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Effects of Intermittent Energy Restriction Compared with Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers - A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults.
Schroor, MM, Joris, PJ, Plat, J, Mensink, RP
Advances in nutrition (Bethesda, Md.). 2024;15(1):100130
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Intermittent energy restriction (IER) diets, such as the 5:2 diet, time-restricted eating (TRE), and alternate-day fasting (ADF), are gaining popularity. According to previous research, IER protocols effectively manage obesity and may have many other health benefits, including improving metabolic health. This systematic review and meta-analysis of twenty-eight parallel-design randomised controlled trials looked at the benefits of IER protocols, such as ADF, TRE, and the 5:2 diet, and the effects of continuous energy restriction (CER) on anthropometric and cardiometabolic outcomes. The results of this systematic review and meta-analysis showed that both the IER and CER are equally beneficial. However, IER protocols showed greater but clinically insignificant improvements in fat-free mass and waist circumference in healthy adults. IER and CER protocols were not different in improving the lipid profile, glucose and insulin levels and blood pressure. Different IER diets showed different positive effects on metabolic parameters. Future robust studies are required to assess the effects of these energy-restriction diets on metabolic and anthropometric parameters because of the high variability in the included studies. However, healthcare professionals can use the results of this review to understand the potential clinical utility of various energy-restriction diets.
Abstract
The interest in intermittent energy restriction (IER) diets as a weight-loss approach is increasing. Different IER protocols exist, including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet. This meta-analysis compared the effects of these IER diets with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults. Twenty-eight trials were identified that studied TRE (k = 7), ADF (k = 10), or the 5:2 diet (k = 11) for 2-52 wk. Energy intakes between intervention groups within a study were comparable (17 trials), lower in IER (5 trials), or not reported (6 trials). Weighted mean differences (WMDs) were calculated using fixed- or random-effects models. Changes in body weight [WMD: -0.42 kg; 95% confidence interval (CI): -0.96 to 0.13; P = 0.132] and fat mass (FM) (WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362) were comparable when results of the 3 IER diets were combined and compared with those of CER. All IER diets combined reduced fat-free mass (WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044) and waist circumference (WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036) more than CER. Effects on body mass index [BMI (kg/m2)], glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), serum lipid and lipoprotein concentrations, and blood pressure did not differ. Further, TRE reduced body weight, FM, and fat-free mass more than CER, whereas ADF improved HOMA-IR more. BMI was reduced less in the 5:2 diet compared with CER. In conclusion, the 3 IER diets combined did not lead to superior improvements in anthropometrics and cardiometabolic risk markers compared with CER diets. Slightly greater reductions were, however, observed in fat-free mass and waist circumference. To what extent differences in energy intakes between groups within studies may have influenced these outcomes should be addressed in future studies.
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Mediterranean Diet and Physical Activity Nudges versus Usual Care in Women with Rheumatoid Arthritis: Results from the MADEIRA Randomized Controlled Trial.
Papandreou, P, Gioxari, A, Daskalou, E, Grammatikopoulou, MG, Skouroliakou, M, Bogdanos, DP
Nutrients. 2023;15(3)
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Rheumatoid arthritis (RA) is one of the most common autoimmune diseases. Various dietary patterns, including the Mediterranean diet (MD), and individual nutrients including certain types of fatty acids and vitamin D, have been investigated for their potential associations with the development and prognosis of RA. The aim of this study was to evaluate the effect of a personalized MD plan delivered through a clinical decisions support system (CDSS) platform versus usual care, in women with an RA diagnosis. This study is a single-blind (statistician), two-arm randomised controlled trial. Patients (n = 40 women with RA) were randomly allocated to the intervention or the control arm. Results show that a 12-week personalized MD plan, paired with physical activity (PA) promotion and delivered with the support of CDSS was successful in improving adherence to the MD, disease activity, PA levels, and a plethora of cardiometabolic outcomes among female patients with RA. Furthermore, disease activity was also associated with body mass index. The overall combined prevalence of overweight and obesity in the sample was high, namely 35% and 10%, respectively. Authors conclude that greater adherence to the MD was associated with an ameliorated dietary fat intake, body weight, body composition, and lower disease activity state. Thus, authors suggest that the adoption of the MD by patients with RA appears to be a feasible anti-inflammatory regime.
