Effects of protein intake and gender on body composition changes: a randomized clinical weight loss trial.

UNLABELLED: Limited data on sex differences in body composition changes in response to higher protein diets (PRO) compared to higher carbohydrate diets (CARB) suggest that a PRO diet helps preserve lean mass (LM) in women more so than in men. OBJECTIVE: To compare male and female body composition responses to weight loss diets differing in macronutrient content. DESIGN: Twelve month randomized clinical trial with 4mo of weight loss and 8mo weight maintenance. SUBJECTS: Overweight (N = 130; 58 male (M), 72 female (F); BMI = 32.5 ± 0.5 kg/m2) middle-aged subjects were randomized to energy-restricted (deficit ~500 kcal/d) diets providing protein at 1.6 g.kg-1.d-1 (PRO) or 0.8 g.kg-1.d-1 (CARB). LM and fat mass (FM) were measured using dual X-ray absorptiometry. Body composition outcomes were tested in a repeated measures ANOVA controlling for sex, diet, time and their two- and three-way interactions at 0, 4, 8 and 12mo. RESULTS: When expressed as percent change from baseline, males and females lost similar amounts of weight at 12mo (M:-11.2 ± 7.1 %, F:-9.9 ± 6.0 %), as did diet groups (PRO:-10.7 ± 6.8 %, CARB:-10.1 ± 6.2 %), with no interaction of gender and diet. A similar pattern emerged for fat mass and lean mass, however percent body fat was significantly influenced by both gender (M:-18.0 ± 12.8 %, F:-7.3 ± 8.1 %, p < 0.05) and diet (PRO:-14.3 ± 11.8 %, CARB:-9.3 ± 11.1 %, p < 0.05), with no gender-diet interaction. Compared to women, men carried an extra 7.0 ± 0.9 % of their total body fat in the trunk (P < 0.01) at baseline, and reduced trunk fat during weight loss more than women (M:-3.0 ± 0.5 %, F:-1.8 ± 0.3 %, p < 0.05). Conversely, women carried 7.2 ± 0.9 % more total body fat in the legs, but loss of total body fat in legs was similar in men and women. CONCLUSION: PRO was more effective in reducing percent body fat vs. CARB over 12mo weight loss and maintenance. Men lost percent total body fat and trunk fat more effectively than women. No interactive effects of protein intake and gender are evident.

The effects of a higher protein intake during energy restriction on changes in body composition and physical function in older women.

BACKGROUND: The purpose of this double-blind randomized clinical trial was to compare the relative effectiveness of a higher protein and conventional carbohydrate intake during weight loss on body composition and physical function in older women. METHODS: Thirty-one overweight or obese, postmenopausal women (mean ± SD: age 65.2 ± 4.6 years, body mass index 33.7 ± 4.9 kg/m(2)) were prescribed a reduced calorie diet (1,400 kcal/day; 15%, 65%, 30% energy from protein, carbohydrate, and fat, respectively) and randomly assigned to 2 × 25 g/day whey protein (PRO n = 15) or maltodextrin (CARB n = 16) supplementation for 6 months. Lean soft tissue (LST) via dual-energy X-ray absorptiometry; thigh muscle, subcutaneous adipose tissue (SAT), and intermuscular adipose tissue with magnetic resonance imaging; knee strength with isokinetic dynamometry; balance and physical function with a battery of performance tests. RESULTS: PRO lost more weight than CARB (-8.0% ± 6.2%, -4.1% ± 3.6%, p = .059; respectively). Changes in LST, %LST, and strength, balance, or physical performance measures did not differ between groups (all p > .05). Weight to leg LST ratio improved more in PRO versus CARB (-4.6 ± 3.6%, -1.8 ± 2.6%, p = .03). PRO lost 4.2% more muscle (p = .01), 10.9% more SAT (p = .02), and 8.2% more intermuscular adipose tissue (p = .03) than CARB. Relative to thigh volume changes, PRO gained 5.8% more muscle (p = .049) and lost 3.8% greater SAT (p = .06) than CARB. Weight to leg LST ratio (r(2) = .189, p = .02) and SAT (r(2) = .163, p = .04) predicted improved up and go, relative muscle (r(2) = .238, p = .01) and SAT (r(2) = .165, p = .04) predicted improved transfer test, and %LST predicted improved balance (r(2) = .179, p = .04). CONCLUSIONS: A higher protein intake during caloric restriction maintains muscle relative to weight lost, which in turn enhances physical function in older women.

