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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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Reducing meat and/or dairy consumption in adults: a systematic review and meta-analysis of effects on protein intake, anthropometric values, and body composition.
Habumugisha, T, Engebretsen, IMS, Måren, IE, Kaiser, CWM, Dierkes, J
Nutrition reviews. 2024;82(3):277-301
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Reduced consumption of meat and dairy is being encouraged over climate change fears, and health implications. However, meat and dairy provide high quality protein and nutrients and concerns have grown over nutrient deficiencies in people on plant-based diets. This systematic review and meta-analysis of 19 randomised control trials (RCTs) aimed to determine the effect of a reduced meat/dairy diet in protein intake, and body shape and composition. The results showed that the RCTs included ran for a median duration of 12 weeks. Participants on a reduced meat/dairy diet had lower protein intakes, and reduced meat/dairy diet had no effect on body weight, body mass index, waist circumference, body fat, or muscle mass. It was concluded that a low meat/dairy diet decreases protein intake, however it does not affect body shape, or composition. It was also concluded that studies of longer duration are warranted to determine long-term effects. This study could be used by healthcare professionals to understand that reduced meat/dairy intake over a moderate period of time may have no effect on body shape or composition but will result in lower protein intakes.
Abstract
CONTEXT Consumers are increasingly encouraged to reduce meat and dairy consumption. However, few meta-analyses of randomized controlled trials (RCTs) on the effect of reducing meat and/or dairy on (absolute) protein intake, anthropometric values, and body composition are available. OBJECTIVE The aim of this systematic review and meta-analysis was to evaluate the effect of reducing meat and/or dairy consumption on (absolute) protein intake, anthropometric values, and body composition in adults aged ≥ 45 years. DATA SOURCES The MEDLINE, Cochrane CENTRAL, Embase, ClinicalTrials.gov, and International Clinical Trials Registry Platform databases were searched up to November 24, 2021. DATA EXTRACTION Randomized controlled trials reporting protein intake, anthropometric values, and body composition were included. DATA ANALYSIS Data were pooled using random-effects models and expressed as the mean difference (MD) with 95%CI. Heterogeneity was assessed and quantified using Cochran's Q and I2 statistics. In total, 19 RCTs with a median duration of 12 weeks (range, 4-24 weeks) and a total enrollment of 1475 participants were included. Participants who consumed meat- and/or dairy-reduced diets had a significantly lower protein intake than those who consumed control diets (9 RCTs; MD, -14 g/d; 95%CI, -20 to -8; I2 = 81%). Reducing meat and/or dairy consumption had no significant effect on body weight (14 RCTs; MD, -1.2 kg; 95%CI, -3 to 0.7; I2 = 12%), body mass index (13 RCTs; MD, -0.3 kg/m2; 95%CI, -1 to 0.4; I2 = 34%), waist circumference (9 RCTs; MD, -0.5 cm; 95%CI, -2.1 to 1.1; I2 = 26%), amount of body fat (8 RCTs; MD, -1.0 kg; 95%CI, -3.0 to 1.0; I2 = 48%), or lean body mass (9 RCTs; MD, -0.4 kg; 95%CI, -1.5 to 0.7; I2 = 0%). CONCLUSION Reduction of meat and/or dairy appears to reduce protein intake. There is no evidence of a significant impact on anthropometric values or body composition. More long-term intervention studies with defined amounts of meat and dairy are needed to investigate the long-term effects on nutrient intakes and health outcomes. SYSTEMATIC REVIEW REGISTRATION PROSPERO registration no. CRD42020207325.
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Exploring choices of early nutritional support for patients with sepsis based on changes in intestinal microecology.
