Normal vs. high-protein weight loss diets in men: effects on body composition and indices of metabolic syndrome

Enhanced protein intake on maintaining muscle mass, strength, and physical function in adults with overweight/obesity: A systematic review and meta-analysis

BACKGROUND & AIMS

Weight loss in individuals with obesity and overweight leads to metabolic and health benefits but also poses the risk of muscle mass reduction. This systematic review and meta-analysis of randomized controlled trials aims to determine the initial protein amount necessary for achieving weight loss while maintaining muscle mass, strength, and physical function in adults with overweight and obesity.

METHODS

Relevant literature databases, including Medical Literature Analysis and Retrieval System Online (Medline), Excerpta Medica (Embase), the Cumulative Index to Nursing and Allied Health Literature (CINHAL), and Web of Science, were electronically searched up to 15 March 2023. We examined the effect of additional protein intake on muscle mass, strength, and physical function in adults with overweight or obesity targeting weight loss. The risk of bias was assessed using the Cochrane RoB 2.0 tool. Results were synthesized using standardized mean differences (SMD) and 95% confidence intervals (CI) via a random-effects model.

RESULTS

Forty-seven studies (n = 3218) were included. In the muscle mass analysis, twenty-eight trials with 1989 participants were encompassed. Results indicated that increased protein intake significantly prevents muscle mass decline in adults with overweight or obesity aiming for weight loss (SMD 0.75; 95% CI 0.41 to 1.10; p < 0.001). Enhanced protein intake did not significantly prevent decreases in muscle strength and physical function. An intake exceeding 1.3 g/kg/day is anticipated to increase muscle mass, while an intake below 1.0 g/kg/day is associated with a higher risk of muscle mass decline. The risk of bias in studies regarding muscle mass ranged from low to high.

CONCLUSIONS

Adults with overweight or obesity and aim for weight loss can more effectively retain muscle mass through higher protein intake, as opposed to no protein intake enhancement.

A Higher-Protein, Energy Restriction Diet Containing 4 Servings of Fresh, Lean Beef per Day Does Not Negatively Influence Circulating miRNAs Associated with Cardiometabolic Disease Risk in Women with Overweight

This study examined the acute effects of 7-d energy restriction normal-protein (NP; ∼15% of daily intake as protein) compared with higher-protein (HP; ∼38% of daily intake as protein) diets varying in quantities of fresh, lean beef on circulating miRNA expression associated with cardiometabolic disease in 16 women with overweight (mean ± SD; age: 35 ± 8.7 y; body mass index: 28.5 ± 1.9 kg/m2). Fasting blood samples were collected at the end of each diet for miRNA expression, glucose, insulin, adiponectin, C-reactive protein (CRP), and IL-6. Of the 12 surveyed, 10 miRNAs (miR-320a-3p, miR-146a-5p, miR-150-5p, miR-423-5p, miR-122-5p, miR-223-3p, miR-199a-5p, miR-214-3p, miR-24-3p, and miR-126-3p) were detected. Several miRNAs were associated with fasting CRP (i.e., miR-150-5p, miR-24-3p, miR-423-5p; all P < 0.05). miR-423-5p was also associated with fasting glucose, IL-6, and homeostasis model assessment 2 %β cell function (all, P < 0.05). No differences in miRNA expression were identified between diets. These data suggest that fresh, lean beef in a short-term HP, energy restriction diet does not negatively influence circulating miRNAs associated with cardiometabolic disease in women. This trial was registered at clinicaltrials.gov as NCT02614729.

Effects of high-protein diets on the cardiometabolic factors and reproductive hormones of women with polycystic ovary syndrome: a systematic review and meta-analysis

The optimal dietary regimen for polycystic ovary syndrome (PCOS) has not been identified. High-protein diets (HPDs) are effective for weight control in individuals with metabolic abnormalities, but no systematic meta-analyses have yet summarised the effects of HPDs on PCOS. Seven electronic databases were searched from inception to 30 April 2023, and studies comparing the effects of HPDs and other diets on the anthropometrics, metabolic factors, and hormonal profiles for PCOS were identified. Data were pooled using random-effects models and expressed as weighted mean differences and 95% confidence intervals. The risk of bias was assessed by Cochrane Collaboration tool. Eight trials involving 300 women with PCOS were included. Compared with isocaloric balanced diets (BDs), HPDs significantly reduced fasting insulin (-2.69 μIU/mL, 95% CI [-3.81, -1.57], P < 0.0001, I2 = 46%) and homoeostatic model assessment for insulin resistance (HOMA-IR-0.41, 95% CI [-0.80, -0.02], P = 0.04, I2 = 94%) in women with PCOS. However, HPDs and BDs had comparable effects on weight loss, abdominal adiposity, lipid profiles, and reproductive hormones (all P ≥ 0.05). HPDs may benefit women with PCOS in terms of improving insulin resistance, supporting for their use as one of the dietary management options for PCOS, however further RCTs in larger and broader settings are required to confirm these observations and investigate the mechanism behind it.

The comparison of total energy and protein intake relative to estimated requirements in chronic spinal cord injury

In chronic spinal cord injury (SCI), individuals experience dietary inadequacies complicated by an understudied research area. Our objectives were to assess (1) the agreement between methods of estimating energy requirement (EER) and estimated energy intake (EEI) and (2) whether dietary protein intake met SCI-specific protein guidelines. Persons with chronic SCI (n = 43) completed 3-day food records to assess EEI and dietary protein intake. EER was determined with the Long and Institute of Medicine (IOM) methods and the SCI-specific Farkas method. Protein requirements were calculated as 0·8-1·0 g/kg of body weight (BW)/d. Reporting accuracy and bias were calculated and correlated to body composition. Compared with IOM and Long methods (P < 0·05), the SCI-specific method did not overestimate the EEI (P = 0·200). Reporting accuracy and bias were best for SCI-specific (98·9 %, -1·12 %) compared with Long (94·8 %, -5·24 %) and IOM (64·1 %, -35·4 %) methods. BW (r = -0·403), BMI (r = -0·323) and total fat mass (r = -0·346) correlated with the IOM reporting bias (all, P < 0·05). BW correlated with the SCI-specific and Long reporting bias (r = -0·313, P = 0·041). Seven (16 %) participants met BW-specific protein guidelines. The regression of dietary protein intake on BW demonstrated no association between the variables (β = 0·067, P = 0·730). In contrast, for every 1 kg increase in BW, the delta between total and required protein intake decreased by 0·833 g (P = 0·0001). The SCI-specific method for EER had the best agreement with the EEI. Protein intake decreased with increasing BW, contrary to protein requirements for chronic SCI.

Evidence-Based Strategies to Enhance Weight Management Programs for Adult Military Beneficiaries: A Narrative Review

INTRODUCTION

Overweight and obesity trends are on the rise among both civilian and military beneficiaries. The purpose of this narrative review was to evaluate nutrition, behavioral, lifestyle, pharmacotherapy, and alternative approaches to weight management (WM) among adults with a focus toward identifying gaps and evidence-based strategies that could support or enhance current and future WM programming among military adult beneficiaries.

MATERIALS AND METHODS

A trained research team identified publications (January 2013-January 2020) for abstract review using key search terms and inclusion criteria. Two independent researchers conducted both the abstract review and full-paper bias scoring using selected Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. All eligible studies were assessed for bias and categorized based on key themes. The study was registered in PROSPERO, the international prospective register of systematic reviews.