Effects of paraplegia on cardiac autonomic regulation during static exercise.

OBJECTIVES: The aim of this study was to examine whether autonomic modulation of heart rate as measured by heart rate variability and heart rate complexity at rest and during static handgrip exercise differs between individuals with and without paraplegia. This study also examined the relationships between heart rate complexity and heart rate variability parameters. DESIGN: Heart rate variability and complexity were evaluated in 20 individuals with paraplegia and in 20 individuals without paraplegia during 3 mins of rest and 2 mins of static handgrip exercise at 30% of maximum isometric strength. Spectral decomposition of heart rate variability was used to obtain total power, power in low-frequency and high-frequency ranges, and the ratio of low- to high-frequency power. Heart rate complexity was quantified with sample entropy, a measure of irregularity of the beat-to-beat time series. RESULTS: Sample entropy was lower (P < 0.05) at rest and during exercise in participants with paraplegia. Total, high-, and low-frequency powers as well as the ratio of low- to high-frequency power did not differ between groups. Sample entropy did not significantly correlate with low- and high-frequency powers or their ratio. CONCLUSIONS: Individuals with paraplegia show lower heart rate complexity at rest and during static exercise. This finding may have implications for cardiovascular morbidity in persons with paraplegia. Heart rate complexity may provide unique information regarding cardiac autonomic modulation, different from that provided by traditional heart rate variability measures.

Assessing calcium intake in postmenopausal women.

INTRODUCTION: Because foods fortified with calcium are increasingly available, the calcium content of calcium-fortified foods may not be adequately captured in traditional assessments of dietary intake, such as dietary records analyzed with commercially available software. The primary objective of our study was to design and test a calcium-focused food frequency questionnaire (CFFFQ) including foods naturally rich in calcium and calcium-fortified foods. Secondary objectives were to review calcium sources and adequacy of intake in black and in white postmenopausal women. METHODS: We studied a convenience sample of 46 black and 139 white postmenopausal women (mean [SD] age 69.4 [5.8] years). Participants completed a multiple-pass interview for 24-hour recall of foods eaten and the 46-item CFFFQ. RESULTS: The correlation between measures for total daily calcium intake was moderately strong (r = 0.53, P < .001). The CFFFQ estimated greater total daily calcium intake than did the 24-hour recall (mean [SD], 1,021 [624] mg/d vs 800 [433] mg/d, P < .001). As daily calcium intake increased, the 24-hour recall increasingly underreported calcium (r = 0.41, P < .001) compared with the CFFFQ. Cross-tabulation and Chi2 analyses found that the CFFFQ had greater specificity for lower calcium intakes. For calcium classified by food groups, there was moderate correlation for dairy (r = 0.56, P < .001) and fruits (r = 0.43, P < .001). The CFFFQ overestimated mean total calcium compared with the 24-hour recall by 221 mg/d (P < .001), including within racial groups (195 mg/d for black women, P = .04, and 229 mg/d for white women, P < .001). Dairy was the primary calcium source for both groups (55% of intake for black women and 57% of intake for white women). CONCLUSION: The CFFFQ can be used to identify postmenopausal women with inadequate calcium intakes (<800 mg/d) and to identify key sources of dietary calcium. Older black women consume less daily calcium than do older white women.

Bone health in ambulatory individuals with multiple sclerosis: impact of physical activity, glucocorticoid use, and body composition.

