Considerations for protein intake in managing weight loss in athletes

Associations Between Body Weight Dissatisfaction and Diet Quality in Women With a Body Mass Index in the Healthy Weight Category: Results From the 2014-2015 Swiss National Nutrition Survey

BACKGROUND

Few studies have examined whether diet quality is lower in women with body weight dissatisfaction compared with women without body weight dissatisfaction.

OBJECTIVES

(1) Examine the association between body weight dissatisfaction and diet quality among women (18-65 years old) in the healthy weight body mass index (BMI) category, and (2) explore dietary and behavioral patterns among women with body weight dissatisfaction.

DESIGN

Data were extracted from the cross-sectional 2014-2015 Swiss National Nutrition Survey.

PARTICIPANTS/SETTING

Population-based sample of 507 women with BMI ≥ 18.5 and < 25.

OUTCOME MEASURES

Dietary intakes assessed by registered dietitians using 2 nonconsecutive computer-assisted multi-pass 24-hour dietary recalls. Diet quality was measured with a slightly modified version of the Healthy Eating Index (HEI)-2020.

STATISTICAL ANALYSES PERFORMED

Multiple linear regressions were performed to test the association between body weight dissatisfaction and total HEI-2020 score. Hierarchical cluster analysis was used to identify subgroups of women with body weight dissatisfaction.

RESULTS

Body weight dissatisfaction was not found to be associated with diet quality (β = -1.73 [-4.18; 0.71], P = .16). However, women who were dissatisfied with their body weight had lower scores for the HEI-2020 total fruits (P = .050) and whole grains (P = .014) components than women who were satisfied with their body weight. Four profiles with different dietary patterns were identified among women with body weight dissatisfaction: "Unhealthy diet with dairy," "Protein and fat," "Vegetables without protein," and "Healthier diet without dairy."

CONCLUSIONS

Among women with a BMI in the healthy weight category, overall diet quality was not observed to differ between those with or without body weight dissatisfaction. More research is needed to explore the different profiles of dietary intake in women with body weight dissatisfaction.

Nutritional Considerations During Major Weight Loss Therapy: Focus on Optimal Protein and a Low-Carbohydrate Dietary Pattern

PURPOSE OF REVIEW

Considering the high prevalence of obesity and related metabolic impairments in the population, the unique role nutrition has in weight loss, reversing metabolic disorders, and maintaining health cannot be overstated. Normal weight and well-being are compatible with varying dietary patterns, but for the last half century there has been a strong emphasis on low-fat, low-saturated fat, high-carbohydrate based approaches. Whereas low-fat dietary patterns can be effective for a subset of individuals, we now have a population where the vast majority of adults have excess adiposity and some degree of metabolic impairment. We are also entering a new era with greater access to bariatric surgery and approval of anti-obesity medications (glucagon-like peptide-1 analogues) that produce substantial weight loss for many people, but there are concerns about disproportionate loss of lean mass and nutritional deficiencies.

RECENT FINDINGS

No matter the approach used to achieve major weight loss, careful attention to nutritional considerations is necessary. Here, we examine the recent findings regarding the importance of adequate protein to maintain lean mass, the rationale and evidence supporting low-carbohydrate and ketogenic dietary patterns, and the potential benefits of including exercise training in the context of major weight loss. While losing and sustaining weight loss has proven challenging, we are optimistic that application of emerging nutrition science, particularly personalized well-formulated low-carbohydrate dietary patterns that contain adequate protein (1.2 to 2.0 g per kilogram reference weight) and achieve the beneficial metabolic state of euketonemia (circulating ketones 0.5 to 5 mM), is a promising path for many individuals with excess adiposity.

Problems and Opportunities in the use of Bioelectrical Impedance Analysis for Assessing Body Composition During Ketogenic Diets: A Scoping Review

PURPOSE OF THE REVIEW

The use of bioelectrical impedance analysis (BIA) for monitoring body composition during the ketogenic diet has experienced a rapid surge. This scoping review aimed to assess the validity of procedures applying BIA in the ketogenic diet and to suggest best practices for optimizing its utilization.

RECENT FINDINGS

We conducted a systematic scoping review of peer-reviewed literature involving BIA for assessing body composition in individuals adhering to a ketogenic diet. Searches of international databases yielded 1609 unique records, 72 of which met the inclusion criteria and were reviewed. Thirty-five studies used foot-to-hand technology, 34 used standing position technology, while 3 did not declare the technology used. Raw bioelectrical parameters were reported in 21 studies. A total of 196 body mass components were estimated, but predictive equations were reported in only four cases. Most research on BIA during ketogenic diets did not report the equations used for predicting body composition, making it impossible to assess the validity of BIA outputs. Furthermore, the exceedingly low percentage of studies reporting and analyzing raw data makes it challenging to replicate methodologies in future studies, highlighting that BIA is not being utilized to its full potential. There is a need for more precise technology and device characteristics descriptions, full report of raw bioelectrical data, and predictive equations utilized. Moreover, evaluating raw data through vectorial analysis is strongly recommended. Eventually, we suggest best practices to enhance BIA outcomes during ketogenic diets.