RESULTS

The research team identified 741 articles, with 278 meeting final inclusion criteria. The mean bias score was 7.5 ± 3.9 (score of 0-13; higher indicating fewer bias factors), with 64% scoring ≥9. Factors contributing to low bias included intervention compliance, dropout rate, and inability to blind participants. The most common published weight-loss interventions included a combination of therapies (59%), diet/supplement (17%), other approaches (12%), behavior change (7%), and exercise (6%). Themes identified to improve WM outcomes included leveraging technology, increasing intervention interactions, community support, emphasis on early weight loss, pharmacotherapy risk-benefit, enhanced behavioral component, resistance exercise, mindfulness, and benefits of quality-of-life measures.

CONCLUSIONS

Reviewers identified several validated tools and techniques to augment and update existing WM programming to improve health and weight outcomes. The review affirmed use of individualized dietary patterns and not a "one-size-fits-all approach" as well as incorporating more comprehensive and team-approached treatments to make the best use of tools and strategies to enhance outcomes.

Concept of an Intervention for Sustainable Weight Loss in Postmenopausal Women with Overweight-Secondary Analysis of a Randomized Dietary Intervention Study

INTRODUCTION

The approach of an individual diet has great potential for sustainable weight reduction. Social support, participation and empowerment are also key factors for high motivation and compliance. So, the impact of an individual diet in combination with group sessions on weight loss in postmenopausal women with overweight was investigated.

METHODS

In this reanalysis of a controlled intervention study, postmenopausal women (n = 54; BMI 30.9 ± 3.4 kg/m²; 59 ± 7 years) were recruited receiving an energy restricted diet for 12 weeks, followed by a six-month follow-up phase. The women received 51 individual meal plans based on their habits and were trained in four group sessions.

RESULTS

Forty-six women completed the intervention phase, and 29 completed the follow-up. Average weight loss was -5.8 ± 3.0 kg (p < 0.001) after 12 weeks and was still significant at follow-up (-4.9 ± 5.4 kg, p < 0.001). Also, decreases in fat-free mass (-1.1 ± 1.2 kg, p < 0.001) and resting energy expenditure (-1096 ± 439 kJ/24 h, p < 0.001) were observed.

CONCLUSIONS

The individual nutrition approach with a focus on nutritype in combination with group sessions was effective for long-lasting weight loss in postmenopausal women. An important factor is close individual and group support.

Effects of protein intake from an energy-restricted diet on the skeletal muscle composition of overweight and obese rats

Excess weight and obesity are often associated with ectopic adipose tissue accumulation in skeletal muscles. Intermuscular adipose tissue (IMAT) impairs muscle quality and reduces insulin-stimulated skeletal muscle glucose uptake. Although energy restriction and high protein intake can decrease IMAT, the effects and mechanisms of protein intake from an energy-restricted diet on protein and fat masses in skeletal muscle have received little attention. After establishing a diet-induced overweight and obese Sprague-Dawley rat model (half male and half female), rats were divided into five groups: normal control (NC; normal weight, general maintenance diet), model control (MC; overweight and obesity, high-fat diet), energy-restricted low protein (LP; overweight and obesity, 60% energy intake of NC, general maintenance diet), energy-restricted normal protein (NP; overweight and obesity, 60% energy intake of NC, high-protein diet 1), and energy-restricted high protein (HP; overweight and obesity, 60% energy intake of NC, high-protein diet 2). After 8 weeks, plasma and skeletal muscle (quadriceps femoris and gastrocnemius) samples were collected. Plasma levels of glucose, triglycerides, and hormones were analyzed, while contents of protein, fat, and factors associated with their synthesis and degradation were evaluated in skeletal muscles. Plasma concentrations of hormones contrasted protein and fat contents in skeletal muscles. Fat weights and contents of quadriceps femoris and gastrocnemius muscles in the NP group were significantly lower compared with LP and HP groups (P < 0.05). Moreover, concentrations of factors associated with the degradation of muscle fat were significantly higher in the NP group compared with LP and HP groups (P < 0.05). During energy restriction, protein intake equal to that of a normal protein diet increased lipolysis of quadriceps femoris and gastrocnemius muscles in rats of both sexes.

Effects of Thai native chicken breast meat consumption on serum uric acid level, biochemical parameters, and antioxidant activities in rats

This study aimed to evaluate the effect of a high protein diet comprising breast meat from commercial broiler (BR), Thai native (PD), and commercial broiler × Thai native crossbred (KKU-ONE) chicken on serum uric acid, biochemical parameters, and antioxidant activities in rats. Male Sprague–Dawley rats were divided into four groups. The control group received a standard chow diet, and the other three groups were fed a high protein diet (70% standard diet + 30% BR, PD, or KKU-ONE chicken breast) for five weeks. The PD- and KKU-ONE-fed rats had lower plasma total cholesterol and triglyceride levels than the control rats. A decrease in HDL-c was also observed in rats fed a diet containing BR. Liver weight, liver enzyme, plasma ALP, xanthine oxidase activity, serum uric acid, creatinine, superoxide production, and plasma malondialdehyde levels increased in BR-fed rats. The findings of this study might provide evidence to support the use of Thai native and Thai native crossbred chicken breast meat as functional foods.

Interventions for Body Composition and Upper and Lower Extremity Muscle Strength in Older Adults in Rural Taiwan: A Horizontal Case Study

The purpose of this study was to understand the effects of a physical activity program and high-protein supplementation on body composition and upper and lower extremity muscle strength in male older adults in rural areas. In this study, 60 healthy male older adults (mean age 77.5 ± 4.6 years) from rural areas were recruited and randomly assigned to experimental group A (intervention of the physical activity program and high-protein supplementation), experimental group B (daily routine, with only intervention of high-protein supplementation), or control group C (daily routine). Experimental group A (EGa) carried out a physical activity plan three times a week, with an exercise intensity and calorie consumption of 250 kcal (5METs × ⅔hr × 75) for 3 months and drank a high-protein supplement (1.3 g/kg BW/day) after each exercise; experimental group B (EGb) followed only the intervention of high-protein supplementation. All the participants underwent pre- and post-tests for body composition, waist–hip circumference (WC, HC), handgrip strength (HS), 30 s dominant arm curl, 30 s sit to stand, and 2 min step tests. The results of the study showed that EGa significantly decreased body mass index (BMI), body fat mass (BFM), body fat percentage (BFP), WC, HC, and waist-to-hip ratio (WHR) and increased basal metabolic rate and muscle mass. Although both EGa and EGb used high-protein supplementation, EGa’s added three-month intervention of a physical activity program made it easier for that group to increase muscle mass and muscle strength. The WHR decreased from 1.015 to 0.931, representing a decrease of 8.28%, and an obvious weight loss effect was achieved. Thus, we concluded that the best way to maintain muscle strength in older adults is through physical activity with resistance and protein supplementation, which can reduce muscle loss in older adults.

Circulating oestradiol determines liver lipid deposition in rats fed standard diets partially unbalanced with higher lipid or protein proportions

The ingestion of excess lipids often produces the accumulation of liver fat. The modulation of diet energy partition affects this process and other metabolic responses, and oestrogens and androgens are implied in this process. Ten-week-old male and female rats were fed with either standard rat chow (SD), SD enriched with coconut oil (high-fat diet, HF), SD enriched with protein (high-protein diet, HP) or a ‘cafeteria’ diet (CAF) for 1 month. HF and CAF diets provided the same lipid-derived percentage of energy (40 %), HP diet protein energy derived was twice (40 %) that of the SD. Animals were killed under anaesthesia and samples of blood and liver were obtained. Hepatic lipid content showed sex-related differences: TAG accumulation tended to increase in HF and CAF fed males. Cholesterol content was higher only in the CAF males. Plasma oestradiol in HF and HP males was higher than in CAF. Circulating cholesterol was inversely correlated with plasma oestradiol. These changes agreed with the differences in the expression of some enzymes related to lipid and energy metabolism, such as fatty acid synthetase or phosphoglycolate phosphatase. Oestrogen protective effects extend to males with ‘normal’ diets, that is, not unbalanced by either lipid or protein, but this protection was not enough against the CAF diet. Oestradiol seems to actively modulate the liver core of 2C-3C partition of energy substrates, regulating cholesterol deposition and lactate production.

