Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial
TL;DR: It is determined that consuming dietary protein at levels exceeding the RDA may protect fat‐free mass during short‐term weight loss and muscle protein synthesis following weight loss.
Abstract: The purpose of this work was to determine the effects of varying levels of dietary protein on body composition and muscle protein synthesis during energy deficit (ED). A randomized controlled trial of 39 adults assigned the subjects diets providing protein at 0.8 (recommended dietary allowance; RDA), 1.6 (2×-RDA), and 2.4 (3×-RDA) g kg(-1) d(-1) for 31 d. A 10-d weight-maintenance (WM) period was followed by a 21 d, 40% ED. Body composition and postabsorptive and postprandial muscle protein synthesis were assessed during WM (d 9-10) and ED (d 30-31). Volunteers lost (P 0.05) from WM for 2×-RDA and 3×-RDA, but was lower during ED than WM for those consuming RDA levels of protein (energy × protein interaction, P<0.05). To assess muscle protein metabolic responses to varied protein intakes during ED, RDA served as the study control. In summary, we determined that consuming dietary protein at levels exceeding the RDA may protect fat-free mass during short-term weight loss.
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TL;DR: The evolution, controversies and challenges in defining sarcopenic obesity are discussed, and current body composition modalities used to assess this condition are presented and current treatment strategies are outlined.
Abstract: The prevalence of obesity in combination with sarcopenia (the age-related loss of muscle mass and strength or physical function) is increasing in adults aged 65 years and older. A major subset of adults over the age of 65 is now classified as having sarcopenic obesity, a high-risk geriatric syndrome predominantly observed in an ageing population that is at risk of synergistic complications from both sarcopenia and obesity. This Review discusses pathways and mechanisms leading to muscle impairment in older adults with obesity. We explore sex-specific hormonal changes, inflammatory pathways and myocellular mechanisms leading to the development of sarcopenic obesity. We discuss the evolution, controversies and challenges in defining sarcopenic obesity and present current body composition modalities used to assess this condition. Epidemiological surveys form the basis of defining its prevalence and consequences beyond comorbidity and mortality. Current treatment strategies, and the evidence supporting them, are outlined, with a focus on calorie restriction, protein supplementation and aerobic and resistance exercises. We also describe weight loss-induced complications in patients with sarcopenic obesity that are relevant to clinical management. Finally, we review novel and potential future therapies including testosterone, selective androgen receptor modulators, myostatin inhibitors, ghrelin analogues, vitamin K and mesenchymal stem cell therapy.
756 citations
TL;DR: This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.
Abstract: Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words ‘sport nutrition’. Consequently, staying current with the relevant literature is often difficult. This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches. This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.
404 citations
TL;DR: Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day.
Abstract: Importance The efficacy and safety of time-restricted eating have not been explored in large randomized clinical trials. Objective To determine the effect of 16:8-hour time-restricted eating on weight loss and metabolic risk markers. Interventions Participants were randomized such that the consistent meal timing (CMT) group was instructed to eat 3 structured meals per day, and the time-restricted eating (TRE) group was instructed to eatad libitumfrom 12:00pmuntil 8:00pmand completely abstain from caloric intake from 8:00pmuntil 12:00pmthe following day. Design, Setting, and Participants This 12-week randomized clinical trial including men and women aged 18 to 64 years with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) of 27 to 43 was conducted on a custom mobile study application. Participants received a Bluetooth scale. Participants lived anywhere in the United States, with a subset of 50 participants living near San Francisco, California, who underwent in-person testing. Main Outcomes and Measures The primary outcome was weight loss. Secondary outcomes from the in-person cohort included changes in weight, fat mass, lean mass, fasting insulin, fasting glucose, hemoglobin A1clevels, estimated energy intake, total energy expenditure, and resting energy expenditure. Results Overall, 116 participants (mean [SD] age, 46.5 [10.5] years; 70 [60.3%] men) were included in the study. There was a significant decrease in weight in the TRE (−0.94 kg; 95% CI, −1.68 to −0.20;P = .01), but no significant change in the CMT group (−0.68 kg; 95% CI, -1.41 to 0.05,P = .07) or between groups (−0.26 kg; 95% CI, −1.30 to 0.78;P = .63). In the in-person cohort (n = 25 TRE, n = 25 CMT), there was a significant within-group decrease in weight in the TRE group (−1.70 kg; 95% CI, −2.56 to −0.83;P Conclusions and Relevance Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day. Trial Registration ClinicalTrials.gov Identifiers:NCT03393195andNCT03637855
219 citations
TL;DR: Results showed that, during a marked energy deficit, consumption of a diet containing 2.4 g protein was more effective in promoting increases in LBM and losses of fat mass when combined with a high volume of resistance and anaerobic exercise.
176 citations
Cites background or result from "Effects of high-protein diets on fa..."
...We propose that the disparate findings of the previous study (4) and our findings may be due to the timing of our supplementation and the exercise intensity, which could be important in increasing or maintaining LBM while in a severe energy deficit (3)....
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...Combining a higher protein intake with RT during caloric restriction would act synergistically on the rates of MPS, resulting in a greater ratio of fat to LBM lost during energy restriction (5, 6), which may be advantageous for physical performance....