Athletic bioimpedance-based equations underestimate fat free mass components in male elite soccer players: development and validation of new soccer-specific predictive models

BACKGROUND

Bioelectrical impedance analysis (BIA) is a rapid and user-friendly technique for assessing body composition in sports. Currently, no sport-specific predictive equations are available, and the utilization of generalized formulas can introduce systematic bias. The objectives of this study were as follows: (i) to develop and validate new predictive models for estimating fat-free mass (FFM) components in male elite soccer players; (ii) to evaluate the accuracy of existing predictive equations.

METHODS

A total of 102 male elite soccer players (mean age 24.7 ± 5.7 years), participating in the Italian first league, underwent assessments during the first half of the in-season period and were randomly divided into development and validation groups. Bioelectrical resistance (R) and reactance (Xc), representing the bioimpedance components, were measured using a foot-to-hand BIA device at a single frequency of 50 kHz. Dual-energy X-ray absorptiometry was employed to acquire reference data for FFM, lean soft tissue (LST), and appendicular lean soft tissue (ALST). The validation of the newly developed predictive equations was conducted through regression analysis, Bland-Altman tests, and the area under the curves (AUC) of regression receiver operating characteristic (RROC) curves.

RESULTS

Developed models were: FFM = - 7.729 + (body mass × 0.686) + (stature2/R × 0.227) + (Xc × 0.086) + (age × 0.058), R2 = 0.97, Standard error of estimation (SEE) = 1.0 kg; LST = - 8.929 + (body mass × 0.635) + (stature2/R × 0.244) + (Xc × 0.093) + (age × 0.048), R2 = 0.96, SEE = 0.9 kg; ALST = - 24.068 + (body mass × 0.347) + (stature2/R × 0.308) + (Xc × 0.152), R2 = 0.88, SEE = 1.4 kg. Train-test validation, performed on the validation group, revealed that generalized formulas for athletes underestimated all the predicted FFM components (p < 0.01), while the new predictive models showed no mean bias (p > 0.05), with R2 values ranging from 0.83 to 0.91, and no trend (p > 0.05). The AUC scores of the RROC curves indicated an accuracy of 0.92, 0.92, and 0.74 for FFM, LST, and ALST, respectively.

CONCLUSIONS

The utilization of generalized predictive equations leads to an underestimation of FFM and ALST in elite soccer players. The newly developed soccer-specific formulas enable valid estimations of body composition while preserving the portability of a field-based method.

Post-Exercise Protein Intake May Reduce Time in Hypoglycemia Following Moderate-Intensity Continuous Exercise among Adults with Type 1 Diabetes

Little is known about the role of post-exercise protein intake on post-exercise glycemia. Secondary analyses were conducted to evaluate the role of post-exercise protein intake on post-exercise glycemia using data from an exercise pilot study. Adults with T1D (n = 11), with an average age of 33.0 ± 11.4 years and BMI of 25.1 ± 3.4, participated in isoenergetic sessions of high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). Participants completed food records on the days of exercise and provided continuous glucose monitoring data throughout the study, from which time in range (TIR, 70-180 mg/dL), time above range (TAR, >180 mg/dL), and time below range (TBR, <70 mg/dL) were calculated from exercise cessation until the following morning. Mixed effects regression models, adjusted for carbohydrate intake, diabetes duration, and lean mass, assessed the relationship between post-exercise protein intake on TIR, TAR, and TBR following exercise. No association was observed between protein intake and TIR, TAR, or TBR (p-values ≥ 0.07); however, a borderline significant reduction of -1.9% (95% CI: -3.9%, 0.0%; p = 0.05) TBR per 20 g protein was observed following MICT in analyses stratified by exercise mode. Increasing post-exercise protein intake may be a promising strategy to mitigate the risk of hypoglycemia following MICT.