Are Dietary Proteins the Key to Successful Body Weight Management? A Systematic Review and Meta-Analysis of Studies Assessing Body Weight Outcomes after Interventions with Increased Dietary Protein

The primary aim was to systematically review the current evidence investigating if dietary interventions rich in protein lead to improved body weight management in adults with excessive body weight. The secondary aim was to investigate potential modifying effects of phenotyping. A systematic literature search in PubMed, Web of Science, and Cochrane Library identified 375 randomized controlled trials with 43 unique trials meeting the inclusion criteria. The Cochrane collaboration tool was used for a thorough risk of bias assessment. Based on 37 studies evaluating effects of dietary protein on body weight, the participants with increased protein intake (ranging from 18–59 energy percentage [E%]) were found to reduce body weight by 1.6 (1.2; 2.0) kg (mean [95% confidence interval]) compared to controls (isocaloric interventions with energy reduction introduced in certain studies). Individuals with prediabetes were found to benefit more from a diet high in protein compared to individuals with normoglycemia, as did individuals without the obesity risk allele (AA genotype) compared to individuals with the obesity risk alleles (AG and GG genotypes). Thus, diets rich in protein would seem to have a moderate beneficial effect on body weight management.

Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Higher protein (HP) diets may lead to lower cardiometabolic risk, compared to lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP versus LP diets on cardiometabolic risk factors in adults, using the totality of the current evidence from randomised controlled trials (RCTs).

METHODS

Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.

RESULTS

Fifty-seven articles reporting on 54 RCTs were included, involving 4344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m²), with a mean study duration of 18 weeks (range: 4 to 156 weeks). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.

CONCLUSIONS

Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.

Causal relationship between dietary macronutrient composition and anthropometric measures: A bidirectional two-sample Mendelian randomization analysis

BACKGROUND

The question whether the proportion of energy provided by fat and carbohydrates in the diet is associated with body mass index (BMI) and waist circumference (WC) is an important public health issue, but determining causality is difficult in epidemiological studies.

OBJECTIVES

Using a two-sample bidirectional Mendelian randomization (MR) in both a univariable and multivariable setting, we aimed to determine whether the relative proportion of different macronutrients in the diet (in % of total energy intake (E%)) is causally related to BMI and WC and vice versa.

METHODS

All analyses were based on genome-wide association studies including 268,922 Europeans with dietary data (SSGAC Consortium) and at least 232,101 with anthropometric measures (GIANT Consortium). An inverse-variance weighted approach using modified second-order weights within the radial regression framework was performed. Radial MR-Egger, weighted median and mode, Robust Adjusted Profile Score (RAPS), and Pleiotropy RESidual Sum and Outlier (PRESSO) methods were used in sensitivity analyses to verify MR assumptions. Additionally, multivariable MR was conducted to account for inter correlation between macronutrient intakes. All estimates represent the standard deviation (SD) change in each outcome per one SD change in the respective exposure.

RESULTS

We found that genetically predicted relative carbohydrate intake (E%) reduced BMI (β = -0.529; 95% CI: -0.745, -0.312; P-value = 2⋅10^-6) and WC (β = -0.459; 95% CI: -0.656, -0.262; P-value = 5⋅10^-6). Both effects were also supported by the multivariable approach: β = -0.441 (95% CI: -0.772, -0.109; P-value = 0.009) for BMI and β = -0.410 (95% CI: -0.667, -0.154; P-value = 0.002) for WC. Genetically predicted dietary intake of fat (E%) was weaker and positively related to both anthropometric measures. We obtained evidence that a higher BMI and WC increased the relative dietary intake of fat and protein (E%). For example, each SD higher BMI increased protein intake (E%) by 0.114 SD (95% CI: 0.081, 0.147; P-value = 9⋅10^-12) and each SD higher WC increased protein intake (E%) by 0.078 SD (95% CI: 0.035, 0.121; P-value = 4⋅10^-4). Sensitivity analyses confirmed these findings revealing consistent effect estimates.

CONCLUSIONS

Using genetic information to improve causal inference we found evidence, that a low relative carbohydrate proportion (E%) and a high proportion of fat (E%) in the diet is causally related to a higher BMI and a higher WC. Further research considering carbohydrate, fat, and protein quality and possible consequences on micronutrient intake is needed to define the implications for dietary intake recommendations.

The impact of type of dietary protein, animal versus vegetable, in modifying cardiometabolic risk factors: A position paper from the International Lipid Expert Panel (ILEP)

Proteins play a crucial role in metabolism, in maintaining fluid and acid-base balance and antibody synthesis. Dietary proteins are important nutrients and are classified into: 1) animal proteins (meat, fish, poultry, eggs and dairy), and, 2) plant proteins (legumes, nuts and soy). Dietary modification is one of the most important lifestyle changes that has been shown to significantly decrease the risk of cardiovascular (CV) disease (CVD) by attenuating related risk factors. The CVD burden is reduced by optimum diet through replacement of unprocessed meat with low saturated fat, animal proteins and plant proteins. In view of the available evidence, it has become acceptable to emphasize the role of optimum nutrition to maintain arterial and CV health. Such healthy diets are thought to increase satiety, facilitate weight loss, and improve CV risk. Different studies have compared the benefits of omnivorous and vegetarian diets. Animal protein related risk has been suggested to be greater with red or processed meat over and above poultry, fish and nuts, which carry a lower risk for CVD. In contrast, others have shown no association of red meat intake with CVD. The aim of this expert opinion recommendation was to elucidate the different impact of animal vs vegetable protein on modifying cardiometabolic risk factors. Many observational and interventional studies confirmed that increasing protein intake, especially plant-based proteins and certain animal-based proteins (poultry, fish, unprocessed red meat low in saturated fats and low-fat dairy products) have a positive effect in modifying cardiometabolic risk factors. Red meat intake correlates with increased CVD risk, mainly because of its non-protein ingredients (saturated fats). However, the way red meat is cooked and preserved matters. Thus, it is recommended to substitute red meat with poultry or fish in order to lower CVD risk. Specific amino acids have favourable results in modifying major risk factors for CVD, such as hypertension. Apart from meat, other animal-source proteins, like those found in dairy products (especially whey protein) are inversely correlated to hypertension, obesity and insulin resistance.

Impact of Protein Intake during Weight Loss on Preservation of Fat-Free Mass, Resting Energy Expenditure, and Physical Function in Overweight Postmenopausal Women: A Randomized Controlled Trial

INTRODUCTION

Weight loss in old age increases the risk of sarcopenia caused by the age-related reduction of fat-free mass (FFM). Due to the strong correlation between FFM and resting energy expenditure (REE), the maintenance of this must also be considered. Besides, the physical function (PF) must be maintained.

OBJECTIVE

The impact of protein intake on changes in FFM, REE, and PF during weight loss in overweight postmenopausal women was investigated.

METHODS

Fifty-four postmenopausal women (BMI 30.9 ± 3.4; age 59 ± 7 years) were randomized into 2 groups receiving energy-restricted diets with either 0.8 g (normal protein; NP) or 1.5 g protein/kg body weight (high protein; HP) for 12 weeks, followed by a 6-month follow-up phase with an ad libitum food intake. FFM, REE, and PF (strength, endurance, and balance) were measured at baseline, after weight loss, and after follow-up.