This study examined the relationships among physical activity, glucocorticoid use, body composition, and bone health in ambulatory women with multiple sclerosis (MS). Twenty-nine white women (mean +/- standard deviation: age 45.1 +/- 9.0 yr, Expanded Disability Status Scale 2.9 +/- 1.2) diagnosed with MS were assessed for whole body (WB), proximal femur (PF) and lumbar spine (LS) bone status (bone mineral content [BMC], bone mineral density [BMD], and quantitative ultrasound index [QUI] by calcaneal quantitative ultrasound) and body composition by dual energy X-ray absorptiometry; for physical activity by pedometer and accelerometer; and for glucocorticoid medication exposure by self-report. Accelerometer counts were related to PF BMC (r = 0.50, p = 0.010) when we controlled for age, fat and lean mass, MS disease duration, and glucocorticoid use. Glucocorticoid use was not associated with bone measures. When we controlled for age and fat mass, lean mass was associated with WB BMC (r = 0.41, p = 0.04), PF BMC (r = 0.61, p = 0.001), and speed of sound (SOS) (r = 0.44, p = 0.02), whereas fat mass was associated with SOS and QUI (r =0.43, p = 0.03, and r = 0.44, p = 0.02, respectively). Lean mass was an independent predictor of WB BMC ( p = 0.04) and PF BMC ( p = 0.001), whereas fat mass was an independent predictor of LS BMD (p = 0.05). In conclusion, physical activity and lean mass are associated with femoral bone mass in women with MS who are ambulatory.

Environmental barriers to and availability of healthy foods for people with mobility disabilities living in urban and suburban neighborhoods.

OBJECTIVE: To assess the impact of the built environment on access to healthy foods for people with mobility disabilities by measuring wheelchair accessibility of grocery stores and availability of healthy affordable foods. DESIGN: A survey consisting of 87 questions. SETTING: A low-income, multiracial urban Chicago neighborhood with a 3-mile radius was compared with a suburban neighborhood of the same size in which the population is similar in income level and racial distribution. PARTICIPANTS: Not applicable. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Accessibility issues outside and within grocery stores and the availability of healthy affordable food items in these grocery stores. RESULTS: The urban area had more stores (n=48) than the suburban area (n=34); however, only 46% of urban stores had an entrance that would allow an individual requiring a ramp or level entrance to gain access compared with 88% of suburban stores (P<.001). Wheelchair accessibility characteristics of grocery and convenience stores did not differ between the urban and suburban areas. The availability of healthy affordable foods in urban and suburban stores was relatively low, with only 33% to 40% of the 18 items available, and did not differ between urban and suburban stores. CONCLUSIONS: People with mobility impairments are at a disadvantage in maintaining healthy food choices because of limited access to stores and healthy foods.

Elevated C-reactive protein associated with decreased high-density lipoprotein cholesterol in men with spinal cord injury.

OBJECTIVES: To determine if people with spinal cord injury (SCI) have elevated C-reactive protein (CRP), to examine the association of CRP with high-density lipoprotein cholesterol (HDL-C), and to assess the influence of completeness and level of injury on these parameters. DESIGN: Cross-sectional. SETTING: Urban university. PARTICIPANTS: Men with SCI (n=129) who were free of infection and/or recent anti-inflammatory medication use as well as their 1:1 age- and race-matched able-bodied counterparts from the 1999-2002 National Health and Nutrition Examination Surveys. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: High CRP was defined as 3 mg/L or higher and low HDL-C as less than 1.04 mmol/L. RESULTS: Men with SCI were more likely to have high CRP (odds ratio [OR]=2.29; 95% confidence interval [CI], 1.33-3.95) and low HDL-C (OR=1.81; 95% CI, 1.01-3.27). The OR for low HDL-C in SCI was no longer significant when high CRP was controlled. CRP was higher in complete versus incomplete injury (median, 3.7 mg/L vs 1.2mg/L; P=.005), and this elevation was independent of age, smoking, physical activity, waist circumference, and weight. No conclusion can be made on the association of injury level and CRP because of a lack of power. CONCLUSIONS: The elevated CRP, possibly the major risk factor, together with decreased HDL-C may contribute to greater incidence for cardiovascular disease in the SCI population.

A positive association of lumbar spine bone mineral density with dietary protein is suppressed by a negative association with protein sulfur.