Bodybuilding Coaching Strategies Meet Evidence-Based Recommendations: A Qualitative Approach

Bodybuilding is a sport where coaches commonly recommend a variety of nutrition and exercise protocols, supplements, and, sometimes, performance-enhancing drugs (PEDs). The present study sought to gain an understanding of the common decisions and rationales employed by bodybuilding coaches. Focusing on coaches of the more muscular divisions in the National Physique Committee/IFBB Professional League federations (men's classic physique, men's bodybuilding, women's physique, women's bodybuilding) for both natural and enhanced athletes, coaches were recruited via word of mouth and social media, and 33 responded to an anonymous online survey. Survey responses indicated that participant coaches recommend three-to-seven meals per day and no less than 2 g/kg/day of protein regardless of sex, division, or PED usage. During contest preparation, participant coaches alter a natural competitor's protein intake by -25% to +10% and an enhanced competitor's protein intake by 0% to +25%. Regarding cardiovascular exercise protocols, approximately two-thirds of participant coaches recommend fasted cardiovascular exercise, with the common rationale of combining the exercise with thermogenic supplements while considering the athlete's preference. Low- and moderate-intensity steady state were the most commonly recommended types of cardiovascular exercise among participant coaches; high-intensity interval training was the least popular. Creatine was ranked in the top two supplements for all surveyed categories. Regarding PEDs, testosterone, growth hormone, and methenolone were consistently ranked in the top five recommended PEDs by participant coaches. The results of this study provide insight into common themes in the decisions made by bodybuilding coaches, and highlight areas in which more research is needed to empirically support those decisions.

Energy availability and macronutrient intake in elite male Gaelic football players

Evidence suggests that Gaelic football (GF) players do not meet the recommended energy intake (EI) levels and therefore may be at risk of low energy availability (LEA). This study examined energy availability (EA) in 20 elite male GF players. At two stages during a season (2019-2020), repeated measures of EI, exercise energy expenditure (EEE), EA and body composition were performed. Sixty-five percent reported with LEA [<30 kcal.kg Lean Body Mass (LBM)^-1.day^-1] at pre-season (PRE), with 70% at in-season (IN). Mean daily carbohydrate intake (PRE 3.2 ± 0.82 g.kg; IN 3.4 ± 0.79 g.kg) was below the recommended intake (5-7 g.kg) in 95% at PRE and 100% at IN. All consumed the recommended daily amount of protein (PRE 1.85 ± 0.57 g.kg; IN 1.87 ± 0.48 g.kg) and fat (PRE 1.23 ± 0.4 g.kg; IN 1.02 ± 0.3 g.kg). Significant correlations (P = 0.001) were reported between EA and carbohydrates (PRE r = 0.801; IN r = 0.714); protein (PRE r = 0.675; IN r = 0.769); fat (PRE r = 0.805; IN r = 0.733) and energy intake (PRE r = 0.960; IN r = 0.949). Twenty percent were at risk of disordered eating. This study suggests male elite GF players require education and interventions surrounding nutrition, in particular EA.

Life Cycle Environmental Impacts and Health Effects of Protein-Rich Food as Meat Alternatives: A Review

The food sector is responsible for a considerable impact on the environment in most environmental contexts: the food supply chain causes greenhouse gas emissions, water consumption, reduction in cultivable land, and other environmental impacts. Thus, a change in food supply is required to reduce the environmental impacts caused by the food supply chain and to meet the increasing demand for sufficient and qualitative nutrition. Large herds of livestock are inappropriate to achieve these goals due to the relevant impact of meat supply chain on the environment, e.g., the land used to grow feed for animals is eight times more than that for human nutrition. The search for meat alternatives, especially for the intake of critical nutrients such as protein, is a consequent step. In the above context, this paper summarizes the health aspects of protein-rich food alternatives to meat and carries out a literature review on the life-cycle environmental impacts of this alternative food.

Achieving an Optimal Fat Loss Phase in Resistance-Trained Athletes: A Narrative Review

Managing the body composition of athletes is a common practice in the field of sports nutrition. The loss of body weight (BW) in resistance-trained athletes is mainly conducted for aesthetic reasons (bodybuilding) or performance (powerlifting or weightlifting). The aim of this review is to provide dietary–nutritional strategies for the loss of fat mass in resistance-trained athletes. During the weight loss phase, the goal is to reduce the fat mass by maximizing the retention of fat-free mass. In this narrative review, the scientific literature is evaluated, and dietary–nutritional and supplementation recommendations for the weight loss phase of resistance-trained athletes are provided. Caloric intake should be set based on a target BW loss of 0.5–1.0%/week to maximize fat-free mass retention. Protein intake (2.2–3.0 g/kgBW/day) should be distributed throughout the day (3–6 meals), ensuring in each meal an adequate amount of protein (0.40–0.55 g/kgBW/meal) and including a meal within 2–3 h before and after training. Carbohydrate intake should be adapted to the level of activity of the athlete in order to training performance (2–5 g/kgBW/day). Caffeine (3–6 mg/kgBW/day) and creatine monohydrate (3–5 g/day) could be incorporated into the athlete’s diet due to their ergogenic effects in relation to resistance training. The intake of micronutrients complexes should be limited to special situations in which there is a real deficiency, and the athlete cannot consume through their diet.