RESULTS

Forty-six women completed the weight loss intervention and 29 were followed up. The weight loss was -4.6 ± 3.6 kg (HP) and -5.2 ± 3.4 kg (NP; both p < 0.001) and the weight regain during follow-up was 1.3 ± 2.8 kg (HP; p = 0.03) and 0.4 ± 2.5 kg (NP; p = 0.39), with no differences between groups. Similar decreases in FFM (-0.9 ± 1.1 [HP] vs. -1.0 ± 1.3 kg [NP]) and REE (-862 ± 569 [HP] vs. -1,000 ± 561 kJ [NP]; both p < 0.001) were observed in both groups. During follow-up, no changes in FFM were detected in either group, whereas in the NP group the REE increased again (+138 ± 296; p = 0.02). The main determinants of FFM loss were the energy deficit and the speed of weight loss. In the NP group, the Short Physical Performance Battery score improved with weight loss (+0.6 ± 0.8; p < 0.001) and handgrip strength decreased (-1.7 ± 3.4 kg; p < 0.001), whereas no changes were observed in the HP group.

CONCLUSIONS

An HP weight-loss diet without exercise had no impact on preservation of FFM and REE but may help to maintain muscle strength in postmenopausal women.

Bariatric surgery affects obesity-related protein requirements

CONTEXT

Following bariatric surgery, protein deficiency intakes are reported in morbidly obese patients, whereas post-bariatric protein requirements are not specifically defined with validated method in this population.

OBJECTIVE

To assess average protein requirement (APR) in obese subjects, before, 3 months and 12 months after bariatric surgery using the validated method of nitrogen balance.

DESIGN AND SETTING

Prospective longitudinal study conducted in 21 morbidly obese patients (BMI 43.9 ± 1.4 kg/m²) before (M0), 3 months (M3) and 12 months (M12) after sleeve gastrectomy or Roux-en-Y gastric by-pass. An additional larger cross-sectional study was performed to validate APR before surgery in non-operated matched obese patients (n = 106). APR was evaluated at M0, M3, M12 by measuring 3 days dietary intakes together with losses of nitrogen in urine and stools.

MAIN OUTCOME MEASURE

APR was defined as the mean value of protein intake required to achieve balance nitrogen equilibrium.

RESULTS

Before surgery, APR in morbidly obese patients was 0.76 [95%CI, 0.66-0.92] g/kg Body Weight (BW)/d in the experimental group, and 0.74 [0.70-0.80] g/kg BW/d in the validation group. APR was 0.62 [0.51-0.75] g/kg/d at M3 and 0.87 [0.75-0.98] g/kg/d at M12, with no difference between surgical procedures. Spontaneous protein intakes were respectively 0.80 ± 0.05, 0.43 ± 0.03 and 0.71 ± 0.04 g/kg BW/d respectively at M0, M3 and M12.

CONCLUSION

This study demonstrates a temporal change in protein requirement after bariatric surgery whatever the type of surgery. Spontaneous protein intakes following bariatric surgery does not cover protein requirements for most patients, suggesting that specific dietary protein recommandations have to be adapted in obese patients with bariatric surgery.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01249326.

Does high dietary protein intake contribute to the increased risk of developing prediabetes and type 2 diabetes?

Insulin resistance is a complex metabolic disorder implicated in the development of many chronic diseases. While it is generally accepted that body mass loss should be the primary approach for the management of insulin resistance-related disorders in overweight and obese individuals, there is no consensus among researchers regarding optimal protein intake during dietary restriction. Recently, it has been suggested that increased plasma branched-chain amino acids concentrations are associated with the development of insulin resistance and type 2 diabetes. The exact mechanism by which excessive amino acid availability may contribute to insulin resistance has not been fully investigated. However, it has been hypothesised that mammalian target of rapamycin (mTOR) complex 1 hyperactivation in the presence of amino acid overload contributes to reduced insulin-stimulated glucose uptake because of insulin receptor substrate (IRS) degradation and reduced Akt-AS160 activity. In addition, the long-term effects of high-protein diets on insulin sensitivity during both weight-stable and weight-loss conditions require more research. This review focusses on the effects of high-protein diets on insulin sensitivity and discusses the potential mechanisms by which dietary amino acids can affect insulin signalling. Novelty: Excess amino acids may over-activate mTOR, resulting in desensitisation of IRS-1 and reduced insulin-mediated glucose uptake.

The effect of 12 weeks of euenergetic high-protein diet in regulating appetite and body composition of women with normal-weight obesity: a randomised controlled trial

Normal-weight obesity (NWO) syndrome is associated with metabolic diseases. The present study aimed to investigate the effects of 12 weeks of a high-protein (HP) v. a standard protein (SP) diet on appetite, anthropometry and body composition in NWO women. In this clinical trial, fifty NWO women were randomly allocated to HP (n 25) or SP (n 25) diet groups. Women in the HP and SP groups consumed 25 and 15 % of their total energy intake from protein for 12 weeks. Weight, fat mass (FM), lean body mass (LBM), waist circumference (WC) and appetite were evaluated at baseline and following their 3-month intervention. After 12 weeks, the LBM was higher in HP compared with no significant changes in the SP group (mean between-group difference = 1·5 kg; 95 % CI 3·1, 0·01; effect size (d) = 0·4). Furthermore, the HP group had lower FM (mean between-group difference -1·1 kg; 95 % CI 1, -3·3; d = -0·2), body fat percentage (BFP) (mean between-group difference -2 %; 95 % CI 0·7, -5·2; d = -0·3) and WC (mean between-group difference -1·4 cm; 95 % CI 0·6, -3·6; d = -0·2) at the end of the study in comparison with the SP group. In both groups, weight and appetite were unchanged over time without significant differences between groups. Twelve weeks of euenergetic diets with different dietary protein contents resulted in no significant weight loss in women with NWO. However, an HP diet significantly improved body composition (LBM, FM, BFP and WC) in this population.

Protein Intake Greater than the RDA Differentially Influences Whole-Body Lean Mass Responses to Purposeful Catabolic and Anabolic Stressors: A Systematic Review and Meta-analysis

Under stressful conditions such as energy restriction (ER) and physical activity, the RDA for protein of 0.8 g · kg-1 · d-1 may no longer be an appropriate recommendation. Under catabolic or anabolic conditions, higher protein intakes are proposed to attenuate the loss or increase the gain of whole-body lean mass, respectively. No known published meta-analysis compares protein intakes greater than the RDA with intakes at the RDA. Therefore, we conducted a systematic review and meta-analysis to assess the effects of protein intakes greater than the RDA, compared with at the RDA, on changes in whole-body lean mass. Three researchers independently screened 1520 articles published through August 2018 using the PubMed, Scopus, CINAHL, and Cochrane databases, with additional articles identified in published systematic review articles. Randomized, controlled, parallel studies ≥6 wk long with apparently healthy adults (≥19 y) were eligible for inclusion. Data from 18 studies resulting in 22 comparisons of lean mass changes were included in the final overall analysis. Among all comparisons, protein intakes greater than the RDA benefitted changes in lean mass relative to consuming the RDA [weighted mean difference (95% CI): 0.32 (0.01, 0.64) kg, n = 22 comparisons]. In the subgroup analyses, protein intakes greater than the RDA attenuated lean mass loss after ER [0.36 (0.06, 0.67) kg, n = 14], increased lean mass after resistance training (RT) [0.77 (0.23, 1.31) kg, n = 3], but did not differentially affect changes in lean mass [0.08 (-0.59, 0.75) kg, n = 7] under nonstressed conditions (no ER + no RT). Protein intakes greater than the RDA beneficially influenced changes in lean mass when adults were purposefully stressed by the catabolic stressor of dietary ER with and without the anabolic stressor of RT. The RDA for protein is adequate to support lean mass in adults during nonstressed states. This review was registered at www.crd.york.ac.uk/prospero as CRD 42018106532.

