: 6.4 ± 0.6; month 3: 6.7 ± 0.6), versus controls (baseline: 5.5 ± 0.7; month 3: 4.6 ± 0.5). Wake time, bedtime, sleep duration, and insomnia severity did not change (no group x time interaction) over the course of the study in any group. Risk for obstructive sleep apnea was present in 30% of combination subjects, 75% of ADF subjects, 40% of exercise subjects, and 75% of controls, and did not change in the intervention groups, versus controls, by month 3. No associations were observed between changes in body weight, intrahepatic triglyceride content, and any sleep outcome. Conclusions: The weight loss induced by ADF combined with exercise does not improve sleep quality, duration, insomnia severity, or risk of obstructive sleep apnea in individuals with NAFLD.
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Hypnotherapy, Intermittent Fasting, and Exercise Group Programs in Atopic Dermatitis: A Randomized Controlled Explorative Clinical Trial During the COVID-19 Pandemic.
Rotter, G, Teut, M, Schleicher, R, Dell'Oro, M, Ortiz, M, Binting, S, Tissen-Diabaté, T, Roll, S, Michalsen, A, Staab, D, et al
Journal of integrative and complementary medicine. 2023;29(2):99-110
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Relaxation techniques, diet, and exercise can diminish atopic dermatitis (AD) symptoms. Patients with AD worry about the side-effects of the medical treatment for AD thus the majority try to engage in potentially healthy lifestyle behaviours. The aim of this study was to exploratively investigate the effectiveness of hypnotherapy, fasting with diet adjustments, and exercise in adult AD patients This study is a four-armed, randomised controlled, single-centre, open explorative clinical trial. Patients were randomly assigned to one of the four groups: i) hypnotherapy group program (HTP), ii) intermittent fasting with diet adjustment group program (IFDP), iii) an exercise group program or the control group. The study was strongly impacted by confinements and research restrictions due to the coronavirus 2019 pandemic. However, results showed potential beneficial changes to baseline in perceived itching intensity, disease severity, and disease-specific quality of life for HTP and IFDP. Authors conclude that further high-quality clinical trials should be performed investigating the effectiveness and safety of hypnotherapy, fasting with diet adjustments, as well as exercise.
Abstract
Background: Patients with atopic dermatitis (AD) frequently use healthy lifestyle behaviors, although their benefits are unclear. This study's aim was to investigate the effectiveness of hypnotherapy, fasting with diet adjustments, and exercise in AD patients. Methods: In a four-armed randomized controlled monocenter open explorative clinical trial, adult patients with mild-to-moderate severe AD underwent, over 16 weeks, a five-session hypnotherapy group program (HTP), a five-session intermittent fasting with diet adjustment group program (IFDP), a five-session exercise group program (EP), or no study intervention (control) as add-on to topical corticosteroid use if required. Endpoints included subjectively perceived itching on a visual analogue scale (VAS, 0-100 mm); disease severity by SCORing Atopic Dermatitis (SCORAD); and adverse events (AEs). Endpoints were analyzed descriptively in the Full Analysis Set (FAS). Due to the coronavirus disease 2019 (COVID-19) pandemic, relevant changes to the study protocol included online in addition to "in-presence" group interventions, closing the study arm EP and premature trial termination before randomization of 120 intended patients. Results: During the COVID-19 pandemic, study recruitment was poor. The FAS included 20 patients (17 female) with 35.0 ± 12.1 (mean ± standard deviation [SD]) years of age. At baseline, mean ± SD for HTP (n = 6), IFDP (n = 4), EP (n = 1), and control (n = 9) were VAS itching 63.2 ± 18.0, 65.0 ± 13.9, 43.0 mm, 62.1 ± 17.3; SCORAD 43.0 ± 13.6, 47.0 ± 21.0, 60.3, 39.1 ± 15.6. After 16 weeks, endpoints were VAS itching 26.0 ± 16.4, 31.7 ± 9.9, 23.0 mm, 39.3 ± 27.0; SCORAD 24.1 ± 12.2, 29.1 ± 19.1, 49.1, 25.5 ± 14.4. No serious AEs related to the interventions were observed. Conclusion: Despite very small groups, study results indicated potential beneficial changes to baseline in perceived itching intensity, disease severity, and disease-specific quality of life for HTP and IFDP. Therefore, further clinical trials should be performed investigating the effectiveness and safety of all interventions. Clinical Trial Registration: January 31, 2020 German Clinical Trials Register (DRKS): DRKS00020557, Universal Trial Number (UTN): U1111-1247-1512.
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Macronutrient composition and its effect on body composition changes during weight loss therapy in patients with non-alcoholic fatty liver disease: Secondary analysis of a randomized controlled trial.