High-Protein Energy-Restriction: Effects on Body Composition, Contractile Properties, Mood, and Sleep in Active Young College Students

Background: It is often advised to ensure a high-protein intake during energy-restricted diets. However, it is unclear whether a high-protein intake is able to maintain muscle mass and contractility in the absence of resistance training. Materials and Methods: After 1 week of body mass maintenance (45 kcal/kg), 28 male college students not performing resistance training were randomized to either the energy-restricted (ER, 30 kcal/kg, n = 14) or the eucaloric control group (CG, 45 kcal/kg, n = 14) for 6 weeks. Both groups had their protein intake matched at 2.8 g/kg fat-free-mass and continued their habitual training throughout the study. Body composition was assessed weekly using multifrequency bioelectrical impedance analysis. Contractile properties of the m. rectus femoris were examined with Tensiomyography and MyotonPRO at weeks 1, 3, and 5 along with sleep (PSQI) and mood (POMS). Results: The ER group revealed greater reductions in body mass (Δ -3.22 kg vs. Δ 1.90 kg, p < 0.001, partial η ² = 0.360), lean body mass (Δ -1.49 kg vs. Δ 0.68 kg, p < 0.001, partial η ² = 0.152), body cell mass (Δ -0.85 kg vs. Δ 0.59 kg, p < 0.001, partial η ² = 0.181), intracellular water (Δ -0.58 l vs. Δ 0.55 l, p < 0.001, partial η ² = 0.445) and body fat percentage (Δ -1.74% vs. Δ 1.22%, p < 0.001, partial η ² = 433) compared to the CG. Contractile properties, sleep onset, sleep duration as well as depression, fatigue and hostility did not change (p > 0.05). The PSQI score (Δ -1.43 vs. Δ -0.64, p = 0.006, partial η ² = 0.176) and vigor (Δ -2.79 vs. Δ -4.71, p = 0.040, partial η ² = 0.116) decreased significantly in the ER group and the CG, respectively. Discussion: The present data show that a high-protein intake alone was not able to prevent lean mass loss associated with a 6-week moderate energy restriction in college students. Notably, it is unknown whether protein intake at 2.8 g/kg fat-free-mass prevented larger decreases in lean body mass. Muscle contractility was not negatively altered by this form of energy restriction. Sleep quality improved in both groups. Whether these advantages are due to the high-protein intake cannot be clarified and warrants further study. Although vigor was negatively affected in both groups, other mood parameters did not change.

Effect of a Food for Special Medical Purposes for Muscle Recovery, Consisting of Arginine, Glutamine and Beta-Hydroxy-Beta-Methylbutyrate on Body Composition and Skin Health in Overweight and Obese Class I Sedentary Postmenopausal Women

The consumption of dietary amino acids has been evaluated for therapeutic and safety intervention in obesity. In particular, three molecules have been shown to be effective: arginine, glutamine and leucine (and its metabolite beta-hydroxy-beta-methylbutyrate, HMB). This randomized, double-blinded pilot study in obese postmenopausal patients aimed to evaluate the efficacy of the administration of a specific food for special medical purposes (FSMP) consisting of arginine, glutamine and HMB on body composition, in particular, visceral adipose tissue (VAT), assessed by dual-energy X-ray absorptiometry (DXA), as the primary endpoint. The secondary endpoint was to evaluate the effects on skin health through a validated self-reported questionnaire. A significant improvement on VAT of Δ = -153.600, p = 0.01 was recorded in the intervention group. Skin health showed a significant improvement in the treatment group for the following: bright Δ = 1.400 (0.758; 2.042), elasticity Δ = 0.900 (0.239; 1.561), wrinkles Δ = 0.800 (0.276; 1.324), and on total score, Δ = 3.000 (1.871; 4.129). In the intervention group, the improvement in VAT was associated with an improvement in the bright score (r = -0.58; p = 0.01). In conclusion, this study demonstrated that the intake for 4-weeks of arginine, glutamine and HMB effects a significant reduction in VAT and improves skin condition, while fat free mass (FFM) is maintained, thus achieving "high-quality" weight loss.

Metabolic Adaptations to Weight Loss: A Brief Review

ABSTRACT

Martínez-Gómez, MG and Roberts, BM. Metabolic adaptations to weight loss: A brief review. J Strength Cond Res XX(X): 000-000, 2021-As the scientific literature has continuously shown, body mass loss attempts do not always follow a linear fashion nor always go as expected even when the intervention is calculated with precise tools. One of the main reasons why this tends to happen relies on our body's biological drive to regain the body mass we lose to survive. This phenomenon has been referred to as "metabolic adaptation" many times in the literature and plays a very relevant role in the management of obesity and human weight loss. This review will provide insights into some of the theoretical models for the etiology of metabolic adaptation as well as a quick look into the physiological and endocrine mechanisms that underlie it. Nutritional strategies and dietetic tools are thus necessary to confront these so-called adaptations to body mass loss. Among some of these strategies, we can highlight increasing protein needs, opting for high-fiber foods or programming-controlled diet refeeds, and diet breaks over a large body mass loss phase. Outside the nutritional aspects, it might be wise to increase the physical activity and thus the energy flux of an individual when possible to maintain diet-induced body mass loss in the long term. This review will examine these protocols and their viability in the context of adherence and sustainability for the individual toward successful body mass loss.