Personalized Nutrition Using PROCARDIO to Reduce Cardiometabolic Risk in the Academic Community: A Study Protocol with Preliminary Results

Background: Strategies of promotion, prevention and health care of individuals with cardiometabolic risk are necessary to control cardiovascular diseases.Objective: To describe a study design and present partial results of nutritional counseling in the Cardiovascular Health Care Program (PROCARDIO).Methods: PROCARDIO is a nutritional intervention program for students and workers or dependents of the Brazilian university academic community who are at risk of or have a cardiovascular disease (Brazilian Registry of Clinical Trials n° RBR-5n4y2g). Patients are submitted to nutritional clinical assessments involving anthropometry, biochemical analysis, sociodemographic and clinical, lifestyle and dietary data. Patients are provided with nutritional counseling, dietetic workshops and educational materials. In addition, nutritional following-ups are performed monthly.Results: The sample consisted of 296 patients (171 F/125 M, 27-56 years). The prevalence of individuals with excess body weight, dyslipidemia, diabetes and hypertension in the sample were 74.7% (n = 222), 79.1% (n = 235), 18.2% (n = 54) and 25.3% (n = 75), respectively. After three months of nutritional counseling, PROCARDIO users had decreased body fat, waist circumference, fasting blood glucose, total cholesterol and LDL-C (p < 0.05). Specifically, patients with diabetes exhibited reduced glycated hemoglobin concentrations (p < 0.05); those with dyslipidemia showed a reduction in total cholesterol, LDL-C and LDL/HDL (p < 0.05) concentrations; and those with excess body weight reduced waist circumference, waist-to-hip ratio, body fat, uric acid and total cholesterol/HDL-C ratios (p < 0.05).Conclusion: PROCARDIO patients concluded with a clinical-metabolic improvement regardless of chronic diseases after receiving nutritional counseling, thus highlighting the importance of individual actions and strategies to be based on personalized nutrition for achieving proposed therapeutic targets.

The independent associations of protein consumption with body fat and glycaemic control in adult Chinese

PURPOSE

High-protein diets were popular in weight control. However, the role of protein intake in adiposity and related metabolic conditions among general populations is not clear. We aimed to evaluate the associations of protein intake with adiposity and glycaemic control among adult Chinese in a nationwide population-based survey.

METHODS

The data were from China Health and Nutrition Survey 2009. A total of 9360 men and women aged 18 years or older were included. Body fat percentage was calculated using validated Chinese-specific equations. Dietary intake levels of macronutrients were evaluated by food-weighing approach combined with a 3-day food intake recall.

RESULTS

Averagely, our participants have 12.5% energy intake from dietary protein. With multivariate adjustment including total energy intake, the odds ratios (95% CIs) of excessive adiposity (body fat percentage ≥ 20/30% for men/women), and central obesity (waist circumference ≥ 90/80 cm for men/women) were 1.51 (1.30, 1.75) and 1.40 (1.21, 1.62), respectively, comparing extreme quintiles of relative protein intake, while fat and carbohydrate were not associated with adiposity indices. Moreover, higher relative protein intake was associated with elevated concentration of fasting glucose (β ± SE: 1.233 ± 0.583), fasting insulin (23.211 ± 9.191), glycated hemoglobin (1.057 ± 0.369), and insulin resistance indicated by homeostasis model assessment of insulin resistance (7.558 ± 2.928) (all P < 0.05). Further adjusting for body mass index attenuated the associations.

CONCLUSION

In Chinese adults, higher habitual protein consumption may be associated with higher adiposity and worse glycaemic control, independent of total energy intake.

Impact of a non-restrictive satiating diet on anthropometrics, satiety responsiveness and eating behaviour traits in obese men displaying a high or a low satiety phenotype

The aim of this study was to evaluate the impact of a non-restrictive satiating diet in men displaying various degrees of satiety efficiency. In all, sixty-nine obese men aged 41·5 (sd5·7) years were randomly assigned to a control (10–15, 55–60 and 30 % energy as protein, carbohydrate and lipid, respectively;n34) or satiating (20–25, 45–50 and 30–35 % energy as protein, carbohydrate and lipid, respectively;n35) diet for 16 weeks, and were classified as having a low (LSP) or high (HSP) satiety phenotype. Both diets were consumedad libitum. Changes in body weight, BMI, percent fat mass, waist circumference, satiety responsiveness and eating behaviour traits were assessed following the intervention. Dropout rates were higher in the control diet (44·1 %) compared with the satiating diet (8·6 %). Decreases in body weight, BMI and waist circumference were significant in both groups, yet HSP individuals lost more body weight than LSP individuals (P=0·048). Decreases in % fat mass were greater in the satiating diet (LSP: −2·1 (sd2·1) %;P<0·01 and HSP: −3·0 (sd2·5) %;P<0·001) compared with the control diet (LSP: −1·1 (sd2·5) % and HSP: −1·3 (sd2·6) %) (P=0·034). Satiety responsiveness was markedly improved in the satiating diet, whereas no significant changes were observed in the control group. Changes in dietary restraint (+3·3 (sd2·9) to +7·2 (sd5·5)), flexible control (+0·9 (sd1·4) to +2·3 (sd2·7)), rigid control (+2·2 (sd1·5) to +2·5 (sd2·8)), disinhibition (−2·8 (sd3·7) to −3·2 (sd2·6)) and susceptibility to hunger (−2·7 (sd4·1) to −4·6 (sd3·9)) were similar between the diets. Compared with the control diet, the satiating diet favoured adherence, decreased % fat mass and improved satiety responsiveness in both HSP and LSP individuals.

Use of Novel High-Protein Functional Food Products as Part of a Calorie-Restricted Diet to Reduce Insulin Resistance and Increase Lean Body Mass in Adults: A Randomized Controlled Trial

Significant reductions in insulin resistance (IR) can be achieved by either calorie restriction or by the increase of lean mass. However, calorie restriction usually results in significant loss of lean mass. A 6-week randomized controlled feeding trial was conducted to determine if a calorie-restricted, high-protein diet (~125 g protein/day consumed evenly throughout the day) using novel functional foods would be more successful for reducing IR in comparison to a conventional diet (~80 g protein/day) with a similar level of calorie restriction. Healthy adults (age 20-75 years; body mass index, 20-42 kg/m²) with raised triglyceride/high-density lipoprotein ratios were randomly assigned to the control group (CON: test foods prepared using gluten-free commercial pasta and cereal) or to the high-protein group (HPR: test foods prepared using novel high-protein pasta and cereal both rich in wheat gluten). Mean weight loss did not differ between groups (-2.7 ± 2.6 and -3.2 ± 3.0 kg for CON (n = 11) and HPR (n = 10) respectively, p = 0.801); however, the 6-week change in fat-free mass (FFM) differed significantly between groups (-0.5 ± 1.5 and +1.5 ± 3.8 kg for CON and HPR respectively, p = 0.008). IR improved in HPR vs. CON participants (homeostasis model assessment-estimated insulin resistance [HOMAIR] change: -1.7 ± 1.4 and -0.7 ± 0.7 respectively; p = 0.020). The change in HOMA-IR was related to the change in FFM among participants (r = -0.511, p = 0.021). Thus, a high-protein diet using novel functional foods combined with modest calorie restriction was 140% more effective for reducing HOMA-IR in healthy adults compared to a lower protein, standard diet with an equal level of calorie restriction.