Yang, XJ, Wang, XH, Yang, MY, Ren, HY, Chen, H, Zhang, XY, Liu, QF, Yang, G, Yang, Y, Yang, XJ
World journal of gastroenterology. 2023;29(13):2034-2049
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Sepsis is a condition brought about by infection and results in organ dysfunction and gut microbiota imbalance. Nutrition plays a large part in recovery from sepsis, however it is unclear as to the optimal diet for gut microbial balance in individuals with sepsis. This randomised control trial of 30 individuals with sepsis aimed to determine the optimal delivery of nutrition for gut microbial health either through a gastric tube (TEN), through the jugular vein (TPN), or a mixture of the two modes (SPN). The results showed differences in gut microbiota composition between the different modes of nutrition. Enterococcus increased in TEN, Campylobacter decreased in TPN, and Dialister decreased in SPN groups. Fermentation products produced by gut microbiota also changed depending on the mode of nutrition, with the TEN group showing improvements amongst the most fermentation products. Individuals in the TEN group also showed improved immune system function alongside those in the SPN group. It was concluded that based upon improvements to the immune system and gut microbiota, TEN is the most suitable mode for nutrition in individuals with sepsis. This study could be used by healthcare professionals to understand that nutrition methods for individuals with sepsis aren’t equally effective and recovery may be faster if individuals receive nutrition through a gastric tube.
Abstract
BACKGROUND Sepsis exacerbates intestinal microecological disorders leading to poor prognosis. Proper modalities of nutritional support can improve nutrition, immunity, and intestinal microecology. AIM: To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology. METHODS Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University, China, between 2019 and 2021 with indications for nutritional support, were randomly assigned to one of three different modalities of nutritional support for a total of 5 d: Total enteral nutrition (TEN group), total parenteral nutrition (TPN group), and supplemental parenteral nutrition (SPN group). Blood and stool specimens were collected before and after nutritional support, and changes in gut microbiota, short-chain fatty acids (SCFAs), and immune and nutritional indicators were detected and compared among the three groups. RESULTS In comparison with before nutritional support, the three groups after nutritional support presented: (1) Differences in the gut bacteria (Enterococcus increased in the TEN group, Campylobacter decreased in the TPN group, and Dialister decreased in the SPN group; all P < 0.05); (2) different trends in SCFAs (the TEN group showed improvement except for Caproic acid, the TPN group showed improvement only for acetic and propionic acid, and the SPN group showed a decreasing trend); (3) significant improvement of the nutritional and immunological indicators in the TEN and SPN groups, while only immunoglobulin G improved in the TPN group (all P < 0.05); and (4) a significant correlation was found between the gut bacteria, SCFAs, and nutritional and immunological indicators (all P < 0.05). CONCLUSION TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators, as well as changes in intestinal microecology.
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An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition: An Interim Subgroup Analysis of the PREDIMED-Plus Randomized Clinical Trial.
Konieczna, J, Ruiz-Canela, M, Galmes-Panades, AM, Abete, I, Babio, N, Fiol, M, Martín-Sánchez, V, Estruch, R, Vidal, J, Buil-Cosiales, P, et al
JAMA network open. 2023;6(10):e2337994
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The Mediterranean diet (MedDiet), which focuses on whole grains, lean meat, fruits, vegetables, and low amounts of minimally processed foods has been shown in previous research to improve body composition and decrease fat storage around the middle. This randomised control trial of 1556 older adults aimed to determine the effects of combining a 30% lower energy version of the MedDiet in combination with physical exercise on body composition. After 3 years, the results showed that compared to a normal MedDiet without exercise, the lower energy version in combination with exercise improved body composition by decreasing total fat, and the fat stored around the organs and increasing muscle mass. However, benefits were more pronounced after 1 year and decreased slightly at 3 years. It was concluded that a low energy MedDiet in combination with physical activity may be able to improve the body composition of overweight and older adults with obesity. This study could be used by healthcare professionals to recommend a low energy MedDiet to older adults to promote weight loss, whilst attenuating muscle loss associated with ageing.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The addition of exercise to an energy-reduced diet, which focuses on whole grains, healthy fats, lean protein, and fruits and vegetables can emphasise positive effects on body composition in older adults.
- However, there is a loss of lean mass associated with this type of diet (contrary to author conclusions) and measures should be taken to monitor and increase protein intake to prevent or limit this loss.
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:
Introduction
This study aimed to determine the long-term effects of an energy reduced MedDiet in combination with physical activity on body composition.
Methods
- This is a predetermined 3-year interim analysis of a 6-year single-blind, randomised control trial of 1556 individuals aged 55-75 who are overweight or obese with metabolic syndrome.