Type 1 Diabetes and Physical Exercise: Moving (forward) as an Adjuvant Therapy

Type 1 diabetes is characterized by an autoimmune β-cell destruction resulting in endogenous insulin deficiency, potentially leading to micro- and macrovascular complications. Besides an exogenous insulin therapy and continuous glucose monitoring, physical exercise is recommended in adults with type 1 diabetes to improve overall health. The close relationship between physical exercise, inflammation, muscle contraction, and macronutrient intake has never been discussed in detail about type 1 diabetes. The aim of this narrative review was to detail the role of physical exercise in improving clinical outcomes, physiological responses to exercise and different nutrition and therapy strategies around exercise. Physical exercise has several positive effects on glucose uptake and systemic inflammation in adults with type 1 diabetes. A new approach via personalized therapy adaptations must be applied to target beneficial effects on complications as well as on body weight management. In combination with pre-defined macronutrient intake around exercise, adults with type 1 diabetes can expect similar physiological responses to physical exercise, as seen in their healthy counterparts. This review highlights interesting findings from recent studies related to exercise and type 1 diabetes. However, there is limited research available accompanied by a proper number of participants in the cohort of type 1 diabetes. Especially for this group of patients, an increased understanding of the impact of physical exercise can improve its effectiveness as an adjuvant therapy to move (forward).

UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a 'food first' philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

Maximizing Post-exercise Anabolism: The Case for Relative Protein Intakes

Maximizing the post-exercise increase in muscle protein synthesis, especially of the contractile myofibrillar protein fraction, is essential to facilitate effective muscle remodeling, and enhance hypertrophic gains with resistance training. MPS is the primary regulated variable influencing muscle net balance with dietary amino acid ingestion representing the single most important nutritional variable enhancing post-exercise rates of muscle protein synthesis. Dose-response studies in average (i.e., ~80 kg) males have reported an absolute 20 g dose of high quality, rapidly digested protein maximizes mixed, and myofibrillar protein synthetic rates. However, it is unclear if these absolute protein intakes can be viewed in a “one size fits all” solution. Re-analysis of published literature in young adults suggests a relative single meal intake of ~0.31 g/kg of rapidly digested, high quality protein (i.e., whey) should be considered as a nutritional guideline for individuals of average body composition aiming to maximize post-exercise myofibrillar protein synthesis while minimizing irreversible amino acid oxidative catabolism that occurs with excessive intakes of this macronutrient. This muscle-specific bolus intake is lower than that reported to maximize whole body anabolism (i.e., ≥0.5 g/kg). Review of the available literature suggests that potential confounders such as the co-ingestion of carbohydrate, sex, and amount of active muscle mass do not represent significant barriers to the translation of this objectively determined relative protein intake. Additional research is warranted to elucidate the effective dose for proteins with suboptimal amino acid compositions (e.g., plant-based), and/or slower digestion rates as well as whether recommendations are appreciably affected by other physiological conditions such endurance exercise, high habitual daily protein ingestion, aging, obesity, and/or periods of chronic negative energy balance.

Comparative Meta-Analysis of the Effect of Concentrated, Hydrolyzed, and Isolated Whey Protein Supplementation on Body Composition of Physical Activity Practitioners

Whey protein (WP) is a dairy food supplement and, due to its effects on fat-free mass (FFM) gain and fat mass (FM) loss, it has been widely consumed by resistance training practitioners. This review analyzed the impact of WP supplementation in its concentrated (WPC), hydrolyzed (WPH) and isolated (WPI) forms, comparing it exclusively to isocaloric placebos. Random effect meta-analyses were performed from the final and initial body composition values of 246 healthy athletes undergoing 64.5 ± 15.3 days of training in eight randomized clinical trials (RCT) collected systematically from five scientific databases. The weighted mean difference (WMD) was statistically significant for FM loss (WMD = −0.96, 95% CI = −1.37, −0.55, p < 0.001) and, in the analysis of subgroups, this effect was maintained for the WPC (WMD = −0.63, 95% CI = −1.19, −0.06, p = 0.030), with protein content between 51% and 80% (WMD = −1.53; 95% CI = −2.13, −0.93, p < 0.001), and only for regular physical activity practitioners (WMD = −0.95; 95% CI = −1.70, −0.19, p = 0.014). There was no significant effect on FFM in any of the scenarios investigated (p > 0.05). Due to several and important limitations, more detailed analyses are required regarding FFM gain.