Abstract
In rheumatoid arthritis (RA), diet quality and nutritional status have been shown to impact the disease activity and adherence to the Mediterranean diet (MD) has been suggested as an anti-inflammatory regime to improve disease status and reduce cardiovascular risk. The Mediterranean DiEt In Rheumatoid Arthritis (MADEIRA) was a single-blind (statistician), two-arm randomized clinical trial, investigating the effects of a 12-week lifestyle intervention, including a personalized isocaloric MD plan with the promotion of physical activity (PA), supported through a clinical decision support systems (CDSS) platform, versus usual care in women with RA. Forty adult women with RA on remission were randomly allocated (1:1 ratio) to either the intervention or the control arm. The intervention group received personalized MD plans and lifestyle consultation on improving PA levels, whereas the controls were given generic dietary and PA advice, based on the National Dietary Guidelines. The primary outcome was that the difference in the MD adherence and secondary outcomes included change in disease activity (DAS28), anthropometric indices (BodPod), dietary intake, PA, vitamin D concentrations, and blood lipid profiles after 12 weeks from the initiation of the trial. At 3 months post-baseline, participants in the MD arm exhibited greater adherence to the MD compared with the controls (p < 0.001), lower DAS28 (p < 0.001), favorable improvements in dietary intake (p = 0.001), PA (p = 0.002), body weight and body composition (p < 0.001), blood glucose (p = 0.005), and serum 1,25(OH)2D concentrations (p < 0.001). The delivery of the MD and PA promotion through CDSS nudges in women with RA in an intensive manner improves the MD adherence and is associated with beneficial results regarding disease activity and cardiometabolic-related outcomes, compared with the usual care.
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Effects of oral nutrition supplements in persons with dementia: A systematic review.
Tangvik, RJ, Bruvik, FK, Drageset, J, Kyte, K, Hunskår, I
Geriatric nursing (New York, N.Y.). 2021;42(1):117-123
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Dementia is a chronic condition characterised as a decline in cognitive functioning that leads to dependence in the performance of daily activities, including nutritional sufficiency. As the dis-ease progresses, eating and drinking may become more difficult. The aim of this study was to investigate the effects of oral nutrition supplements (ONS) on nutritional intake and clinical outcomes in older persons with dementia. This study is a systemic review which included ten studies of which 9 where experimental studies (n=6 RCTs; n=3 non RCTs) based on patients with dementia who were undernourished. Results indicate that ONS improved daily intake of energy and protein, compliance was high, and more persons met the recommended nutrition intake. In fact, intervention with ONS improved nutritional status; however, no effects on cognitive or functional outcomes were reported. Authors conclude that there is the need for a more comprehensive intervention plan for people with cognitive impairments that addresses the individual nutritional challenges in order to systematically meet nutritional needs.
Abstract
OBJECTIVE Persons with dementia are at risk of malnutrition, evidenced by low dietary intake, which has consequences for nutritional status, activity of daily living and disease progression. The effects of oral nutrition supplements (ONS) on nutritional intake, nutritional status, and cognitive and physical outcomes in older persons with dementia were evaluated. METHODS PubMed, Medline, Embase, CINAHL and the Cochrane Central Register of Controlled Trials were searched in December 2017, and this was repeated in May 2019. The Preferred Reporting Items for Systematic Reviews and Analysis (PRISMA) checklist was used. Papers were considered if they presented experimental clinical trials using oral nutritional supplements to persons diagnosed with dementia, including Alzheimer's disease and mild cognitive impairment, and conducted in hospitals, nursing homes or homes. RESULTS We included ten articles reporting nine clinical trials. A total of 407 persons with dementia were included, of whom 228 used ONS for 7 to 180 days. Nutritional intake improved by 201 to 600 kcal/day. Energy intake from ordinary foods was not affected, thus ONS improved the persons daily intake of energy and protein. Body weight, muscle mass, and nutritional biomarkers in blood improved in the intervention groups compared with the control groups. No effects on cognition or physical outcomes were observed. CONCLUSION ONS increases the intake of energy and protein and improves nutritional status in persons with dementia; however, RCTs with longer intervention periods are needed to investigate the impact on cognitive and functional outcomes.
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Manipulation of Dietary Intake on Changes in Circulating Testosterone Concentrations.