- 760 individuals on 30% energy reduced MedDiet with limited processed foods, plus 45 minutes walking 6 days per week and behavioural and motivational support. [Intervention group]
- 761 on standard MedDiet without physical activity. [Control]
Results
Within group comparisons showed that individuals in the intervention group lost (P value represents baseline vs year 3):
- Total fat mass percentage (1-year vs baseline, −1.14%; 95% CI, −1.32% to −0.96%; 3-year vs baseline, −0.52%; 95% CI, −0.71% to −0.33% P=<0.001)
- Absolute visceral fat (1-year vs baseline, −154 g; 95% CI, −191 to −116 g; 3-year vs baseline, −75.1 g, 95% CI, −115 to −35.3 g P=<0.001)
- Absolute total fat after 1 year (mean change at 1 year vs baseline, −1677 g; 95% CI, −1930 to −1424 g) but regained some at year 3 (mean change at 3 years vs baseline, −1018 g; 95% CI, −1280 to −756 g P=<0.001)
- Absolute lean mass (mean change at 1 year vs baseline −300 g; 95% CI, −439 to −162 g) with further losses at year 3 (−626 g; 95% CI, −770 to −483 g P=0.001).
Within group comparisons also showed significantly increased:
- Total lean mass percentage, which was greater at year 1 than year 3 (1-year vs baseline, 1.07%; 95%CI, 0.90%-1.25%; 3-year vs baseline, 0.47%; 95% CI, 0.29%-0.65% P=<0.001).
As a result of total fat loss and some lean mass in the intervention group, the lean:fat mass ratio improved and was unchanged in the control group (between group differences (P=<0.001).
Compared to women, men may find the MedDiet + exercise more beneficial as it was shown that body composition changes were slightly more pronounced in men.
Conclusion
An energy-reduced MedDiet plus exercise emphasised positive changes to body composition compared to standard MedDiet in older adults who are overweight or have obesity.
Clinical practice applications:
- The recommendation of a reduced energy MedDiet in combination with physical activity to older people who are overweight or obese may improve body composition.
- Although lean mass loss slowed between years 1 and 3, other practices should be employed to attenuate the loss of lean mass associated with an energy-reduced MedDiet and ageing.
Considerations for future research:
- The research has not yet concluded but when it does, it will address the incidence of cardiovascular disease along with body composition changes.
- It will also look at long-term effects of the diet to determine longevity.
- Future research could focus on how to limit lean mass loss through the possibility of changing the type of exercise that accompanies the MedDiet.
Abstract
IMPORTANCE Strategies targeting body composition may help prevent chronic diseases in persons with excess weight, but randomized clinical trials evaluating lifestyle interventions have rarely reported effects on directly quantified body composition. OBJECTIVE To evaluate the effects of a lifestyle weight-loss intervention on changes in overall and regional body composition. DESIGN, SETTING, AND PARTICIPANTS The ongoing Prevención con Dieta Mediterránea-Plus (PREDIMED-Plus) randomized clinical trial is designed to test the effect of the intervention on cardiovascular disease prevention after 8 years of follow-up. The trial is being conducted in 23 Spanish research centers and includes men and women (age 55-75 years) with body mass index between 27 and 40 and metabolic syndrome. The trial reported herein is an interim subgroup analysis of the intermediate outcome body composition after 3-year follow-up, and data analysis was conducted from February 1 to November 30, 2022. Of 6874 total PREDIMED-Plus participants, a subsample of 1521 individuals, coming from centers with access to a dual energy x-ray absorptiometry device, underwent body composition measurements at 3 time points. INTERVENTION Participants were randomly allocated to a multifactorial intervention based on an energy-reduced Mediterranean diet (MedDiet) and increased physical activity (PA) or to a control group based on usual care, with advice to follow an ad libitum MedDiet, but no physical activity promotion. MAIN OUTCOMES AND MEASURES The outcomes (continuous) were 3-year changes in total fat and lean mass (expressed as percentages of body mass) and visceral fat (in grams), tested using multivariable linear mixed-effects models. Clinical relevance of changes in body components (dichotomous) was assessed based on 5% or more improvements in baseline values, using logistic regression. Main analyses were performed in the evaluable population (completers only) and in sensitivity analyses, multiple imputation was performed to include data of participants lost to follow-up (intention-to-treat analyses). RESULTS A total of 1521 individuals were included (mean [SD] age, 65.3 [5.0] years; 52.1% men). In comparison with the control group (n=761), participants in the intervention arm (n=760) showed greater reductions in the percentage of total fat (between group differences after 1-year, -0.94% [95% CI, -1.19 to -0.69]; 3 years, -0.38% [95% CI, -0.64 to -0.12] and visceral fat storage after 1 year, -126 g [95% CI, -179 to -73.3 g]; 3 years, -70.4 g [95% CI, -126 to -15.2 g] and greater increases in the percentage of total lean mass at 1 year, 0.88% [95% CI, 0.63%-1.12%]; 3-years 0.34% [95% CI, 0.09%-0.60%]). The intervention group was more likely to show improvements of 5% or more in baseline body components (absolute risk reduction after 1 year, 13% for total fat mass, 11% for total lean mass, and 14% for visceral fat mass; after 3-years: 6% for total fat mass, 6% for total lean mass, and 8% for visceral fat mass). The number of participants needed to treat was between 12 and 17 to attain at least 1 individual with possibly clinically meaningful improvements in body composition. CONCLUSIONS AND RELEVANCE The findings of this trial suggest a weight-loss lifestyle intervention based on an energy-reduced MedDiet and physical activity significantly reduced total and visceral fat and attenuated age-related losses of lean mass in older adults with overweight or obesity and metabolic syndrome. Continued follow-up is warranted to confirm the long-term consequences of these changes on cardiovascular clinical end points. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN89898870.
