Substantial evidence supports the increased consumption of high-quality protein to achieve optimal health outcomes. A growing body of research indicates that protein intakes well above the current Recommended Dietary Allowance help to promote healthy aging, appetite regulation, weight management, and goals aligned with athletic performance. Higher protein intakes may help prevent age-related sarcopenia, the loss of muscle mass, and strength that predisposes older adults to frailty, disability, and loss of autonomy. Higher protein diets also improve satiety and lead to greater reductions in body weight and fat mass compared with standard protein diets, and may therefore serve as a successful strategy to help prevent and/or treat obesity. Athletes can also benefit from higher protein intakes to maximize athletic performance given the critical role protein plays in stimulating muscle protein remodelling after exercise. Protein quality, per meal dose, and timing of ingestion are also important considerations. Despite persistent beliefs to the contrary, we can find no evidence-based link between higher protein diets and renal disease or adverse bone health. This brief synopsis highlights recent learnings based on presentations at the 2015 Canadian Nutrition Society conference, Advances in Protein Nutrition across the Lifespan. Current evidence indicates intakes in the range of at least 1.2 to 1.6 g/(kg·day) of high-quality protein is a more ideal target for achieving optimal health outcomes in adults.Key words: protein, protein recommendations, protein quality, sarcopenia, elderly, weight management, obesity, muscle, athletes, exercise, satiety.Résumé : Beaucoup d'études probantes appuient la thèse selon laquelle l'augmentation de la consommation de protéines de haute qualité améliore la santé. De plus en plus d'études rapportent qu'une consommation de protéines bien supérieure aux rations alimentaires recommandées favorise le vieillissement en santé, la régulation de l'appétit, le contrôle du poids et les objectifs en matière de performance sportive. Une plus grande consommation de protéines pourrait prévenir la sarcopénie associée à l'âge, la perte de masse musculaire et de force musculaire qui prédispose les personnes âgées à la fragilité, l'incapacité et la perte de l'autonomie. Un régime alimentaire riche en protéines améliore la satiété et favorise une plus grande diminution de la masse corporelle et graisseuse comparativement aux régimes protéiques standards et pourrait constituer une stratégie gagnante pour la prévention et le traitement de l'obésité. Les athlètes ont aussi à gagner en consommant plus de protéines afin de maximiser leur performance sportive compte tenu du rôle essentiel des protéines dans la stimulation du remodelage des protéines musculaires à la suite de l'exercice physique. La qualité des protéines, la dose par repas et le moment de la consommation sont aussi à prendre en compte. Malgré les croyances ancrées du contraire, on ne trouve aucune donnée probante présentant une associa...

Over the past 20 y, higher-protein diets have been touted as a successful strategy to prevent or treat obesity through improvements in body weight management. These improvements are thought to be due, in part, to modulations in energy metabolism, appetite, and energy intake. Recent evidence also supports higher-protein diets for improvements in cardiometabolic risk factors. This article provides an overview of the literature that explores the mechanisms of action after acute protein consumption and the clinical health outcomes after consumption of long-term, higher-protein diets. Several meta-analyses of shorter-term, tightly controlled feeding studies showed greater weight loss, fat mass loss, and preservation of lean mass after higherprotein energy-restriction diets than after lower-protein energyrestriction diets. Reductions in triglycerides, blood pressure, and waist circumference were also reported. In addition, a review of the acute feeding trials confirms a modest satiety effect, including greater perceived fullness and elevated satiety hormones after higherprotein meals but does not support an effect on energy intake at the next eating occasion. Although shorter-term, tightly controlled feeding studies consistently identified benefits with increased protein consumption, longer-term studies produced limited and conflicting findings; nevertheless, a recent meta-analysis showed persistent benefits of a higher-protein weight-loss diet on body weight and fat mass. Dietary compliance appears to be the primary contributor to the discrepant findings because improvements in weight management were detected in those who adhered to the prescribed higher-protein regimen, whereas those who did not adhere to the diet had no marked improvements. Collectively, these data suggest that higher-protein diets that contain between 1.2 and 1.6 g protein $ kg 21 $ d 21 and potentially include meal-specific protein quantities of at least w25-30 g protein/meal provide improvements in appetite, body weight management, cardiometabolic risk factors, or all of these health outcomes; however, further strategies to increase dietary compliance with long-term dietary interventions are warranted. Am J Clin Nutr 2015;101(Suppl):1320S-9S.