Zamir, A, Ben-Zeev, T, Hoffman, JR
Nutrients. 2021;13(10)
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Androgens, like testosterone, are steroid hormones commonly associated with reproduction. However, they also govern metabolic functions, body composition and growth. Higher levels of circulating androgens enhance athletic performance by supporting metabolic activities such as protein production, regeneration and growth and by inhibiting breakdown processes. Manipulating testosterone to enhance athletic performance without the use of anabolic steroids hormones has been of much interest. As macro-and micronutrients can influence androgen hormones, this review examined whether specific energy and nutrient intake can ‘naturally’ manipulate testosterone levels. The authors describe the metabolic functions of testosterone before exploring the current evidence on selected plant extracts and nutrients and their impact on aromatase activity. Inhibiting aromatase can prevent androgens from being converted into oestrogen and thus may help to raise circulating androgens. Discussed are a range of plant-derived compounds, flavonoids, macronutrients and micronutrients (Vitamin D, Zinc and Magnesium) and their impact on testosterone levels. The authors conclude that the nutrients discussed have some supportive evidence, yet overall findings are inconclusive due to limited studies. Regarding macronutrients more research is available, and the evidence supports that low energy intake negatively impacts testosterone levels and performance. Whereby supplementation of vitamins crucial to testosterone production seems to provide value in cases of deficiency further research is required. This article yields an overview of plant compounds, macro-and micronutrients and their potential impact on circulating testosterone levels. While low energy intake and nutrient deficiencies appears to be unfavourable, the absence of clear evidence on other compounds would warrant further case-specific investigations.
Abstract
Elevations in the circulating concentration of androgens are thought to have a positive effect on the anabolic processes leading to improved athletic performance. Anabolic-androgenic steroids have often been used by competitive athletes to augment this effect. Although there has been concerted effort on examining how manipulating training variables (e.g., intensity and volume of training) can influence the androgen response to exercise, there has been much less effort directed at understanding how changes in both macronutrient and micronutrient intake can impact the androgen response. Thus, the focus of this review is to examine the effect that manipulating energy and nutrient intake has on circulating concentrations of testosterone and what the potential mechanism is governing these changes.
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Relationship between energy availability, energy conservation and cognitive restraint with performance measures in male endurance athletes.
Jurov, I, Keay, N, Hadžić, V, Spudić, D, Rauter, S
Journal of the International Society of Sports Nutrition. 2021;18(1):24
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Athletes who do endurance exercise sometimes experience low energy availability which can affect their performance. Low energy availability may lead to a syndrome called Relative energy deficiency in sports. This cross-sectional controlled study assessed the pre-race energy availability in twelve lean, healthy endurance athletes without pre-existing signs of relative energy deficiency. Results showed that two-thirds of the participants had low mean energy availability. Lower energy availability was associated with higher energy expenditure. Participants in the study deliberately restricted their energy intake to achieve an optimal body composition. This may have led to energy conservation in participants. However, the study failed to show any associations between energy conservation and energy availability. There is a need for more robust studies to determine the true cut-off value of energy availability in male endurance athletes. Healthcare professionals can use the results of this study to understand the need for eating behaviour screening to reduce disordered eating in endurance athletes and the clinical applicability of energy conservation assessment.
Abstract
BACKGROUND Low energy availability in male athletes has gained a lot of attention in recent years, but direct evidence of its effects on health and performance is lacking. The aim of this research was to objectively measure energy availability (EA) in healthy male endurance athletes without pre-existing relative energy deficiency signs during pre-race season. METHODS Twelve trained endurance athletes (performance level 3, 4, and 5) participated in the cross-sectional controlled laboratory study. Fat-free mass, exercise energy expenditure, and energy intake were measured to calculate EA. Resting energy expenditure was measured and estimated to assess energy conservation. Three specific performance tests were used to assess endurance, agility, and explosive strength performance. For psychological evaluation, the Three Factor Eating Questionnaire and a short Well-being questionnaire were completed. RESULTS Mean EA was 29.5 kcal/kg FFM/day. The majority (66.6%) had EA under the threshold for low EA in females. Critical cognitive restraint (≥13) was reported by 75% of participants. There were no differences in performance, blood values, or psychological evaluation when subjects were divided into two groups divided by EA = 30 kcal/kg FFM/day. Cognitive restraint was negatively associated with measured resting energy expenditure and energy conservation (r = -.578, p = .025 and r = -.549, p = .032, respectively). CONCLUSIONS The mean EA measured in this study supports the theory that the threshold for low EA in endurance male athletes might be under the threshold for females. In addition, we confirmed cognitive restraint could be useful for early detection of energy conservation. The high cognitive restraint as measured in our sample stressed the need of eating behavior screening in endurance athletes in order to reduce risk of any disordered eating patterns.
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Stratifying cellular metabolism during weight loss: an interplay of metabolism, metabolic flexibility and inflammation.