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The Influence of Whey Protein on Muscle Strength, Glycemic Control and Functional Tasks in Older Adults with Type 2 Diabetes Mellitus in a Resistance Exercise Program: Randomized and Triple Blind Clinical Trial.
Soares, ALS, Machado-Lima, A, Brech, GC, Greve, JMD, Dos Santos, JR, Inojossa, TR, Rogero, MM, Salles, JEN, Santarem-Sobrinho, JM, Davis, CL, et al
International journal of environmental research and public health. 2023;20(10)
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Type 2 Diabetes Mellitus (T2DM) is a common metabolic disease and the prevalence of T2DM is increasing among older adults. Resistance training is known to be an effective therapeutic strategy as it can positively influence the mechanisms of T2DM pathophysiology. Previous research suggests that whey protein supplementation can positively influence the different mechanisms of T2DM pathophysiology and improve muscle mass and glycaemic control. This triple-blinded, randomised controlled parallel-arm trial included twenty-eight male older adults to assess the effect of whey protein supplementation combined with resistance training for twelve weeks on glycaemic control, functional tasks, muscle strength, and body composition. The control group was supplemented with maltodextrin. All participants followed resistance training and were given nutritional guidance. Twelve weeks of resistance training improved muscle strength significantly. However, 20g whey protein supplementation did not improve performance in functional tasks, glycaemic control, or body composition in the test group of older adults with T2DM. Whey protein supplementation showed no significant synergetic effects when combined with resistance training in the test group. Due to the heterogeneity of the present study, further robust studies are warranted to investigate the effects of whey protein supplementation and resistance training. However, healthcare professionals can use the results of this study to understand the effect of resistance training alone and the safety profile of whey protein supplementation in older adults with T2DM.
Abstract
OBJECTIVES To evaluate the effect of whey protein (WP) supplementation associated with resistance training (RT) on glycemic control, functional tasks, muscle strength, and body composition in older adults living with type 2 diabetes mellitus (T2DM). Secondly, to evaluate the safety of the protocol for renal function. METHODS The population comprised twenty-six older men living with T2DM (68.5 ± 11.5 years old). The participants were randomly assigned to the Protein Group (PG) and the Control Group (CG). The handgrip test and evolution of exercise loads, according to the Omni Resistance Exercise Scale, evaluated muscle strength. Functional tasks were assessed by force platform in three different protocols: Sit-to-Stand, Step/Quick Turn, and Step Up/Over. Body composition was evaluated by bioimpedance and glycemic control and renal function were assessed by biochemical analyses. Both groups performed RT for 12 weeks, twice a week, prioritizing large muscle groups. Protein supplementation was 20 g of whey protein isolate and the CG was supplemented with an isocaloric drink, containing 20 g of maltodextrin. RESULTS There was a significant difference in muscle strength, according to the evolution of the exercise loads, but it was not confirmed in the handgrip test. However, there was no significant difference between the groups, regarding performance in functional tasks, glycemic control, or body composition. Renal function showed no alteration. CONCLUSION The intake of 20 g of WP in older male adults living with T2DM did not increase the effect of RT on muscle strength, functional tasks, and glycemic control. The intervention was proven safe regarding renal function.