Dairy Attenuates Weight Gain to a Similar Extent as Exercise in Rats Fed a High-Fat, High-Sugar Diet

OBJECTIVE

To compare the individual and combined effects of dairy and endurance exercise training in reducing weight gain and adiposity in a rodent model of diet-induced obesity.

METHODS

An 8-week feeding intervention of a high-fat, high-sugar diet was used to induce obesity in male Sprague-Dawley rats. Rats were then assigned to one of four groups for 6 weeks: (1) casein sedentary (casein-S), (2) casein exercise (casein-E), (3) dairy sedentary (dairy-S), and (4) dairy exercise (dairy-E). Rats were exercise trained by treadmill running 5 d/wk.

RESULTS

Dairy-E prevented weight gain to a greater extent than either dairy or exercise alone. Adipose tissue and liver mass were reduced to a similar extent in dairy-S, casein-E, and dairy-E groups. Differences in weight gain were not explained by food intake or total energy expenditure. The total amount of lipid excreted was greater in the dairy-S compared to casein-S and dairy-E groups.

CONCLUSIONS

This study provides evidence that dairy limits weight gain to a similar extent as exercise training and the combined effects are greater than either intervention alone. While exercise training reduces weight gain through increases in energy expenditure, dairy appears to increase lipid excretion in the feces.

Acute and Long-Term Impact of High-Protein Diets on Endocrine and Metabolic Function, Body Composition, and Exercise-Induced Adaptations

BACKGROUND

High-protein diets have been shown to improve body composition through alterations in satiety, muscle protein synthesis, and the thermic effect of food.

AIM

Given these findings, the purpose of this review is to discuss the integration of the specific hormonal and metabolic effects of high-protein diets following both acute and long-term usage, especially with regard to body composition.

METHODS

Full-text articles were obtained through PubMed by using the terms "high-protein diet and body composition," "high-protein diet and exercise," "high-protein diet risk," "high-protein diet side effects," "protein quality PDCAAS," "RDA for protein," and "daily protein recommendation." Articles were initially screened according to their title and abstract; careful evaluation of the full manuscripts was then used to identify relevant articles.

RESULTS

The higher satiety exerted by high-protein diets is generated through increments in anorexigenic, as well as decrements in orexigenic hormones. Improvements in muscle mass are achieved by activation of muscle protein synthesis acting through the mTOR pathway. High thermic effect of food is caused due to necessary deamination, gluconeogenesis, and urea synthesis caused by high-protein diets. Interestingly, high-protein diets in both hypo- and normocaloric conditions have shown to improve body composition, whereas in combination with hypercaloric conditions does not seem to increase fat mass, when the excess energy comes from protein.

CONCLUSIONS

High protein diets effectively improve body composition by acting through different pathways.

Effects of Dietary Macronutrient Composition on FNDC5 and Irisin in Mice Skeletal Muscle

BACKGROUND

Fibronectin type III domain containing 5 (FNDC5) and its protein product Irisin are therapeutic targets for obesity-associated disorders. Irisin plays an important role in energy regulation, inducing browning of white adipocytes, and improving obesity. We aimed to investigate the association between muscle Irisin expression and dietary quality.

METHODS

Twenty-eight female mice were divided into four groups and fed the following experimental diets for 60 days: standard diet (SD), high-carbohydrate diet (HCD), high-fat diet (HFD), and high-protein diet (HPD). We evaluated body weight, food intake, serum total cholesterol, triacylglycerol, and glucose. We also performed glucose tolerance and insulin sensitivity tests. Expression of FNDC5 was evaluated by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) of soleus muscle. Western blot was used to assess Irisin protein expression.

RESULTS

The major finding of the present study was that HFD and HCD were associated with a downregulation of FNDC5. In addition to these results, we noted a significant reduction in skeletal muscle Irisin level. HPD prevented reductions of both FNDC5 and Irisin levels, as well as increased brown adipose tissue, compared to the control group.

CONCLUSIONS

In conclusion, we observed that the HPD type of diet can change both FNDC5 expression and Irisin levels. Thus, the HPD might be the most appropriate diet to achieve high amounts of Irisin, a target molecule for the treatment of obesity and its co-morbidities.

Comparison of Very Low Energy Diet Products Available in Australia and How to Tailor Them to Optimise Protein Content for Younger and Older Adult Men and Women

Very low energy diets (VLED) are efficacious in inducing rapid weight loss but may not contain adequate macronutrients or micronutrients for individuals with varying nutritional requirements. Adequate protein intake during weight loss appears particularly important to help preserve fat free mass and control appetite, and low energy and carbohydrate content also contributes to appetite control. Therefore, the purpose of this study was to compare the nutritional content (with a focus on protein), nutritional adequacy and cost of all commercially-available VLED brands in Australia. Nutritional content and cost were extracted and compared between brands and to the Recommended Dietary Intake (RDI) or adequate intake (AI) of macronutrients and micronutrients for men and women aged 19-70 years or >70 years. There was wide variability in the nutritional content, nutritional adequacy and cost of VLED brands. Most notably, even brands with the highest daily protein content, based on consuming three products/day (KicStart™ and Optislim(®), ~60 g/day), only met estimated protein requirements of the smallest and youngest women for whom a VLED would be indicated. Considering multiple options to optimise protein content, we propose that adding pure powdered protein is the most suitable option because it minimizes additional energy, carbohydrate and cost of VLEDs.

Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis

CONTEXT

The impact of dietary protein on body composition changes after older adults purposefully lose weight requires systematic evaluation

OBJECTIVE

: This systematic review and meta-analysis assessed the effects of protein intake (< 25% vs ≥ 25% of energy intake or 1.0 g/kg/d) on energy restriction-induced changes in body mass, lean mass, and fat mass in adults older than 50 years.

DATA SOURCES

PubMed, Cochrane, Scopus, and Google Scholar were searched using the keywords "dietary proteins," "body composition," "skeletal muscle," and "muscle strength."

STUDY SELECTION

Two researchers independently screened 1542 abstracts.

DATA EXTRACTION

Information was extracted from 24 articles.

DATA SYNTHESIS

Twenty randomized control trials met the inclusion criteria.

CONCLUSION

Older adults retained more lean mass and lost more fat mass during weight loss when consuming higher protein diets.

Dietary Patterns of Young Females and Their Association With Waist Circumference as a Health Index in Northwest of Iran, 2007

Background:

Despite the higher prevalence of overweight and obesity among young people in western countries, the 50th and 95th percentile ranks for waist circumference in the Iranian young Females are higher than those of the western ones.

Objectives:

Identifying major dietary patterns in Iranian young females, which associate with central obesity, can probably explain the difference between Iranian young females’ pattern and those of their western peers regarding obesity.

Patients and Methods:

In the current cross-sectional study, a total of 257 young females aged 11 - 15 years old from Talaat Intelligent Guidance School, Tabriz, Iran (2007) were selected for the study using non-probability simple sampling method. Then, usual dietary intakes of all subjects were evaluated by a food frequency questionnaire and anthropometric measurements such as weight, height, waist circumference, and Body Mass Index (BMI) using the standard protocols. Data were analyzed by inferential statistics (One-way ANOVA, Tukey test for Post-Hoc Analysis, Chi-square test, age-adjusted means, analysis of covariance with Bonferroni correction, correlation and partial correlation) by SPSS software.