Tareen, SHK, Kutmon, M, de Kok, TM, Mariman, ECM, van Baak, MA, Evelo, CT, Adriaens, ME, Arts, ICW
Scientific reports. 2020;10(1):1651
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Obesity is a public health concern as it has been linked to cardiovascular diseases, type 2 diabetes and metabolic syndrome. The aim of this study was to identify and analyse expression profiles of individuals clustered by cellular metabolism centring on metabolic flexibility. This study clustered gene expression samples from a weight loss study (Yoyo study’ - Clinical Trial ID: NCT01559415) into two clusters, based on 291 genes associated with cellular metabolic fexibility. The study covers two diets: a low-calorie diet (LCD) and a very low-calorie diet (VLCD). All the participants of the study were Caucasian with a BMI between 28kg/m2 and 35 kg/m2, aged between 32 and 67 years old. Findings showed that the majority of the individuals had their metabolism associated genes downregulated after weight loss and weight maintenance, but also had an upregulation of immune system associated genes. Furthermore, individuals who had changed their metabolic profiles in response to caloric restriction had a significant retention of lost weight compared to individuals which had not changed their cluster membership. Authors conclude that their findings indicate possible cross-talk between cellular metabolism and inflammation.
Abstract
Obesity is a global epidemic, contributing significantly to chronic non-communicable diseases, such as type 2 diabetes mellitus, cardiovascular diseases and metabolic syndrome. Metabolic flexibility, the ability of organisms to switch between metabolic substrates, is found to be impaired in obesity, possibly contributing to the development of chronic illnesses. Several studies have shown the improvement of metabolic flexibility after weight loss. In this study, we have mapped the cellular metabolism of the adipose tissue from a weight loss study to stratify the cellular metabolic processes and metabolic flexibility during weight loss. We have found that for a majority of the individuals, cellular metabolism was downregulated during weight loss, with gene expression of all major cellular metabolic processes (such as glycolysis, fatty acid β-oxidation etc.) being lowered during weight loss and weight maintenance. Parallel to this, the gene expression of immune system related processes involving interferons and interleukins increased. Previously, studies have indicated both negative and positive effects of post-weight loss inflammation in the adipose tissue with regards to weight loss or obesity and its co-morbidities; however, mechanistic links need to be constructed in order to determine the effects further. Our study contributes towards this goal by mapping the changes in gene expression across the weight loss study and indicates possible cross-talk between cellular metabolism and inflammation.
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Time-restricted eating effects on performance, immune function, and body composition in elite cyclists: a randomized controlled trial.
Moro, T, Tinsley, G, Longo, G, Grigoletto, D, Bianco, A, Ferraris, C, Guglielmetti, M, Veneto, A, Tagliabue, A, Marcolin, G, et al
Journal of the International Society of Sports Nutrition. 2020;17(1):65
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Adequate nutrition is important for elite athletes, as nutrient availability influences energy expenditure, body composition, performance and exercise-induced immune responses. Time-restricted eating (TRE) is a form of intermittent fasting that has received much interest in recent years. Previous research of TRE suggested beneficial effects on performance in untrained individuals, by allowing weight loss whilst maintaining muscle functions. These qualities are of interest for endurance cyclists hence the authors of this study sought to investigate the impact of TRE in elite cyclists. Sixteen under-23 year old, elite cyclists were randomly assigned to eat within a TRE window of 8-hr or 15hr window during a 4-week, high-level endurance training phase. Both groups consumed their full estimated energy needs and markers such as fat and fat-free mass, VO2 max, basal metabolism, blood counts, anabolic hormones and inflammatory markers were measured. As a result, TRE produced weight loss, improved body composition and increased peak power output in relation to body weight without compromising aerobic performance. Furthermore, the TRE pattern proved helpful in mitigating some of the exercise-induced suppressions of the immune system. The authors concluded that TRE could be considered as part of a performance nutrition plan in endurance athletes. Particularly where there is a need to reduce body fat mass or for the management of training-induced depression of the immune system and associated respiratory infection susceptibility. This can be of clinical relevance in the support of endurance athletes.