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Effectiveness of wearable activity trackers to increase physical activity and improve health: a systematic review of systematic reviews and meta-analyses.
Ferguson, T, Olds, T, Curtis, R, Blake, H, Crozier, AJ, Dankiw, K, Dumuid, D, Kasai, D, O'Connor, E, Virgara, R, et al
The Lancet. Digital health. 2022;4(8):e615-e626
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A sedentary or physically inactive lifestyle significantly contributes to non-communicable diseases such as coronary heart disease, type 2 diabetes and stroke. Wearable activity trackers are low-cost solutions that encourage users to engage in physical activity. This umbrella review of systematic reviews and meta-analyses investigated the benefits of wearable activity trackers in improving physical activity levels and their beneficial effects on physiological and psychosocial outcomes. This umbrella review included thirty-nine systematic reviews, of which twenty-five systematic reviews included meta-analyses of the benefits of wearable trackers on physical activity levels. Results of this umbrella review suggest that wearable trackers increased physical activity levels, especially daily steps count and energy expenditure. The physiological outcomes included improvements in BMI, blood pressure, cholesterol, glycosylated haemoglobin, waist circumference, and body weight. There was also a slight improvement in the quality of life of the participants who used wearable activity trackers. Further robust studies are required to evaluate the effects of wearable trackers on the psychosocial outcomes in people with mental illness. However, healthcare professionals can use the results of this study to understand the impact of wearable trackers on physiological and psychosocial effects in a non-clinical population.
Abstract
Wearable activity trackers offer an appealing, low-cost tool to address physical inactivity. This systematic review of systematic reviews and meta-analyses (umbrella review) aimed to examine the effectiveness of activity trackers for improving physical activity and related physiological and psychosocial outcomes in clinical and non-clinical populations. Seven databases (Embase, MEDLINE, Ovid Emcare, Scopus, SPORTDiscus, the Cochrane Library, and Web of Science) were searched from database inception to April 8, 2021. Systematic reviews of primary studies using activity trackers as interventions and reporting physical activity, physiological, or psychosocial outcomes were eligible for inclusion. In total, 39 systematic reviews and meta-analyses were identified, reporting results from 163 992 participants spanning all age groups, from both healthy and clinical populations. Taken together, the meta-analyses suggested activity trackers improved physical activity (standardised mean difference [SMD] 0·3-0·6), body composition (SMD 0·7-2·0), and fitness (SMD 0·3), equating to approximately 1800 extra steps per day, 40 min per day more walking, and reductions of approximately 1 kg in bodyweight. Effects for other physiological (blood pressure, cholesterol, and glycosylated haemoglobin) and psychosocial (quality of life and pain) outcomes were typically small and often non-significant. Activity trackers appear to be effective at increasing physical activity in a variety of age groups and clinical and non-clinical populations. The benefit is clinically important and is sustained over time. Based on the studies evaluated, there is sufficient evidence to recommend the use of activity trackers.
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Effect of a Personalized Diet to Reduce Postprandial Glycemic Response vs a Low-fat Diet on Weight Loss in Adults With Abnormal Glucose Metabolism and Obesity: A Randomized Clinical Trial.
Popp, CJ, Hu, L, Kharmats, AY, Curran, M, Berube, L, Wang, C, Pompeii, ML, Illiano, P, St-Jules, DE, Mottern, M, et al
JAMA network open. 2022;5(9):e2233760
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Postprandial glycaemic response (PPGR) to foods can be different from person to person. This could be the reason why people experience different weight loss outcomes with standardised diets such as a low glycaemic index diet, low-fat diet or a low carbohydrate diet. In this single-centre, population-based, randomised, blinded clinical trial, 204 participants with irregular glucose metabolism and obesity were randomised to consume either a low-fat or personalised diet for six months in combination with fourteen behavioural change counselling sessions. The participants in the personalised diet group received a colour-coded meal score to indicate their estimated PPGR for different foods. The results of this study showed no significant weight reduction in the personalised diet group compared to the low-fat diet. Further robust studies are required to develop appropriate precision nutrition interventions for weight loss and energy balance. However, healthcare professionals can use the results of this study to understand that both a low-fat diet and a personalised diet, coupled with behavioural counselling, may be effective in promoting weight loss in obese populations with irregular glucose metabolism.