Results:

In the current study, six major dietary patterns were extracted using factor analysis method. Before and after controlling the age, subjects in the upper tertile of the Iranian Central Obesity Making Dietary Pattern (rich in cruciferous vegetables, green leafy vegetables, soft drinks, tomatoes, other vegetables and vegetable oils) had larger waist circumference in comparison with the ones in the lower tertile (before controlling for age: 64.2 ± 9 vs. 61.6 ± 7 P = 0.03; after: 64.5 ± 0.8 vs. 61.5 ± 0.8, P = 0.009). However in lacto vegetarian dietary pattern (rich in legumes, potato, other vegetables, dough, high-fat dairy products and margarine), individuals in the upper tertile had significantly lower weight, waist circumference and body mass index (BMI) in comparison with the ones in the lower tertile (weight: 44.9 ± 9.3 vs. 51.4 ± 10.6, P < 0.01; WC: 59.9 ± 8 vs. 64 ± 7.9, P < 0.01; BMI: 18.6 ± 3.1 vs. 20.6 ± 3.5, P < 0.01).

Conclusions:

The current study findings suggest that the Iranian Central Obesity Making Dietary Pattern is directly associated with waist circumference (marker of central obesity), while lacto vegetarian dietary pattern is reversely associated with weight, waist circumference and BMI. Special obesity pattern in Iranian young females can be justified by Iranian Central Obesity Making Dietary Pattern”.

Protein intake and muscle function in older adults

PURPOSE OF REVIEW

We provide an update on the recent advances in nutrition research regarding the role of protein intake in the development and treatment of sarcopenia of aging.

RECENT FINDINGS

Specific muscle mass, strength and function cut-points for the diagnosis of sarcopenia have been identified. There is mounting evidence, as highlighted by multiple consensus statements, that the Recommended Dietary Allowance (0.8 g/kg body weight) may be inadequate to promote optimal health in older adults. Recent research indicates that in addition to total daily protein intake the timing of protein intake is also important to best stimulate muscle protein synthesis, and maintain muscle mass and function in older adults.

SUMMARY

Recent evidence suggests that the Recommended Dietary Allowance for protein is inadequate, and that the timing and distribution of protein consumption throughout daily meals may be as important as the total quantity. Research has continued to advance our understanding of protein's effects on muscle metabolism; however, there remains a need for large, long-term, randomized clinical trials examining whether the positive effects of dietary protein on muscle metabolism seen in acute studies will translate over the long term into gains of muscle mass, function, and the overall health of older adults.

Higher-protein diets are associated with higher HDL cholesterol and lower BMI and waist circumference in US adults

BACKGROUND

Protein intake above the RDA attenuates cardiometabolic risk in overweight and obese adults during weight loss. However, the cardiometabolic consequences of consuming higher-protein diets in free-living adults have not been determined.

OBJECTIVE

This study examined usual protein intake [g/kg body weight (BW)] patterns stratified by weight status and their associations with cardiometabolic risk using data from the NHANES, 2001-2010 (n = 23,876 adults ≥19 y of age).

METHODS

Linear and decile trends for association of usual protein intake with cardiometabolic risk factors including blood pressure, glucose, insulin, cholesterol, and triglycerides were determined with use of models that controlled for age, sex, ethnicity, physical activity, poverty-income ratio, energy intake (kcal/d), carbohydrate (g/kg BW) and total fat (g/kg BW) intake, body mass index (BMI), and waist circumference.

RESULTS

Usual protein intake varied across deciles from 0.69 ± 0.004 to 1.51 ± 0.009 g/kg BW (means ± SEs). Usual protein intake was inversely associated with BMI (-0.47 kg/m(2) per decile and -4.54 kg/m(2) per g/kg BW) and waist circumference (-0.53 cm per decile and -2.45 cm per g/kg BW), whereas a positive association was observed between protein intake and HDL cholesterol (0.01 mmol/L per decile and 0.14 mmol/L per g/kg BW, P < 0.00125).

CONCLUSIONS

Americans of all body weights typically consume protein in excess of the RDA. Higher-protein diets are associated with lower BMI and waist circumference and higher HDL cholesterol compared to protein intakes at RDA levels. Our data suggest that Americans who consume dietary protein between 1.0 and 1.5 g/kg BW potentially have a lower risk of developing cardiometabolic disease.

Insufficient Protein Intake Is Associated With Increased Mortality in 630 Patients With Cirrhosis Awaiting Liver Transplantation

BACKGROUND

For patients awaiting liver transplantation, we aimed to determine the prevalence and predictors of insufficient protein intake as well as to determine whether very low protein intake was an independent predictor of malnutrition and mortality.

MATERIALS AND METHODS

Adults with cirrhosis who were activated on our local liver transplant waiting list between January 2000 and October 2009 were included. Estimated protein intake was derived from dietary records. Patients with incomplete dietary records were excluded. Multivariable logistic regression and competing risk analysis were used.

RESULTS

Of 742 potential patients, 112 were excluded due to insufficient data, leaving 630 patients for evaluation. Mean protein intake was 1.0 ± 0.36 g/kg/d and only 24% of patients met the expert consensus recommended threshold of > 1.2 g/kg of protein per day. Very low protein intake (< 0.8 g/kg/d) was associated with worse liver disease severity (as measured by Child-Pugh or MELD). Protein intake below 0.8 g/kg/d was an independent predictor both of malnutrition as measured by the subjective global assessment (adjusted odds ratio [95% confidence interval (CI)]: 2.0 [1.3-3.0]) and of transplant waiting list mortality (adjusted hazard ratio [95% CI]: 1.8 [1.2-2.7]).

CONCLUSION

In this large cohort of liver transplant waitlisted patients, very low protein intake was prevalent and independently associated with malnutrition and mortality. Unlike many other prognostic factors, protein intake is potentially modifiable. Prospective studies are warranted to evaluate the effect of targeted protein repletion on clinically relevant outcomes such as muscle mass, muscle function, immune function, and mortality.

Whey protein preloads are more beneficial than soy protein preloads in regulating appetite, calorie intake, anthropometry, and body composition of overweight and obese men

High-protein diets exert beneficial effects on appetite, anthropometry, and body composition; however, the effects of protein preloads depend on the amount, type, and time of consumption. Therefore, we hypothesized that long-term supplemental preloads of whey protein concentrate (WPC) and soy protein isolate (SPI) consumed 30 minutes before the largest meal would decrease appetite, calorie intake (CI), and anthropometry and improve body composition in overweight and obese men in free-living conditions. The subjects included 45 men with a body mass index between 25 and 40 kg/m(2) and who were randomly allocated to either the WPC (n = 26) or SPI (n = 19) groups. For 12 weeks, the subjects consumed 65 g WPC or 60 g SPI that was dissolved in 500 mL water 30 minutes before their ad libitum lunch. Appetite, CI, anthropometry, and body composition were assessed before and after the study and biweekly throughout. After 12 weeks, mean changes between the groups were significant for appetite (P = .032), CI (P = .045), anthropometry (body weight [P = .008], body mass index [P = .006], and waist circumference), and body composition (body fat mass and lean muscle [P < .001]). Relative to baseline, within-group mean changes from WPC were significant for appetite, CI, anthropometry, and body composition (P < .001). In the SPI group, mean changes were significant, relative to baseline, for all variables except lean muscle (P = .37). According to this 12-week study, WPC preloads conducted 30 minutes prior to the ad libitum main meal exerted stronger beneficial effects than did SPI preloads on appetite, CI, anthropometry, and body composition of free-living overweight and obese men.