Abstract
BACKGROUND Although there is substantial interest in intermittent fasting as a dietary approach in active individuals, information regarding its effects in elite endurance athletes is currently unavailable. The present parallel randomized trial investigated the effects of a particular intermittent fasting approach, called time-restricted eating (TRE), during 4 weeks of high-level endurance training. METHODS Sixteen elite under-23 cyclists were randomly assigned either to a TRE group or a control group (ND). The TRE group consumed 100% of its estimated daily energy needs in an 8-h time window (from 10:00 a.m. to 6:00 p.m.) whilst energy intake in the ND group was distributed in 3 meals consumed between 7:00 a.m. and 9:00 p.m. Fat and fat-free mass were estimated by bioelectrical impedance analysis and VO2max and basal metabolism by indirect gas analyzer. In addition, blood counts, anabolic hormones (i.e. free testosterone, IGF-1) and inflammatory markers (i.e. IL-6, TNF-α) were assessed. RESULTS TRE reduced body weight (- 2%; p = 0.04) and fat mass percentage (- 1.1%; p = 0.01) with no change in fat-free mass. Performance tests showed no significant differences between groups, however the peak power output/body weight ratio (PPO/BW) improved in TRE group due to weight loss (p = 0.02). Free testosterone and IGF-1 decreased significantly (p = 0.01 and p = 0.03 respectively) in TRE group. Leucocyte count decreased in ND group (p = 0.02) whilst the neutrophils-to-lymphocytes ratio (NLR) decreased significantly (p = 0.03) in TRE group. CONCLUSIONS Our results suggest that a TRE program with an 8-h feeding window elicits weight loss, improves body composition and increases PPO/BW in elite cyclists. TRE could also be beneficial for reducing inflammation and may have a protective effect on some components of the immune system. Overall, TRE could be considered as a component of a periodized nutrition plan in endurance athletes. TRIAL REGISTRATION This trial was retrospectively registered at clinicaltrials.gov as NCT04320784 on 25 March 2020.
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The Obemat2.0 Study: A Clinical Trial of a Motivational Intervention for Childhood Obesity Treatment.
Luque, V, Feliu, A, Escribano, J, Ferré, N, Flores, G, Monné, R, Gutiérrez-Marín, D, Guillen, N, Muñoz-Hernando, J, Zaragoza-Jordana, M, et al
Nutrients. 2019;11(2)
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Multicomponent interventions consisting of dietary modification, physical activity, behavioural therapy, and education have shown to improve body mass index, blood pressure, and lipids profile. The Obemat2.0 trail was designed and conducted to implement and to test the efficacy of a structured multicomponent motivational therapy to treat childhood obesity. The study is a randomised clustered clinical trial with a treatment on children with obesity lasting 12 months. The study had two arms: a control group and an intervention group. The recruitment started in June 2016 and the fieldwork is expected to end in June 2019. The study results will show whether a multicomponent program, including a bundle of motivational strategies conducted in primary centres by therapists with 12h of specific training could be more effective than usual care. Authors expect this clinical trial to open a window of opportunity to support professionals at the primary care level to treat childhood obesity.
Abstract
The primary aim of the Obemat2.0 trial was to evaluate the efficacy of a multicomponent motivational program for the treatment of childhood obesity, coordinated between primary care and hospital specialized services, compared to the usual intervention performed in primary care. This was a cluster randomized clinical trial conducted in Spain, with two intervention arms: motivational intervention group vs. usual care group (as control), including 167 participants in each. The motivational intervention consisted of motivational interviewing, educational materials, use of an eHealth physical activity monitor and three group-based sessions. The primary outcome was body mass index (BMI) z score increments before and after the 12 (+3) months of intervention. Secondary outcomes (pre-post intervention) were: adherence to treatment, waist circumference (cm), fat mass index (z score), fat free mass index (z score), total body water (kg), bone mineral density (z score), blood lipids profile, glucose metabolism, and psychosocial problems. Other assessments (pre and post-intervention) were: sociodemographic information, physical activity, sedentary activity, neuropsychological testing, perception of body image, quality of the diet, food frequency consumption and foods available at home. The results of this clinical trial could open a window of opportunity to support professionals at the primary care to treat childhood obesity. The clinicaltrials.gov identifier was NCT02889406.
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Prolonged Collagen Peptide Supplementation and Resistance Exercise Training Affects Body Composition in Recreationally Active Men.