Abstract
IMPORTANCE Interindividual variability in postprandial glycemic response (PPGR) to the same foods may explain why low glycemic index or load and low-carbohydrate diet interventions have mixed weight loss outcomes. A precision nutrition approach that estimates personalized PPGR to specific foods may be more efficacious for weight loss. OBJECTIVE To compare a standardized low-fat vs a personalized diet regarding percentage of weight loss in adults with abnormal glucose metabolism and obesity. DESIGN, SETTING, AND PARTICIPANTS The Personal Diet Study was a single-center, population-based, 6-month randomized clinical trial with measurements at baseline (0 months) and 3 and 6 months conducted from February 12, 2018, to October 28, 2021. A total of 269 adults aged 18 to 80 years with a body mass index (calculated as weight in kilograms divided by height in meters squared) ranging from 27 to 50 and a hemoglobin A1c level ranging from 5.7% to 8.0% were recruited. Individuals were excluded if receiving medications other than metformin or with evidence of kidney disease, assessed as an estimated glomerular filtration rate of less than 60 mL/min/1.73 m2 using the Chronic Kidney Disease Epidemiology Collaboration equation, to avoid recruiting patients with advanced type 2 diabetes. INTERVENTIONS Participants were randomized to either a low-fat diet (<25% of energy intake; standardized group) or a personalized diet that estimates PPGR to foods using a machine learning algorithm (personalized group). Participants in both groups received a total of 14 behavioral counseling sessions and self-monitored dietary intake. In addition, the participants in the personalized group received color-coded meal scores on estimated PPGR delivered via a mobile app. MAIN OUTCOMES AND MEASURES The primary outcome was the percentage of weight loss from baseline to 6 months. Secondary outcomes included changes in body composition (fat mass, fat-free mass, and percentage of body weight), resting energy expenditure, and adaptive thermogenesis. Data were collected at baseline and 3 and 6 months. Analysis was based on intention to treat using linear mixed modeling. RESULTS Of a total of 204 adults randomized, 199 (102 in the personalized group vs 97 in the standardized group) contributed data (mean [SD] age, 58 [11] years; 133 women [66.8%]; mean [SD] body mass index, 33.9 [4.8]). Weight change at 6 months was -4.31% (95% CI, -5.37% to -3.24%) for the standardized group and -3.26% (95% CI, -4.25% to -2.26%) for the personalized group, which was not significantly different (difference between groups, 1.05% [95% CI, -0.40% to 2.50%]; P = .16). There were no between-group differences in body composition and adaptive thermogenesis; however, the change in resting energy expenditure was significantly greater in the standardized group from 0 to 6 months (difference between groups, 92.3 [95% CI, 0.9-183.8] kcal/d; P = .05). CONCLUSIONS AND RELEVANCE A personalized diet targeting a reduction in PPGR did not result in greater weight loss compared with a low-fat diet at 6 months. Future studies should assess methods of increasing dietary self-monitoring adherence and intervention exposure. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03336411.
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Molecular Regulators of Muscle Mass and Mitochondrial Remodeling Are Not Influenced by Testosterone Administration in Young Women.
Horwath, O, Moberg, M, Hirschberg, AL, Ekblom, B, Apró, W
Frontiers in endocrinology. 2022;13:874748
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Testosterone is a sex hormone normally found in higher amounts in adult males than females. Testosterone plays a number of important roles, including influencing muscle size and strength. Treatment with testosterone has been shown to increase lean mass and muscle strength in women as well as men. However, female-only studies are limited, and the precise mechanisms underlying these changes are not well understood. This randomised control trial examined the effect of testosterone administration on regulators of muscle protein turnover and mitochondrial function in muscle samples collected from young women. 48 healthy, pre-menopausal women were assigned to receive either 10mg of transdermal testosterone gel per day, or a placebo, for 10 weeks. Muscle samples were collected via biopsy before and after the intervention. Testosterone administration did not appear to have a significant effect on androgen receptors, 5-alpha reductase, anabolic signalling, or mitochondrial remodelling in muscle tissue. The researchers concluded that improvements in muscle size and oxidative capacity following testosterone administration cannot be explained by changes in protein expression related to muscle protein turnover or mitochondrial remodelling. The authors went on to suggest that the small sample size in this study may have reduced the ability to detect small but biologically relevant changes in protein levels. Within the research, there is large variability among studies in terms of sex, age, route of administration and length of treatment, which makes putting these findings into context of the wider literature difficult.