Association of Protein Intake in Three Meals with Muscle Mass in Healthy Young Subjects: A Cross-Sectional Study

Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has not been evaluated. We hypothesized that a protein intake of >0.24 g/kg BW at all three meals is effective for maintaining muscle mass. Therefore, we cross-sectionally examined the association between protein intake at all three meals with muscle mass in 266 healthy young subjects (aged 21.4 ± 2.4 years). Subjects were divided into the AP group, which achieved protein intake >0.24 g/kg BW at all three meals; and the NP group, which did not. We calculated total fat-free mass (FFM) and appendicular fat-free mass (AppFFM) with dual-energy X-ray absorptiometry, and the percentage of total FFM (TotalFFM%) and appendicular FFM (AppFFM%) were calculated as the percentage of BW (%BW). We demonstrated that TotalFFM% (77.0 ± 0.5 vs. 75.2 ± 0.4%, p = 0.008) and AppFFM% (34.7 ± 0.3 vs. 34.1 ± 0.2%, p = 0.058) were higher in the AP than in the NP group. This finding suggests that achieving protein intake of >0.24 g/kg BW at all three meals is important for muscle mass maintenance in young populations.

Nutritional Considerations for Sport Participation in Children and Adolescents With Obesity

There is a high prevalence of children with obesity who are participating in sports. Appropriate nutritional considerations are important to optimize health and training adaptations. This review focuses on macronutrient recommendations and their effect on weight management and/or benefits for athletic training for children ages 5 to 18 years. Equal distribution of protein intake throughout the day (~25-30 g/meal) and during postexercise recovery is recommended. Special attention should be given to increasing protein intake during breakfast because it is often the meal with the least protein intake. Both postexercise recommendations for protein (~0.3 g/kg of body weight) and carbohydrate (~1.0-1.2 g/kg/h) were not determined in children with obesity, and require future verification. Individual carbohydrate needs of training to meet fuel costs are recommended, but ~200 to 500 g/day of carbohydrate may be required depending on a child's level of sport participation and competition. Fat intake should follow general recommendations to meet the accepted macronutrient distribution range in children (25% to 35%) and reduce saturated fat intake. No evidence suggests that additional dietary fat modifications would improve training adaptations in children. Longitudinal studies are required to further our understanding of age and sex effects and confirm the appropriate quantity of macronutrients for active children with obesity.

Dietary Protein for Training Adaptation and Body Composition Manipulation in Track and Field Athletes

Track and field athletes engage in vigorous training that places stress on physiological systems requiring nutritional support for optimal recovery. Of paramount importance when optimizing recovery nutrition are rehydration and refueling which are covered in other papers in this volume. Here, we highlight the benefits for dietary protein intake over and above requirements set out in various countries at ∼0.8-1.0 g·kg body mass (BM)^-1·day^-1 for training adaptation, manipulating body composition, and optimizing performance in track and field athletes. To facilitate the remodeling of protein-containing structures, which are turning over rapidly due to their training volumes, track and field athletes with the goal of weight maintenance or weight gain should aim for protein intakes of ∼1.6 g·kg BM^-1·day^-1. Protein intakes at this level would not necessarily require an overemphasis on protein-containing foods and, beyond convenience, does not suggest a need to use protein or amino acid-based supplements. This review also highlights that optimal protein intakes may exceed 1.6 g·kg BM^-1·day^-1 for athletes who are restricting energy intake and attempting to minimize loss of lean BM. We discuss the underpinning rationale for weight loss in track and field athletes, explaining changes in metabolic pathways that occur in response to energy restriction when manipulating protein intake and training. Finally, this review offers practical advice on protein intakes that warrant consideration in allowing an optimal adaptive response for track and field athletes seeking to train effectively and to lose fat mass while energy restricted with minimal (or no) loss of lean BM.

