The dietary protein allowance for older men to maintain lean body mass and muscle strength and to accrue optimal anabolic responses to promyogenic stimuli is poorly characterized. The OPTIMEN trial was designed to assess in older men with moderate physical dysfunction and insufficient habitual protein intake (
5.
Sarcopenic obesity in the elderly and strategies for weight management.
Li, Z, Heber, D
Nutrition reviews. 2012;(1):57-64
Abstract
Sarcopenia is a multifactorial age-related condition associated with a sedentary lifestyle and protein intakes during weight loss that are inadequate to maintain muscle mass. Sarcopenic obesity in the elderly is associated with a loss of independence and metabolic complications and represents a major public health challenge in individuals over the age of 65 years. It is likely that age-related losses of muscle mass and coincident increases in fat mass could be reduced through regular resistance exercise combined with adequate protein intake to maintain muscle mass. It has been established that increased protein intake will maintain muscle mass during calorie-restricted diets to a greater extent than usual protein intake. Other strategies, including the use of high-protein meal replacements or supplementation with specific ergogenic or branched-chain amino acids, may be beneficial.
6.
High-carbohydrate/low-protein-induced hyperinsulinemia does not improve protein balance in children after cardiac surgery.
Geukers, VG, Li, Z, Ackermans, MT, Bos, AP, Jinfeng, L, Sauerwein, HP
Nutrition (Burbank, Los Angeles County, Calif.). 2012;(6):644-50
Abstract
OBJECTIVE In pediatric cardiac surgery, fluid-restricted low-protein (LoProt) diets account for cumulative protein deficits with increased morbidity. In this setting, we aimed to inhibit proteolysis by a high-carbohydrate (HiCarb)-intake-induced hyperinsulinemia and improve protein balance. METHODS The effect of a HiCarb/LoProt (glucose 10 mg · kg(-1) · min(-1)/protein 0.7 g · kg(-1) · d(-1)) versus a normal-carbohydrate (NormCarb)/LoProt (glucose 7.5 mg · kg(-1) · min(-1)/protein 0.3 g · kg(-1) · d(-1)) enteral diet on whole-body protein breakdown and balance was compared in a prospective, randomized, single-blinded trial in 24 children after cardiac surgery. On the second postoperative day, plasma insulin and amino acid concentrations, protein breakdown (endogenous rate of appearance of valine), protein synthesis (non-oxidative disposal of valine), protein balance, and the rate of appearance of urea were measured by using an isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea. RESULTS The HiCarb/LoProt diet led to a serum insulin concentration that was three times higher than the NormCarb/LoProt diet (596 pmol/L, 80-1833, and 198 pmol/L, 76-1292, respectively, P = 0.02), without differences in plasma glucose concentrations. There were no differences in plasma amino acid concentrations, non-oxidative disposal of valine, and endogenous rate of appearance of valine between the groups, with a negative valine balance in the two groups (-0.65 μmol · kg(-1) · min(-1), -1.91 to 0.01, and -0.58 μmol · kg(-1) · min(-1), -2.32 to -0.07, respectively, P = 0.71). The serum cortisol concentration in the HiCarb/LoProt group was lower compared with the NormCarb/LoProt group (204 nmol/L, 50-544, and 532 nmol/L, 108-930, respectively, P = 0.02). CONCLUSION In children with fluid restriction after cardiac surgery, a HiCarb/LoProt diet compared with a NormCarb/LoProt diet stimulates insulin secretion but does not inhibit proteolysis further and therefore cannot be advocated for this purpose.
7.
Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial.
Li, Z, Treyzon, L, Chen, S, Yan, E, Thames, G, Carpenter, CL
Nutrition journal. 2010;:72
Abstract
BACKGROUND There is concern that recommending protein-enriched meal replacements as part of a weight management program could lead to changes in biomarkers of liver or renal function and reductions in bone density. This study was designed as a placebo-controlled clinical trial utilizing two isocaloric meal plans utilizing either a high protein-enriched (HP) or a standard protein (SP) meal replacement in an outpatient weight loss program. SUBJECTS/METHODS 100 obese men and women over 30 years of age with a body mass index (BMI) between 27 to 40 kg/m2 were randomized to one of two isocaloric weight loss meal plans 1). HP group: providing 2.2 g protein/kg of lean body mass (LBM)/day or 2). SP group: providing 1.1 g protein/kg LBM/day. Meal replacement (MR) was used twice daily (one meal, one snack) for 3 months and then once a day for 9 months. Body weight, lipid profiles, liver function, renal function and bone density were measured at baseline and 12 months. RESULTS Seventy subjects completed the study. Both groups lost weight (HP -4.29 ± 5.90 kg vs. SP -4.66 ± 6.91 kg, p < 0.01) and there was no difference in weight loss observed between the groups at one year. There was no significant change noted in liver function [AST (HP -2.07 ± 10.32 U/L, p = 0.28; SP 0.27 ± 6.67 U/L, p = 0.820), ALT (HP -1.03 ± 10.08 U/L, p = 0.34; SP -2.6 ± 12.51 U/L, p = 0.24), bilirubin (HP 0.007 ± 0.33, U/L, p = 0.91; SP 0.07 ± 0.24 U/L, p = 0.120), alkaline phosphatase (HP 2.00 ± 9.07 U/L, p = 0.240; SP -2.12 ± 11.01 U/L, p = 0.280)], renal function [serum creatinine (HP 0.31 ± 1.89 mg/dL, p = 0.380; SP -0.05 ± 0.15 mg/dL, p = 0.060), urea nitrogen (HP 1.33 ± 4.68 mg/dL, p = 0.130; SP -0.24 ± 3.03 mg/dL, p = 0.650), 24 hour urine creatinine clearance (HP -0.02 ± 0.16 mL/min, p = 0.480; SP 1.18 ± 7.53 mL/min, p = 0.400), and calcium excretion (HP -0.41 ± 9.48 mg/24 hours, p = 0.830; SP -0.007 ± 6.76 mg/24 hours, p = 0.990)] or in bone mineral density by DEXA (HP 0.04 ± 0.19 g/cm2, p = 0.210; SP -0.03 ± 0.17 g/cm2, p = 0.320) in either group over one year. CONCLUSIONS These studies demonstrate that protein-enriched meals replacements as compared to standard meal replacements recommended for weight management do not have adverse effects on routine measures of liver function, renal function or bone density at one year.