Lindqvist, C, Holmer, M, Hagström, H, Petersson, S, Tillander, V, Brismar, TB, Stål, P
Nutrition (Burbank, Los Angeles County, Calif.). 2023;110:111982
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Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and it is closely linked to overweight and obesity. Weight loss leads to an amelioration of NAFLD, which preferably should lead to loss of fat mass while maintaining lean body mass. The aim of this study was to examine if different diet compositions during weight loss therapy were associated with different reductions in abdominal fat mass compared with standard weight loss advice given by a physician. This study was a secondary analysis of data collected in an open-label, randomised controlled trial. The trial examined the effect of two popular weight loss diets, calorie-restricted intermittent fasting (5:2) and a calorie-restricted low-carbohydrate high-fat (LCHF) diet, compared with standard of care (SOC) on reduction in liver fat in 74 persons with NAFLD. Results show that a dietitian-led nutrition counselling treatment with an LCHF or 5:2 diet reduced weight to a higher extent than physician-supported SOC during a 12-wk treatment. Improvements in most of the variables related to body composition parameters and metabolic function were found, independent of dietary composition. Furthermore, during weight loss, visceral fat was mobilized to a greater extent than subcutaneous fat. Authors conclude that further studies are needed with a focus on the effect of diet composition on body composition changes during weight loss.
Abstract
OBJECTIVES Dietary composition may affect body composition during weight loss therapy. We tested the hypothesis of whether dietary macronutrient composition influences the reduction of total abdominal adipose tissue, subcutaneous adipose tissue (SAT), or visceral adipose tissue (VAT) during weight loss. METHODS Dietary macronutrient composition and body composition were analyzed as a secondary outcome of a randomized controlled trial of 62 participants with non-alcoholic fatty liver disease. Patients were randomly assigned to a calorie-restricted intermittent fasting (5:2), calorie-restricted low-carbohydrate high-fat (LCHF), or healthy lifestyle advice (standard-of-care) diet in a 12-wk intervention phase. Dietary intake was assessed by self-reported 3-d food diaries and by characterization of total plasma fatty acid profile. Percentage of energy intake (E%) from different macronutrients was calculated. Body composition was assessed by magnetic resonance imaging and anthropometric measurements. RESULTS The macronutrient composition differed significantly between the 5:2 (fat 36 E% and carbohydrates 43 E%) and the LCHF (fat 69 E% and carbohydrates 9 E%) groups (P < 0.001). Weight loss was similar in the 5:2 and LCHF groups (-7.2 [SD = 3.4] kg versus 8.0 [SD = 4.8] kg; P = 0.44) and significantly larger than for standard of care (-2.5 kg [SD = 2.3]; P < 0.001). The volume of total abdominal fat, adjusted for height, decreased on average by 4.7% (standard of care), 14.3% (5:2), and 17.7% (LCHF), with no significant differences between the 5:2 and LHCF groups (P = 0.32). VAT and SAT, adjusted for height, decreased on average by 17.1% and 12.7% for 5:2, respectively, and by 21.2% and 17.9% for LCHF, with no significant group differences (VAT [P = 0.16] and SAT [P = 0.10]). VAT was mobilized to a greater extent than SAT in all diets. CONCLUSIONS The 5:2 and LCHF diets had similar effects on changes in intraabdominal fat mass and anthropometrics during weight loss. This might indicate that overall weight loss is more important than diet composition to achieve changes in total abdominal adipose tissue, VAT, or SAT. The results of the present study suggest that there is a need for further studies on the effect of diet composition on body composition changes during weight loss therapy.
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Effect of Intermittent Fasting on Reproductive Hormone Levels in Females and Males: A Review of Human Trials.
Cienfuegos, S, Corapi, S, Gabel, K, Ezpeleta, M, Kalam, F, Lin, S, Pavlou, V, Varady, KA
Nutrients. 2022;14(11)
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Intermittent fasting is a term for three different diet regimes. Alternate day fasting involves a feast day where individuals can eat what they want followed by a water only day. The 5:2 diet involves 5 feast days and 2 fast days per week. Time-restricted eating (TRE) involves a short eating window of a specific number of hours per day. Although these are all popular diet regimes for weight loss, animal studies have highlighted concerns with regards to reproductive health. This review paper aimed to summarise the human research on the effects of intermittent fasting on reproductive hormone levels in both men and women. It was found that overall, there were very few studies, however evidence was found on the effect of intermittent fasting on some of the sex hormones. For women, moving calorie intake to earlier in the day may be of benefit to oestrogen, sex hormone binding globulin, and androgen levels in those with polycystic ovary syndrome (PCOS). In addition, a fasting diet may be of benefit to androgen and SHBG levels in women with PCOS. However even though weight loss may be achieved with intermittent fasting, this is insufficient to improve the gonadotrophins. Intermittent fasting was found to be safe in women who were breastfeeding, with no significant change to milk production. In men, TRE was found to negatively affect testosterone levels, but had no effect on SHBG. The effect of intermittent fasting on sex hormones may involve changes in the gut microbiome and circadian rhythms as a direct result of intermittent fasting. It was concluded that the sex hormone levels of women with PCOS may benefit from intermittent fasting, however in men it may be detrimental to sex hormone production. This study could be used by healthcare professionals to understand that recommending an intermittent fasting diet may be of benefit to hormone levels and fertility in women with PCOS, however this may not be the case for men.