LEIDY, HEATHER J., NADINE S. CARNELL, RICHARD D. MATTES, AND WAYNE W. CAMPBELL. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity. 2007; 15:421-429. Objective: To examine the effects of dietary protein and obesity classification on energy-restriction-induced changes in weight, body composition, appetite, mood, and cardiovascular and kidney health. Research Methods and Procedures: Forty-six women, ages 28 to 80, BMI 26 to 37 kg/m 2 , followed a 12-week 750-kcal/d energy-deficit diet containing higher protein (HP, 30% protein) or normal protein (NP, 18% protein) and were retrospectively subgrouped according to obesity classification [pre-obese (POB), BMI ϭ 26 to 29.9 kg/m 2 ; obese (OB), BMI ϭ 30 to 37 kg/m 2 ). Results: All subjects lost weight, fat mass, and lean body mass (LBM; p Ͻ 0.001). With comparable weight loss, LBM losses were less in HP vs. NP (Ϫ1.5 Ϯ 0.3 vs. Ϫ2.8 Ϯ 0.5 kg; p Ͻ 0.05) and POB vs. OB (Ϫ1.2 Ϯ 0.3 vs. Ϫ2.9 Ϯ 0.4 kg; p Ͻ 0.005). The main effects of protein and obesity on LBM changes were independent and additive; POB-HP lost less LBM vs. OB-NP (p Ͻ 0.05). The energy-restriction-induced decline in satiety was less pronounced in HP vs. NP (p Ͻ 0.005). Perceived pleasure increased with HP and decreased with NP (p Ͻ 0.05). Lipid-lipoprotein profile and blood pressure improved and kidney function minimally changed with energy restriction (p Ͻ 0.05), independently of protein intake. Discussion: Consuming a higher-protein diet and accomplishing weight loss before becoming obese help women preserve LBM. Use of a higher-protein diet also improves perceptions of satiety and pleasure during energy restriction.

Ghrelin is directly involved with short-term regulation of energy balance. Although circulating levels of ghrelin are elevated in anorexia nervosa and reduced in obesity, the role of ghrelin in regulating long-term energy balance in healthy women has not been investigated. We examined the effects of a 3-month energy deficit-imposing diet and exercise intervention on circulating ghrelin in normal-weight, healthy women. Body composition, resting metabolic rate, and serum ghrelin were measured at pre-, mid-, and postintervention in controls (n = 7), who performed no exercise, and exercising women who remained weight stable (n = 5) or lost weight (n = 10). Exercise training occurred five times per week, and subjects were fed a specific diet. Ghrelin significantly increased over time (770 +/- 296 to 1322 +/- 664 pmol/liter) in the weight-loss group compared with the controls and the weight-stable group (P < 0.05). Changes in ghrelin were negatively correlated with changes in body weight (r = -0.61; P < 0.05). Body fat, body weight, and resting metabolic rate significantly decreased in the weight-loss group before the increase in ghrelin. These findings suggest that ghrelin responds in a compensatory manner to changes in energy homeostasis in healthy young women, and that ghrelin exhibits particular sensitivity to changes in body weight.

Background: Breakfast skipping is a common dietary habit practiced among adolescents and is strongly associated with obesity.Objective: The objective was to examine whether a high-protein (HP) compared with a normal-protein (NP) breakfast leads to daily improvements in appetite, satiety, food motivation and reward, and evening snacking in overweight or obese breakfast-skipping girls.Design: A randomized crossover design was incorporated in which 20 girls [mean ± SEM age: 19 ± 1 y; body mass index (in kg/m2): 28.6 ± 0.7] consumed 350-kcal NP (13 g protein) cereal-based breakfasts, consumed 350-kcal HP egg- and beef-rich (35 g protein) breakfasts, or continued breakfast skipping (BS) for 6 d. On day 7, a 10-h testing day was completed that included appetite and satiety questionnaires, blood sampling, predinner food cue–stimulated functional magnetic resonance imaging brain scans, ad libitum dinner, and evening snacking.Results: The consumption of breakfast reduced daily hunger compared with BS with no differences between meals. Breakfast increased daily fullness compared with BS, with the HP breakfast eliciting greater increases than did the NP breakfast. HP, but not NP, reduced daily ghrelin and increased daily peptide YY concentrations compared with BS. Both meals reduced predinner amygdala, hippocampal, and midfrontal corticolimbic activation compared with BS. HP led to additional reductions in hippocampal and parahippocampal activation compared with NP. HP, but not NP, reduced evening snacking of high-fat foods compared with BS.Conclusions: Breakfast led to beneficial alterations in the appetitive, hormonal, and neural signals that control food intake regulation. Only the HP breakfast led to further alterations in these signals and reduced evening snacking compared with BS, although no differences in daily energy intake were observed. These data suggest that the addition of breakfast, particularly one rich in protein, might be a useful strategy to improve satiety, reduce food motivation and reward, and improve diet quality in overweight or obese teenage girls. This trial was registered at clinicaltrials.gov as NCT01192100.