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...The data from Areta et al. (3) do show that, while in an energy deficit, larger protein doses .0.25 g $ kg21 per meal continued to stimulate MPS after resistance exercise....
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...It is more than likely, however, that our results were due as much, if not more, to the addition of resistance exercise, which acts synergistically to stimulate MPS even in an energy deficit (3)....
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...(4) reported that daily protein at twice the Recommended Dietary Allowance (RDA) for protein attenuated the loss of LBM during an energy deficit with both aerobic and resistance exercise....
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TL;DR: It was hypothesized that TRE facilitates weight loss, alters body composition, and improves metabolic measures and may be an option for treating obesity.
Abstract: Objective In contrast to intentionally restricting energy intake, restricting the eating window may be an option for treating obesity. By comparing time-restricted eating (TRE) with an unrestricted (non-TRE) control, it was hypothesized that TRE facilitates weight loss, alters body composition, and improves metabolic measures. Methods Participants (17 women and 3 men; mean [SD]: 45.5 [12.1] years; BMI 34.1 [7.5] kg/m2 ) with a prolonged eating window (15.4 [0.9] hours) were randomized to TRE (n = 11: 8-hour window, unrestricted eating within window) versus non-TRE (n = 9: unrestricted eating) for 12 weeks. Weight, body composition (dual x-ray absorptiometry), lipids, blood pressure, 2-hour oral glucose tolerance, 2-week continuous glucose monitoring, and 2-week physical activity (actigraphy assessed) were measured during the pre- and end-intervention periods. Results The TRE group significantly reduced the eating window (end-intervention window: 9.9 [2.0] hours) compared with the non-TRE group (end-intervention window: 15.1 [1.1] hours) (P Conclusions In the setting of a randomized trial, TRE presents a simplified view of food intake that reduces weight.
161 citations
References
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TL;DR: This protocol provides an overview of the comparative CT method for quantitative gene expression studies and various examples to present quantitative gene Expression data using this method.
Abstract: Two different methods of presenting quantitative gene expression exist: absolute and relative quantification. Absolute quantification calculates the copy number of the gene usually by relating the PCR signal to a standard curve. Relative gene expression presents the data of the gene of interest relative to some calibrator or internal control gene. A widely used method to present relative gene expression is the comparative C(T) method also referred to as the 2 (-DeltaDeltaC(T)) method. This protocol provides an overview of the comparative C(T) method for quantitative gene expression studies. Also presented here are various examples to present quantitative gene expression data using this method.
20,580 citations
"Effects of high-protein diets on fa..." refers methods in this paper
...Expression data are presented as fold change compared to WM, postabsorptive RDA using the 2 Ct method (29)....
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TL;DR: An updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure, is provided to enhance the comparability of results across studies using self-reports of PA.
Abstract: We provide an updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure. It was developed to enhance the comparability of results across studies using self-reports of PA. The Compendium coding scheme links a five-digit code that describes physical activities by major headings (e.g., occupation, transportation, etc.) and specific activities within each major heading with its intensity, defined as the ratio of work metabolic rate to a standard resting metabolic rate (MET). Energy expenditure in MET-minutes, MET-hours, kcal, or kcal per kilogram body weight can be estimated for specific activities by type or MET intensity. Additions to the Compendium were obtained from studies describing daily PA patterns of adults and studies measuring the energy cost of specific physical activities in field settings. The updated version includes two new major headings of volunteer and religious activities, extends the number of specific activities from 477 to 605, and provides updated MET intensity levels for selected activities.
7,872 citations
"Effects of high-protein diets on fa..." refers background in this paper
...3 to account for activities of daily living and diet-induced thermogenesis, and 7-d physical activity records to estimate energy expended during physical activity (20)....
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5,415 citations
TL;DR: In 2009-2010, the prevalence of obesity was 35.5% among adult men and 35.8% amongadult women, with no significant change compared with 2003-2008, and trends in BMI were similar to obesity trends.
Abstract: Results In 2009-2010 the age-adjusted mean BMI was 28.7 (95% CI, 28.3-29.1) for men and also 28.7 (95% CI, 28.4-29.0) for women. Median BMI was 27.8 (interquartile range [IQR], 24.7-31.7) for men and 27.3 (IQR, 23.3-32.7) for women. The age-adjusted prevalence of obesity was 35.5% (95% CI, 31.9%-39.2%) among adult men and 35.8% (95% CI, 34.0%-37.7%) among adult women. Over the 12-year period from 1999 through 2010, obesity showed no significant increase among women overall (age- and race-adjusted annual change in odds ratio [AOR], 1.01; 95% CI, 1.00-1.03; P=.07), but increases were statistically significant for non-Hispanic black women (P=.04) and Mexican American women (P=.046). For men, there was a significant linear trend (AOR, 1.04; 95% CI, 1.02-1.06; P.001) over the 12-year period. For both men and women, the most recent 2 years (2009-2010) did not differ significantly (P=.08 for men and P=.24 for women) from the previous 6 years (20032008). Trends in BMI were similar to obesity trends.
5,333 citations
"Effects of high-protein diets on fa..." refers background in this paper
...Given the prevalence of obesity (32), and the pro-...
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