Abstract
Testosterone (T) administration has previously been shown to improve muscle size and oxidative capacity. However, the molecular mechanisms underlying these adaptations in human skeletal muscle remain to be determined. Here, we examined the effect of moderate-dose T administration on molecular regulators of muscle protein turnover and mitochondrial remodeling in muscle samples collected from young women. Forty-eight healthy, physically active, young women (28 ± 4 years) were assigned in a random double-blind fashion to receive either T (10 mg/day) or placebo for 10-weeks. Muscle biopsies collected before and after the intervention period were divided into sub-cellular fractions and total protein levels of molecular regulators of muscle protein turnover and mitochondrial remodeling were analyzed using Western blotting. T administration had no effect on androgen receptor or 5α-reductase levels, nor on proteins involved in the mTORC1-signaling pathway (mTOR, S6K1, eEF2 and RPS6). Neither did it affect the abundance of proteins associated with proteasomal protein degradation (MAFbx, MuRF-1 and UBR5) and autophagy-lysosomal degradation (AMPK, ULK1 and p62). T administration also had no effect on proteins in the mitochondria enriched fraction regulating mitophagy (Beclin, BNIP3, LC3B-I, LC3B-II and LC3B-II/I ratio) and morphology (Mitofilin), and it did not alter the expression of mitochondrial fission- (FIS1 and DRP1) or fusion factors (OPA1 and MFN2). In summary, these data indicate that improvements in muscle size and oxidative capacity in young women in response to moderate-dose T administration cannot be explained by alterations in total expression of molecular factors known to regulate muscle protein turnover or mitochondrial remodeling.
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Yogurt, cultured fermented milk, and health: a systematic review.
Savaiano, DA, Hutkins, RW
Nutrition reviews. 2021;79(5):599-614
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Many fermented foods are associated with health benefits, including fermented dairy products. Whereby diary itself is part of many nutritional guidelines, the guidances rarely distinguish between dairy and fermented dairy. This qualitative, systematic review sought to capture how consumption of fermented milk products influences health. The review included 108 studies, with over 70% reporting beneficial health outcomes. A small number of studies reported insignificant or neutral results and four unfavourable ones. The aspects of health that were considered included lactose digestion and tolerance, gut health and disease, diarrhoea and constipation, irritable bowel syndrome, cardiovascular health and disease, hypertension, blood lipids, cancer risk, colorectal/breast/prostate cancer, weight and body composition, diabetes risk and metabolic syndrome and bone health. The authors concluded that eating fermented dairy products aided lactose digestion and showed a consistent link with reduced risk of breast and colorectal cancer, type 2 diabetes, and improved weight maintenance, cardiovascular, bone, and gastrointestinal health. As dairy appears to increase the risk for prostate cancer, fermented dairy seems to be no different here to unfermented dairy at increasing the risk. Some potential mechanisms are proposed in the discussion section, how fermented dairy may elicit its health benefits. Given the predominant health benefits of fermented dairy, the authors encouraged to include fermented dairy into national nutrition guidelines and stress distinction between dairy and fermented dairy products. This review captures current evidence of the widespread health benefits of fermented dairy consumption worthwhile considering in clinical practice. In the absence of more clear findings in relation to prostate cancer and prevention, a cautious approach to dairy and fermented dairy consumption may be warranted.