Kirmse, M, Oertzen-Hagemann, V, de Marées, M, Bloch, W, Platen, P
Nutrients. 2019;11(5)
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Currently little is known concerning collagen protein supplementation combined with a prolonged resistance exercising training (RET) programme. The aim of this study was to determine the effects of long-term collagen peptide supplementation and RET on body composition, strength and muscle fibre cross-sectional surface area (fCSA) in 57 recreationally active men. In this double-blind, placebo-controlled study, participants were randomly allocated to receive either collagen peptides or placebo for 12 weeks. Both groups trained three times a week. Strength testing, bioimedance analysis and muscle biopsies were taken at baseline and post-intervention. Most notably the collagen group experienced a significant increase in fat-free mass while body fat mass remained unchanged, compared to the placebo group. Both groups showed significant increases in strength tests and the fCSA increased significantly without differences. Based on these results, the authors conclude collagen protein supplementation have positive impact on body composition however suggest further study include connective tissue in addition to muscle tissue to better understand the mechanisms underlying these changes.
Abstract
We aimed to determine the effects of long-term collagen peptide (CP) supplementation and resistance exercise training (RET) on body composition, strength, and muscle fiber cross-sectional area (fCSA) in recreationally active men. Fifty-seven young men were randomly and double-blinded divided into a group receiving either collagen peptides (COL, 15 g/day) or a placebo (PLA). Strength testing, bioimpedance analysis, and muscle biopsies were used prior to and after an RET intervention. Food record protocols were performed during the RET intervention. The groups trained three times a week for 12 weeks. Baseline parameters showed no differences between groups, and the external training load and dietary food intake were also similar. COL showed a significant increase in fat-free mass (FFM) compared with the placebo group (p < 0.05). Body fat mass (BFM) was unchanged in COL, whereas a significant increase in BFM was observed in PLA. Both groups showed significant increases in all strength tests, with a trend for a slightly more pronounced effect in COL. The fCSA of type II muscle fibers increased significantly in both groups without differences between the two groups. We firstly demonstrated improved body composition in healthy, recreationally active men subsequent to prolonged CP supplementation in combination with RET. As the observed increase in FFM was not reflected in differences in fCSA hypertrophy between groups, we assume enhanced passive connective tissue adaptations in COL due to CP intake.
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Acute Endothelial Benefits of Fat Restriction over Carbohydrate Restriction in Type 2 Diabetes Mellitus: Beyond Carbs and Fats.
Barbosa-Yañez, RL, Dambeck, U, Li, L, Machann, J, Kabisch, S, Pfeiffer, AFH
Nutrients. 2018;10(12)
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The control of type 2 diabetes mellitus has become a global challenge. Cardiovascular disease is a major cause of mortality in type 2 diabetes. The aim of the study is to examine and compare the effect of a hypocaloric very low carbohydrate diet versus hypocaloric low-fat diet on vascular function and visceral adipose tissue in type 2 diabetic patients. The study is a randomised parallel group intervention study with adult type 2 diabetes patients with an age range between 42 and 76 years. Results show that both dietary strategies effectively reduced body weight, total adipose tissue, visceral adipose tissue and lipid accumulation in the liver. However, participants following the low-fat diet experienced greater vascular function enhancements. Authors conclude that low-fat diet elicited advantageous effects on vascular function in patients with type 2 diabetes.
Abstract
BACKGROUND Cardiovascular diseases (CVD) are the major cause of mortality in type 2 diabetes patients (T2DM). The causes are embedded in a complex interplay between excess body fat, insulin resistance and serum lipid anomalies. Endothelial homeostasis is strongly affected by this pathogenic network. Even though metabolic changes and weight loss improve vascular endothelial function, the effect of different dietary approaches is still uncertain for type 2 diabetes patients. OBJECTIVE We aimed to compare the acute effects of a hypocaloric very low carbohydrate (VLC) diet versus a hypocaloric low fat (LF) diet on flow mediated dilation (FMD), intrahepatic lipid (IHL) accumulation and visceral adipose tissue as independent risk factors of CVD in T2DM patients. DESIGN 36 T2DM patients (age 63 ± 8 years, 60% females) were randomly assigned to the VLC diet (4⁻10% of total energy intake (E)) or to the LF diet (<30% E) for 3 weeks. Endothelial function was assessed by the flow mediated dilation (FMD) method. Adipose tissue depots and IHL were determined by magnetic resonance. RESULTS Both dietary strategies reduced body weight, body fat content and IHL. Unexpectedly, the LF group experienced significantly greater enhancement of FMD, compared to the VLC group. The FMD showed a positive correlation with protein intake and fat intake in the LF group, while it revealed a negative correlation with protein intake in the VLC diet group. CONCLUSIONS Reduction of total and hepatic adiposity was shown to be successful using either the VLC or LF hypocaloric diets, however, improvements in FMD may be related to the interplay of fat and protein intake.