8.
Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
Evangelista, LS, Heber, D, Li, Z, Bowerman, S, Hamilton, MA, Fonarow, GC
The Journal of cardiovascular nursing. 2009;(3):207-15
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Abstract
BACKGROUND The effectiveness of high-protein (HP) diets in reducing body weight and adiposity and potentially improving clinical outcomes in heart failure (HF) is not known. OBJECTIVE This feasibility study was conducted to evaluate the impact of 3 dietary interventions on body weight and adiposity, functional status, lipid profiles, glycemic control, and quality of life (QOL) in overweight and obese patients with HF and type 2 diabetes mellitus. DESIGN Fourteen patients with HF with a body mass index greater than 27 kg/m2 were randomized to an HP diet, a standard protein diet, or a conventional diet. Data were obtained at baseline and 12 weeks. RESULTS There were no significant differences in age (59 +/- 10 years), sex (78% male), New York Heart Association class (43% class II, 57% class III), and HF etiology or left ventricular ejection fraction (26 +/- 7) between the groups at baseline. Patients on the HP diet demonstrated significantly greater reductions in weight (P = .005), percent body fat (P = .036), total cholesterol (P = .016), triglyceride concentrations (P = .034), and low-density lipoprotein cholesterol (P = .041) and greater improvements in functional status (6-minute walk [P = .010] and VO2 peak [P = .003]), high-density lipoprotein cholesterol (P = .006), and physical QOL scores (P = .022) compared with those on standard protein and conventional diets. CONCLUSION A 12-week HP diet resulted in moderate weight loss and reduced adiposity in a small sample of overweight and obese patients with HF that were associated with improvements in functional status, lipid profiles, glycemic control, and QOL. However, these preliminary findings must be confirmed in studies with more participants and long-term follow-up.
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A controlled trial of protein enrichment of meal replacements for weight reduction with retention of lean body mass.
Treyzon, L, Chen, S, Hong, K, Yan, E, Carpenter, CL, Thames, G, Bowerman, S, Wang, HJ, Elashoff, R, Li, Z
Nutrition journal. 2008;:23
Abstract
BACKGROUND While high protein diets have been shown to improve satiety and retention of lean body mass (LBM), this study was designed to determine effects of a protein-enriched meal replacement (MR) on weight loss and LBM retention by comparison to an isocaloric carbohydrate-enriched MR within customized diet plans utilizing MR to achieve high protein or standard protein intakes. METHODS Single blind, placebo-controlled, randomized outpatient weight loss trial in 100 obese men and women comparing two isocaloric meal plans utilizing a standard MR to which was added supplementary protein or carbohydrate powder. MR was used twice daily (one meal, one snack). One additional meal was included in the meal plan designed to achieve individualized protein intakes of either 1) 2.2 g protein/kg of LBM per day [high protein diet (HP)] or 2) 1.1 g protein/kg LBM/day standard protein diet (SP). LBM was determined using bioelectrical impedance analysis (BIA). Body weight, body composition, and lipid profiles were measured at baseline and 12 weeks. RESULTS Eighty-five subjects completed the study. Both HP and SP MR were well tolerated, with no adverse effects. There were no differences in weight loss at 12 weeks (-4.19 +/- 0.5 kg for HP group and -3.72 +/- 0.7 kg for SP group, p > 0.1). Subjects in the HP group lost significantly more fat weight than the SP group (HP = -1.65 +/- 0.63 kg; SP = -0.64 +/- 0.79 kg, P = 0.05) as estimated by BIA. There were no significant differences in lipids nor fasting blood glucose between groups, but within the HP group a significant decrease in cholesterol and LDL cholesterol was noted at 12 weeks. This was not seen in the SP group. CONCLUSION Higher protein MR within a higher protein diet resulted in similar overall weight loss as the standard protein MR plan over 12 weeks. However, there was significantly more fat loss in the HP group but no significant difference in lean body mass. In this trial, subject compliance with both the standard and protein-enriched MR strategy for weight loss may have obscured any effect of increased protein on weight loss demonstrated in prior weight loss studies using whole food diets.