Stage of change and motivation to healthy diet and habitual physical activity in type 2 diabetes

Lifestyle changes to healthy diet (HD) and habitual physical activity (HPA) are recommended in type 2 diabetes mellitus (T2DM). Yet, for most people with diabetes, it may be difficult to start changing. We investigated the stage of change toward healthier lifestyles according to Prochaska's model, and the associated psychological factors in T2DM patients, as a prerequisite to improve strategies to implement behavior changes in the population. A total of 1,353 consecutive outpatients with T2DM attending 14 tertiary centers for diabetes treatment completed the validated EMME-3 questionnaire, consisting of two parallel sets of instruments to define the stage of change for HD and HPA, respectively. Logistic regression was used to determine the factors associated with stages that may hinder behavioral changes. A stage of change favoring progress to healthier behaviors was more common in the area of HD than in HPA, with higher scores in action and maintenance. Differences were observed in relation to gender, age and duration of disease. After adjustment for confounders, resistance to change toward HD was associated with higher body mass index (BMI) (odds ratio (OR) 1.05; 95 % confidence interval (CI) 1.02-1.08). Resistance to improve HPA also increased with BMI (OR 1.06; 95 % CI 1.03-1.10) and decreased with education level (OR 0.74; 95 % CI 0.64-0.92). Changing lifestyle, particularly in the area of HPA, is not perceived as an essential part of treatment by many subjects with T2DM. This evidence must be considered when planning behavioral programs, and specific interventions are needed to promote adherence to HPA.

Race and gender disparities in nutrient intake are not related to metabolic syndrome in 20- to 59-year-old US adults

BACKGROUND

The goal of this study was to examine the relationship between macronutrient and micronutrient intake and metabolic syndrome within race and gender cohorts of young US adults.

METHODS

The 2007-2010 National Health and Nutrition Examination Survey (NHANES) data for adults (n=2440) aged 20-59 were analyzed. Two 24-hr dietary recalls were used to measure intake of total calories, macronutrients, and 20 vitamins and minerals. Metabolic syndrome and its components were defined by the National Heart, Lung and Blood Institute criteria. Differences in statistical tests were noted when significant at P<0.05.

RESULTS

Prevalence of metabolic syndrome among 20- to 59-year-old adults was 30.4% [95% confidence interval 27.6-33.2]. Among cohorts, metabolic syndrome was highest in black women and white men, and lowest in black men and white women. Regression analysis indicated that no macronutrients were associated with greater risk of metabolic syndrome. For relative macronutrient intake, men with metabolic syndrome consumed more polyunsaturated fats, whereas women with metabolic syndrome consumed more total, saturated and monounsaturated fats and less fiber and starch than women without metabolic syndrome. Among races, white men and women consumed greater absolute quantities of all macronutrients except carbohydrates and sugar. Micronutrient intake was greatest for white men and women; women without metabolic syndrome had greater micronutrient adequacy than women with metabolic syndrome.

CONCLUSION

Nutrient intake varied between race/gender cohorts; however, there were few clinically significant differences in nutrient intake between those with and without metabolic syndrome. Diet may be marginally related to diagnosis of metabolic syndrome.

The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals

BACKGROUND

The consumption of dietary protein is important for resistance-trained individuals. It has been posited that intakes of 1.4 to 2.0 g/kg/day are needed for physically active individuals. Thus, the purpose of this investigation was to determine the effects of a very high protein diet (4.4 g/kg/d) on body composition in resistance-trained men and women.

METHODS

Thirty healthy resistance-trained individuals participated in this study (mean ± SD; age: 24.1 ± 5.6 yr; height: 171.4 ± 8.8 cm; weight: 73.3 ± 11.5 kg). Subjects were randomly assigned to one of the following groups: Control (CON) or high protein (HP). The CON group was instructed to maintain the same training and dietary habits over the course of the 8 week study. The HP group was instructed to consume 4.4 grams of protein per kg body weight daily. They were also instructed to maintain the same training and dietary habits (e.g. maintain the same fat and carbohydrate intake). Body composition (Bod Pod®), training volume (i.e. volume load), and food intake were determined at baseline and over the 8 week treatment period.

RESULTS

The HP group consumed significantly more protein and calories pre vs post (p < 0.05). Furthermore, the HP group consumed significantly more protein and calories than the CON (p < 0.05). The HP group consumed on average 307 ± 69 grams of protein compared to 138 ± 42 in the CON. When expressed per unit body weight, the HP group consumed 4.4 ± 0.8 g/kg/d of protein versus 1.8 ± 0.4 g/kg/d in the CON. There were no changes in training volume for either group. Moreover, there were no significant changes over time or between groups for body weight, fat mass, fat free mass, or percent body fat.

CONCLUSIONS

Consuming 5.5 times the recommended daily allowance of protein has no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen. This is the first interventional study to demonstrate that consuming a hypercaloric high protein diet does not result in an increase in body fat.

Dietary protein and muscle in older persons

PURPOSE OF REVIEW

The purpose of this study is to highlight recent advances in nutrition and protein research that have the potential to improve health outcomes and status in ageing 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 Recommended Dietary Allowance 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 the 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. Although 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.

Dietary strategies to reduce metabolic syndrome

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities characterized by central obesity, dyslipidemias, hypertension, high fasting glucose, chronic low-grade inflammation and oxidative stress. This condition has become an increasing problem in our society where about 34 % of adults are diagnosed with MetS. In parallel with the adult situation, a significant number of children present lipid abnormalities and insulin resistance, which can be used as markers of MetS in the pediatric population. Changes in lifestyle including healthy dietary regimens and increased physical activity should be the first lines of therapy to decrease MetS. In this article, we present the most recent information on successful dietary modifications that can reduce the parameters associated with MetS. Successful dietary strategies include energy restriction and weight loss, manipulation of dietary macronutrients--either through restriction of carbohydrates, fat, or enrichment in beneficial fatty acids, incorporation of functional foods and bioactive nutrients, and adherence to dietary and lifestyle patterns such the Mediterranean diet and diet/exercise regimens. Together, the recent findings presented in this review serve as evidence to support the therapeutic treatment of MetS through diet.

Regional, but not total, body composition changes in overweight and obese adults consuming a higher protein, energy-restricted diet are sex specific

Secondary analyses of data from 2 studies were used to assess the effects of protein intake and sex on diet-induced changes in body composition. The primary hypothesis was that the changes of body composition via energy restriction (ie, lean body mass [LBM], fat mass [FM], and bone) would be sex and diet specific. For 12 weeks, 43 male (study 1) and 45 female (study 2) overweight and obese adults consumed an energy-deficit diet (750 kcal/d less than energy needs) containing either 0.8 (normal protein [NP], 21 men and 23 women) or 1.4 g protein∙kg(-1)∙d(-1) (high protein [HP], 22 men and 22 women). Body composition measurements were performed at preintervention and postintervention. Over time, all research participants lost weight, LBM, and FM. Independent of protein intake, the men lost more LBM in the trunk (-0.9 vs -0.5 kg) and less in the legs (-1.5 vs -1.1 kg) compared with the women (P < .05). Independent of sex, the HP group lost less LBM in the trunk and legs than the NP group. These sex and protein intake responses resulted in the NP men losing the most LBM in the legs and the NP women losing the most LBM in the trunk. Over time, men lost more FM (-5.0 vs -3.9 kg) from the trunk and less from legs (-1.7 vs -2.1 kg) than women (P < .05), which resulted in a greater decrease of the android-to-gynoid fat ratio for the men. Protein intake did not influence these sex-specific responses or have any independent effects on changes in FM. In addition, protein intake did not influence bone mineral density responses over time; bone mineral density was reduced in women, but not in men. These findings indicate that higher protein intake during weight loss promotes the retention of LBM in both the trunk and legs despite the sex-specific changes in these body regions.