Effect of a Whey Protein Supplement on Preservation of Fat Free Mass in Overweight and Obese Individuals on an Energy Restricted Very Low Caloric Diet

The obesity epidemic has caused a widespread interest in strategies to achieve a healthy "high quality" weight loss, where excess fat is lost, while fat free mass (FFM) is preserved. In this study, we aimed to examine the effect of whey protein supplementation given before night sleep on FFM preservation during a 4-week (wk) period on a very low caloric diet (VLCD). Twenty-nine obese subjects (body mass index (BMI) > 28 kg/m²) completed a 4-week intervention including a VLCD and a walking program (30 min walking × 5 times per week). Subjects were randomly assigned to either control (CON, n = 15) or a whey protein supplement (PRO, 0.4 g protein/kg/day, n = 14), ingested before bedtime. Body composition (dual-energy X-ray absorptiometry, DXA), blood analysis and physical test were performed pre and post intervention. We measured nitrogen excretion in three 24 h urine collections (Day 0, 7 and 28) to assess nitrogen balance. Changes in nitrogen balance (NB) after 7 and 28 days was different between treatment groups (interaction p < 0.05). PRO was in NB after 7 days and in positive NB at day 28. In contrast, CON was in negative NB at day 7, but in NB at day 28. Nevertheless, no significant group differences were observed in the change in pre- and post-FFM measurements (-2.5 kg, [95% CI: 1.9; 3.1], p = 0.65). In conclusion, ingestion of a whey protein supplement before bedtime during a 4-week period on a VLCD improved nitrogen balance, but did not lead to any significant improvement in the quality of the weight loss in regard to observed changes in body composition and health parameters compared with controls.

Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance

There exists a large body of scientific evidence to support protein intakes in excess of the recommended dietary allowance (RDA) (0.8 g protein/kg/day) to promote the retention of skeletal muscle and loss of adipose tissue during dietary energy restriction. Diet-induced weight loss with as low as possible ratio of skeletal muscle to fat mass loss is a situation we refer to as high-quality weight loss. We propose that high-quality weight loss is often of importance to elite athletes in order to maintain their muscle (engine) and shed unwanted fat mass, potentially improving athletic performance. Current recommendations for protein intakes during weight loss in athletes are set at 1.6-2.4 g protein/kg/day. However, the severity of the caloric deficit and type and intensity of training performed by the athlete will influence at what end of this range athletes choose to be. Other considerations regarding protein intake that may help elite athletes achieve weight loss goals include the quality of protein consumed, and the timing and distribution of protein intake throughout the day. This review highlights the scientific evidence used to support protein recommendations for high-quality weight loss and preservation of performance in athletes. Additionally, the current knowledge surrounding the use of protein supplements, branched chain amino acids (BCAA), β-hydroxy β-methylbutyrate (HMB), and other dietary supplements with weight loss claims will be discussed.

Pronounced energy restriction with elevated protein intake results in no change in proteolysis and reductions in skeletal muscle protein synthesis that are mitigated by resistance exercise

Preservation of lean body mass (LBM) may be important during dietary energy restriction (ER) and requires equal rates of muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Currently, the relative contribution of MPS and MPB to the loss of LBM during ER in humans is unknown. We aimed to determine the impact of dietary protein intake and resistance exercise on MPS and MPB during a controlled short-term energy deficit. Adult men (body mass index, 28.6 ± 0.6 kg/m²; age 22 ± 1 yr) underwent 10 d of 40%-reduced energy intake while performing unilateral resistance exercise and consuming lower protein (1.2 g/kg/d, n = 12) or higher protein (2.4 g/kg/d, n = 12). Pre- and postintervention testing included dual-energy X-ray absorptiometry, primed constant infusion of ring-[¹³C₆]phenylalanine, and ¹⁵[N]phenylalanine to measure acute postabsorptive MPS and MPB; D₂O to measure integrated MPS; and gene and protein expression. There was a decrease in acute MPS after ER (higher protein, 0.059 ± 0.006 to 0.051 ± 0.009%/h; lower protein, 0.061 ± 0.005 to 0.045 ± 0.006%/h; P < 0.05) that was attenuated with resistance exercise (higher protein, 0.067 ± 0.01%/h; lower protein, 0.061 ± 0.006%/h), and integrated MPS followed a similar pattern. There was no change in MPB (energy balance, 0.080 ± 0.01%/hr; ER rested legs, 0.078 ± 0.008%/hr; ER exercised legs, 0.079 ± 0.006%/hr). We conclude that a reduction in MPS is the main mechanism that underpins LBM loss early in ER in adult men.-Hector, A. J., McGlory, C., Damas, F., Mazara, N., Baker, S. K., Phillips, S. M. Pronounced energy restriction with elevated protein intake results in no change in proteolysis and reductions in skeletal muscle protein synthesis that are mitigated by resistance exercise.

Exercise management in type 1 diabetes: a consensus statement

Type 1 diabetes is a challenging condition to manage for various physiological and behavioural reasons. Regular exercise is important, but management of different forms of physical activity is particularly difficult for both the individual with type 1 diabetes and the health-care provider. People with type 1 diabetes tend to be at least as inactive as the general population, with a large percentage of individuals not maintaining a healthy body mass nor achieving the minimum amount of moderate to vigorous aerobic activity per week. Regular exercise can improve health and wellbeing, and can help individuals to achieve their target lipid profile, body composition, and fitness and glycaemic goals. However, several additional barriers to exercise can exist for a person with diabetes, including fear of hypoglycaemia, loss of glycaemic control, and inadequate knowledge around exercise management. This Review provides an up-to-date consensus on exercise management for individuals with type 1 diabetes who exercise regularly, including glucose targets for safe and effective exercise, and nutritional and insulin dose adjustments to protect against exercise-related glucose excursions.