Abstract
Consumption of yogurt and other fermented products is associated with improved health outcomes. Although dairy consumption is included in most dietary guidelines, there have been few specific recommendations for yogurt and cultured dairy products. A qualitative systematic review was conducted to determine the effect of consumption of fermented milk products on gastrointestinal and cardiovascular health, cancer risk, weight management, diabetes and metabolic health, and bone density using PRISMA guidelines. English language papers in PubMed were searched, with no date restrictions. In total, 1057 abstracts were screened, of which 602 were excluded owing to lack of appropriate controls, potential biases, and experimental design issues. The remaining 455 papers were independently reviewed by both authors and 108 studies were included in the final review. The authors met regularly to concur, through consensus, on relevance, methods, findings, quality, and conclusions. The included studies were published between 1979 and 2017. From the 108 included studies, 76 reported a favorable outcome of fermented milks on health and 67 of these were considered to be positive or neutral quality according to the Academy of Nutrition and Dietetics' Quality Criteria Checklist. Of the 32 remaining studies, the study outcomes were either not significant (28) or unfavorable (4), and most studies (18) were of neutral quality. A causal relationship exists between lactose digestion and tolerance and yogurt consumption, and consistent associations exist between fermented milk consumption and reduced risk of breast and colorectal cancer and type 2 diabetes, improved weight maintenance, and improved cardiovascular, bone, and gastrointestinal health. Further, an association exists between prostate cancer occurrence and dairy product consumption in general, with no difference between fermented and unfermented products. This article argues that yogurt and other fermented milk products provide favorable health outcomes beyond the milk from which these products are made and that consumption of these products should be encouraged as part of national dietary guidelines. Systematic review registration: PROSPERO registration no. CRD42017068953.
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The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue.
Lee, MC, Jhang, WL, Lee, CC, Kan, NW, Hsu, YJ, Ho, CS, Chang, CH, Cheng, YC, Lin, JS, Huang, CC
Metabolites. 2021;11(3)
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Compared to sedentary people, athletes exhibit a much more abundant and diverse composition of gut bacteria. Hence the relationship between gut microbes and energy usage and exercise performance has attracted much attention in recent years. Probiotics and prebiotic-related products have demonstrated the potential to enhance metabolic pathways and influence energy levels, energy consumption and exercise performance. And previous studies demonstrated positive effects on exercise endurance associated with the consumption of kefir, a fermented dairy product containing Lactobacilli species as part of the microbial symbiosis. This study investigated whether kefir can promote changes in the gut microbiota, improve exercise endurance performance, and influences fatigue during and after exercise. The study enrolled sixteen, untrained 20–30-year-old for a double-blind crossover design study, supplementing with SYNKEFIR™ for 28 days whilst observing changes in metabolic markers, body composition, exercise endurance and faecal gut bacteria. In summary, supplementation with SYNKEFIR™ significantly improved exercise performance and reduced the production of lactic acid after exercise. In addition, kefir supplementation seemed to reduce fatigue and accelerated the recovery from fatigue after exercise, with a marked reduction in lactic acid production after exercise. Though kefir supplementation had no significant effect on other post-exercise fatigue biochemical indicators nor did it induce notable changes in gut bacteria composition. As SYNKEFIR™ is a starter culture isolated from traditional kefir it could be expected that other traditional kefir products would have similar effects. Kefir as a food product is suited to a wide range of people, and it could be considered part of a healthy diet plan for untrained individuals wishing to support their exercise performance.
Abstract
Kefir is an acidic, carbonated, and fermented dairy product produced by fermenting milk with kefir grains. The Lactobacillus species constitutes an important part of kefir grains. In a previous animal study, kefir effectively improved exercise performance and had anti-fatigue effects. The purpose of this research was to explore the benefits of applying kefir to improve exercise performance, reduce fatigue, and improve physiological adaptability in humans. The test used a double-blind crossover design and supplementation for 28 days. Sixteen 20-30 year-old subjects were divided into two groups in a balanced order according to each individual's initial maximal oxygen uptake and were assigned to receive a placebo (equal flavor, equal calories, 20 g/day) or SYNKEFIR™ (20 g/day) every morning. After the intervention, there were 28 days of wash-out, during which time the subjects did not receive further interventions. After supplementation with SYNKEFIR™, the exercise time to exhaustion was significantly greater than that before ingestion (p = 0.0001) and higher than that in the Placebo group by 1.29-fold (p = 0.0004). In addition, compared with the Placebo group, the SYNKEFIR™ administration group had significantly lower lactate levels in the exercise and recovery (p < 0.05). However, no significant difference was observed in the changes in the gut microbiota. Although no significant changes in body composition were found, SYNKEFIR™ did not cause adverse reactions or harm to the participants' bodies. In summary, 28 days of supplementation with SYNKEFIR™ significantly improved exercise performance, reduced the production of lactic acid after exercise, and accelerated recovery while also not causing any adverse reactions.