Purpose of Review To highlight recent advances in nutrition and protein research that have the potential to improve health outcomes and status in aging adults. Recent Findings The beneficial effects of dietary protein on muscle health in older adults continue to be refined. Recent research has bolstered support for moderately increasing protein consumption beyond the current RDA by adopting a meal-based approach in lieu of a less specific daily recommendation. Results from muscle protein anabolism, appetite regulation and satiety research support that contention that meeting a protein threshold (approximately 30 g/meal) represents a promising strategy for middle-aged and older adults concerned with maintaining muscle mass while controlling body fat. Summary Optimizing dietary protein intake to improve health requires a detailed consideration of topics including muscle protein anabolism, appetite control and satiety. While each area of research continues to advance independently, recent collaborative and translational efforts have highlighted broad, translational consistencies related to the daily distribution and quantity of dietary protein.

Physical inactivity promotes the development of cardiovascular diseases. However, few data exist examining the vascular consequences of short-term reductions in daily physical activity. Thus we tested the hypothesis that popliteal and brachial artery flow-mediated dilation (FMD) would be reduced and concentrations of endothelial microparticles (EMPs) would be elevated following reduced daily physical activity. To examine this, popliteal and brachial artery FMD and plasma levels of EMPs suggestive of apoptotic and activated endothelial cells (CD31(+)/CD42b(-) and CD62E(+) EMPs, respectively) were measured at baseline and during days 1, 3, and 5 of reduced daily physical activity in 11 recreationally active men (25 ± 2 yr). Subjects were instructed to reduce daily physical activity by taking <5,000 steps/day and refraining from planned exercise. Popliteal artery FMD decreased with reduced activity (baseline: 4.7 ± 0.98%, reduced activity day 5: 1.72 ± 0.68%, P < 0.05), whereas brachial artery FMD was unchanged. In contrast, baseline (pre-FMD) popliteal artery diameter did not change, whereas brachial artery diameter decreased (baseline: 4.35 ± 0.12, reduced activity day 5: 4.12 ± 0.11 P < 0.05) following 5 days of reduced daily physical activity. CD31(+)/CD42b(-) EMPs were significantly elevated with reduced activity (baseline: 17.6 ± 9.4, reduced activity day 5: 104.1 ± 43.1 per μl plasma, P < 0.05), whereas CD62E(+) EMPs were unaltered. Collectively, our results provide evidence for the early and robust deleterious impact of reduced daily activity on vascular function and highlight the vulnerability of the vasculature to a sedentary lifestyle.

Background Breakfast skipping (BS) is closely associated with overeating (in the evening), weight gain and obesity. It is unclear whether the addition of breakfast, with emphasis on dietary protein, leads to better appetite and energy intake regulation in adolescents. Objective The purpose of the study was to examine the impact of addition of a normal-protein (PN) breakfast vs protein-rich (PR) breakfast on appetite and food intake in ‘breakfast-skipping’ adolescents. Subjects and Design A total of 13 adolescents (age 14.3 ± 0.3 years; body mass index percentile 79 ± 4 percentile; skipped breakfast 5 ± 1× per week) randomly completed 3 testing days that included a PN (18 ± 1 g protein), PR (48 ± 2 g protein) or BS. Breakfast was 24% of estimated daily energy needs. Appetite, satiety and hormonal responses were collected over 5 h followed by an ad libitum lunch and 24-h food intake assessments. Results Perceived appetite was not different following PN vs BS; PR led to greater reductions vs BS (P<0.01) and PN (P< 0.001). Fullness was greater following both breakfast meals vs BS (P<0.01) but was not different between meals. Ghrelin was not different among treatments. Greater PYY concentrations were observed following both breakfast meals vs BS (P<0.01) but was not different between meals. Lunch energy intake was not different following PN vs BS; PR led to fewer kcal consumed vs BS (P<0.01) and PN (P<0.005). Daily food intake was not different among treatments. Conclusions Breakfast led to increased satiety through increased fullness and PYY concentrations in ‘breakfast skipping’ adolescents. A breakfast rich in dietary protein provides additional benefits through reductions in appetite and energy intake. These findings suggest that the addition of a protein-rich breakfast might be an effective strategy to improve appetite control in young people.