Metabolic advantages of higher protein diets and benefits of dairy foods on weight management, glycemic regulation, and bone

The Inst. of Medicine and World Health Organization have determined that 0.8 to 0.83 g protein·kg(-1) ·d(-1) is the quantity of protein required to establish nitrogen balance in nearly all healthy individuals. However, consuming higher protein diets may be metabolically advantageous, particularly for overweight and obese adults attempting weight loss, and for physically active individuals such as athletes and military personnel. Studies have demonstrated that higher protein diets may spare lean body mass during weight loss, promote weight management, enhance glycemic regulation, and increase intestinal calcium absorption, which may result in long-term improvements in bone health. The extent to which higher protein diets are beneficial is largely attributed to the digestive and absorptive properties, and also to the essential amino acid (EAA) content of the protein. Proteins that are rapidly digested and absorbed likely contribute to the metabolic advantages conferred by consuming higher protein diets. The EAA profiles, as well as the digestive and absorptive properties of dairy proteins, such as whey protein and casein, are particularly advantageous because they facilitate a rapid, robust, and sustained delivery of EAAs to the periphery. This article reviews the scientific literature assessing metabolic advantages associated with higher protein diets on weight management, glycemic regulation, and bone, with emphasis given to studies evaluating the potential benefits associated with dairy.

Nutritional Considerations for Performance in Young Athletes

Nutrition is an integral component to any athletes training and performance program. In adults the balance between energy intake and energy demands is crucial in training, recovery, and performance. In young athletes the demands for training and performance remain but should be a secondary focus behind the demands associated with maintaining the proper growth and maturation. Research interventions imposing significant physiological loads and diet manipulation are limited in youth due to the ethical considerations related to potential negative impacts on the growth and maturation processes associated with younger individuals. This necessary limitation results in practitioners providing nutritional guidance to young athletes to rely on exercise nutrition recommendations intended for adults. While many of the recommendations can appropriately be repurposed for the younger athlete attention needs to be taken towards the differences in metabolic needs and physiological differences.

A nutrition and conditioning intervention for natural bodybuilding contest preparation: case study

Bodybuilding competitions are becoming increasingly popular. Competitors are judged on their aesthetic appearance and usually exhibit a high level of muscularity and symmetry and low levels of body fat. Commonly used techniques to improve physique during the preparation phase before competitions include dehydration, periods of prolonged fasting, severe caloric restriction, excessive cardiovascular exercise and inappropriate use of diuretics and anabolic steroids. In contrast, this case study documents a structured nutrition and conditioning intervention followed by a 21 year-old amateur bodybuilding competitor to improve body composition, resting and exercise fat oxidation, and muscular strength that does not involve use of any of the above mentioned methods. Over a 14-week period, the Athlete was provided with a scientifically designed nutrition and conditioning plan that encouraged him to (i) consume a variety of foods; (ii) not neglect any macronutrient groups; (iii) exercise regularly but not excessively and; (iv) incorporate rest days into his conditioning regime. This strategy resulted in a body mass loss of 11.7 kg’s, corresponding to a 6.7 kg reduction in fat mass and a 5.0 kg reduction in fat-free mass. Resting metabolic rate decreased from 1993 kcal/d to 1814 kcal/d, whereas resting fat oxidation increased from 0.04 g/min to 0.06 g/min. His capacity to oxidize fat during exercise increased more than two-fold from 0.24 g/min to 0.59 g/min, while there was a near 3-fold increase in the corresponding exercise intensity that elicited the maximal rate of fat oxidation; 21% V̇O_2max to 60% V̇O_2max. Hamstring concentric peak torque decreased (1.7 to 1.5 Nm/kg), whereas hamstring eccentric (2.0 Nm/kg to 2.9 Nm/kg), quadriceps concentric (3.4 Nm/kg to 3.7 Nm/kg) and quadriceps eccentric (4.9 Nm/kg to 5.7 Nm/kg) peak torque all increased. Psychological mood-state (BRUMS scale) was not negatively influenced by the intervention and all values relating to the Athlete’s mood-state remained below average over the course of study. This intervention shows that a structured and scientifically supported nutrition strategy can be implemented to improve parameters relevant to bodybuilding competition and importantly the health of competitors, therefore questioning the conventional practices of bodybuilding preparation.