Dietary protein is theorized to hold both anabolic effects on bone and demineralizing effects mediated by the diet acid load of sulfate derived from methionine and cysteine. The relative importance of these effects is unknown but relevant to osteoporosis prevention. Postmenopausal women (n = 161, 67.9 +/- 6.0 y) were assessed for areal bone mineral density (aBMD) of lumbar spine (LS) and total hip (TH) using dual X-ray absorptiometry, and dietary intakes of protein, sulfur-containing amino acids, and minerals using a USDA multiple-pass 24-h recall. The acidifying influence of the diet was estimated using the ratio of protein:potassium intake, the potential renal acid load (PRAL), and intake of sulfate equivalents from protein. aBMD was regressed onto protein intake then protein was controlled for estimated dietary acid load. A step-down procedure assessed potential confounding influences (weight, age, physical activity, and calcium and vitamin D intakes). Protein alone did not predict LS aBMD (P = 0.81); however, after accounting for a negative effect of sulfate (beta = -0.28; P < 0.01), the direct effect of protein intake was positive (beta = 0.22; P = 0.04). At the TH, protein intake predicted aBMD (beta = 0.18; P = 0.03), but R2 did not improve with adjustment for sulfate (P = 0.83). PRAL and the protein:potassium ratio were not significant predictors of aBMD. Results suggest that protein intake is positively associated with aBMD, but benefit at the LS is offset by a negative impact of the protein sulfur acid load. If validated experimentally, these findings harmonize conflicting theories on the role of dietary protein in bone health.

Simulated change in body fatness affects Hologic QDR 4500A whole body and central DXA bone measures.

Changes in body fatness may impact the accuracy of dual energy X-ray absorptiometry (DXA) measures of bone mineral content (BMC) and bone mineral density (BMD). The aim of this study was to determine if DXA can accurately assess BMC and BMD with changes in exogenous fat (lard) placed to simulate weight change. Whole body (WB), lumbar spine (LS), and proximal femur (PF) DXA scans (Hologic QDR 4500A) were performed on 30 elderly (52-83 yr) and 60 young (18-40 yr) individuals (i.e., 45 females and 45 males) of varying body mass index (mean+/-standard deviation: 26.1+/-4.9 kg/m2). When scans were repeated with lard packets (2.54 cm thick, 25.4x17.8 cm, 1 kg), WB BMD decreased 1.1% and 1.6% after chest and thigh packet placement, respectively (p=0.001), PF BMD increased 0.7% (p=0.02) and LS BMD decreased 1.6% (p=0.001) primarily due to a 2.2% reduction in LS BMC (p<0.001). Initial LS BMC and trunk mass were related to error in LS BMC measures due to lard-loading (r=0.64 and 0.45, respectively, p<0.001). We conclude that on average simulated weight change minimally impacts PF bone measures and moderately impacts WB and LS bone measures; however, individual variability in measurement error was noteworthy and may be impacted by body thickness.

Older black women differ in calcium intake source compared to age- and socioeconomic status-matched white women.

Racial disparity in osteoporosis between older black and white women is well established; however, less is known regarding daily dietary and supplemental calcium intake in these populations. Moreover, racial differences in calcium intake are confounded by differences in socioeconomic status (SES). The objective of this study was to assess calcium intake and source in older black women (n=33) and white women (n=33), matched in age and SES. Calcium intake and source were evaluated by interview using a 46-item calcium food frequency questionnaire including all food groups and supplements. Black and white women were identical in SES and matched on age (black women 66.9+/-6.2 years vs white women 67.1+/-5.5 years [mean+/-standard deviation], P=0.85). No significant difference existed for dietary calcium intake between black and white women (974+/-524 vs 1,070+/-600 mg/day; P=0.65) or total calcium intake between black and white women (1,485+/-979 vs 1,791+/-887 mg/day; P=0.15). Dairy foods contributed most to dietary calcium intake in black and white women and differed by race (black women 402+/-269 mg/day, white women, 603+/-376 mg/day; P=0.02). Calcium intake from grains differed by race (black women 205+/-201 mg/day vs white women 130+/-234 mg/day; P=0.010) and fortified cereals were a major source of calcium for black women. Calcium supplementation contributed substantially to total calcium intake in both groups, with more white women (n=23, 70%) using supplements than black women did (n=19, 58%). However, no racial difference existed in supplemented calcium intake (black women, n=19; 889+/-605 vs white women, n=23; 1,034+/-460 mg/day; P=0.20). Our data suggest that total daily dietary and supplemental calcium intakes do not differ, but calcium intake from dairy foods and from grains differ in older black and white women matched in age and SES.