Abstract
Intermittent fasting is a popular diet for weight loss, but concerns have been raised regarding the effects of fasting on the reproductive health of women and men. Accordingly, we conducted this literature review to clarify the effects of fasting on reproductive hormone levels in humans. Our results suggest that intermittent fasting decreases androgen markers (i.e., testosterone and the free androgen index (FAI)) while increasing sex hormone-binding globulin (SHBG) levels in premenopausal females with obesity. This effect was more likely to occur when food consumption was confined to earlier in the day (eating all food before 4 pm). In contrast, fasting did not have any effect on estrogen, gonadotropins, or prolactin levels in women. As for men, intermittent fasting reduced testosterone levels in lean, physically active, young males, but it did not affect SHBG concentrations. Interestingly, muscle mass and muscular strength were not negatively affected by these reductions in testosterone. In interpreting these findings, it is important to note that very few studies have been conducted on this topic. Thus, it is difficult to draw solid conclusions at present. From the limited data presented here, it is possible that intermittent fasting may decrease androgen markers in both genders. If this is the case, these results would have varied health implications. On the one hand, fasting may prove to be a valuable tool for treating hyperandrogenism in females with polycystic ovarian syndrome (PCOS) by improving menstruation and fertility. On the other hand, fasting may be shown to decrease androgens among males, which could negatively affect metabolic health and libido. More research is warranted to confirm these preliminary findings.
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Effects of the 5:2 intermittent fasting diet on non-alcoholic fatty liver disease: A randomized controlled trial.
Kord Varkaneh, H, Salehi Sahlabadi, A, Găman, MA, Rajabnia, M, Sedanur Macit-Çelebi, M, Santos, HO, Hekmatdoost, A
Frontiers in nutrition. 2022;9:948655
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Non-alcoholic fatty liver disease (NAFLD) is associated with modifiable risk factors such as obesity, diabetes and metabolic syndrome. The 5:2 diet is an intermittent fasting regimen in which you fast for two days and eat liberally for five days per week. Time-restricted eating or intermittent fasting is a great way to limit energy intake and manage metabolic markers, making fasting diets like the 5:2 a viable option for the treatment of NAFLD. In this study, fifty patients with NAFLD were randomly assigned to either the intermittent fasting (5:2) or the control group. In the 5:2 group, the intervention resulted in a modest reduction in calorie intake. Participants on the 5:2 diet showed significant improvements in biomarkers of NAFLD, inflammatory markers, and body composition after 12 weeks of intervention. An evaluation of the effectiveness of a 5:2 diet on improving lipid profiles and diabetes requires further robust research. This study provides healthcare professionals insight into the benefits of implementing intermittent fasting as a cost-effective and safe therapeutic method.
Abstract
Background and aims: Dietary regimens are crucial in the management of non-alcoholic fatty liver disease (NAFLD). The effects of intermittent fasting (IF) have gained attention in this regard, but further research is warranted. Thus, we aimed to ascertain the overall effects of the 5:2 IF diet (5 days a week of normal food intake and 2 consecutive fasting days) in patients with NAFLD compared to a control group (usual diet). Methods and results: A 12-week randomized controlled trial was performed to evaluate the effects of the 5:2 IF diet on anthropometric indices, body composition, liver indices, serum lipids, glucose metabolism, and inflammatory markers in patients with NAFLD. The IF group (n = 21) decreased body weight (86.65 ± 12.57-82.94 ± 11.60 kg), body mass index (30.42 ± 2.27-29.13 ± 1.95 kg/m2), waist circumference (103.52 ± 6.42-100.52 ± 5.64 cm), fat mass (26.64 ± 5.43-23.85 ± 5.85 kg), fibrosis (6.97 ± 1.94-5.58 ± 1.07 kPa), steatosis scores/CAP (313.09 ± 25.45-289.95 ± 22.36 dB/m), alanine aminotransferase (41.42 ± 20.98-28.38 ± 15.21 U/L), aspartate aminotransferase (34.19 ± 10.88-25.95 ± 7.26 U/L), triglycerides (171.23 ± 39.88-128.04 ± 34.88 mg/dl), high-sensitivity C-reactive protein (2.95 ± 0.62 -2.40 ± 0.64 mg/L), and cytokeratin-18 (1.32 ± 0.06-1.19 ± 0.05 ng/ml) values compared to the baseline and the end of the control group (n = 23)-p ≤ 0.05 were considered as significant. However, the intervention did not change the levels of high-density lipoprotein cholesterol, total cholesterol, low-density lipoprotein cholesterol, fasting blood sugar, insulin, HOMA-IR, and total antioxidant capacity. Conclusion: Adhering to the 5:2 IF diet can reduce weight loss and related parameters (fat mass and anthropometric indicators of obesity), as well as hepatic steatosis, liver enzymes, triglycerides, and inflammatory biomarkers in patients with NAFLD.
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The Effects of Intermittent Fasting and Continuous Energy Restriction with Exercise on Cardiometabolic Biomarkers, Dietary Compliance, and Perceived Hunger and Mood: Secondary Outcomes of a Randomised, Controlled Trial.
Keenan, S, Cooke, MB, Chen, WS, Wu, S, Belski, R
Nutrients. 2022;14(15)
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Obesity plays an important role in the development of cardiometabolic diseases. Excess body weight contributes to insulin resistance, unfavourable patterns of blood lipids and systemic inflammation, which are significant risk factors for cardiovascular disease and type 2 diabetes. Lifestyle modifications that restrict energy intake are an effective approach to attaining weight loss and reducing fat mass; however, continuous energy restrictions (CER) often have poor compliance in the long run. Intermittent fasting (IF) approaches present a promising alternative to CER and may promote increased compliance. The favourable changes in cardiometabolic health attained by an energy-restricted diet can be further amplified when combined with exercise. This paper is a secondary analysis from a 12-week intervention investigating the effects of a twice-weekly fast (5:2 IF; IFT group) and CER (CERT group) in 34 young, overweight but metabolically healthy participants when combined with resistance training. The analysis focused on changes in cardiometabolic blood markers, ratings of hunger, mood, energy and compliance as well as the participant's intention to continue with their prescribed diets post-intervention. Both dietary patterns improved blood lipids, namely reductions in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol over 12 weeks. Reductions in TC and LDL-C were more pronounced in the IFT group. No remarkable differences or changes in triglycerides, the inflammatory marker C-reactive Protein or markers of insulin resistance were seen in either group. Both groups reported high levels of dietary compliance and low levels of hunger, suggesting that both diets are well adhered to in the short to medium term. Some gender-specific differences were seen, but the author was unable to make conclusions due to the small study size. The analysis demonstrated that IF and CER, combined with resistance exercise, can improve some cardiometabolic risk biomarkers in overweight but metabolically healthy adults, independent of weight loss, with greater improvements with IF approaches.
Abstract
(1) Background: Excess weight in the form of adiposity plays a key role in the pathogenesis of cardiometabolic diseases. Lifestyle modifications that incorporate continuous energy restriction (CER) are effective at inducing weight loss and reductions in adiposity; however, prescribing daily CER results in poor long-term adherence. Over the past decade, intermittent fasting (IF) has emerged as a promising alternative to CER that may promote increased compliance and/or improvements in cardiometabolic health parameters independent of weight loss. (2) Methods: This paper presents a secondary analysis of data from a 12-week intervention investigating the effects of a twice-weekly fast (5:2 IF; IFT group) and CER (CERT group) when combined with resistance exercise in 34 healthy participants (17 males and 17 females, mean BMI: 27.0 kg/m2, mean age: 23.9 years). Specifically, changes in cardiometabolic blood markers and ratings of hunger, mood, energy and compliance within and between groups were analysed. Dietary prescriptions were hypoenergetic and matched for energy and protein intake. (3) Results: Both dietary groups experienced reductions in total cholesterol (TC; mean reduction, 7.8%; p < 0.001), low-density lipoprotein cholesterol (LDL-C; mean reduction, 11.1%; p < 0.001) and high-density lipoprotein cholesterol (mean reduction 2.6%, p = 0.049) over the 12 weeks. Reductions in TC and LDL-C were greater in the IFT group after adjustment for baseline levels and change in weight. No significant changes in markers of glucose regulation were observed. Both groups maintained high levels of dietary compliance (~80%) and reported low levels of hunger over the course of the intervention period. (4) Conclusions: Secondary data analysis revealed that when combined with resistance training, both dietary patterns improved blood lipids, with greater reductions observed in the IFT group. High levels of compliance and low reported levels of hunger throughout the intervention period suggest both diets are well tolerated in the short-to-medium term.