Vitamin C and zinc intakes are related to bone macroarchitectural structure and strength in prepubescent girls.

The extent to which nutrient intake may influence bone structure and strength during maximal rates of skeletal growth remains uncertain. We examined the relationship of dietary intake of micronutrients and bone macroarchitectural structure in young girls. This cross-sectional analysis included baseline data from 363 fourth- and sixth-grade girls enrolled in the Jump-In study. Nutrient intake was assessed using the Harvard Youth/Adolescent Food Frequency Questionnaire. Volumetric BMD (vBMD), bone geometry, and strength were measured by peripheral quantitative computed tomography. Correlations and regression modeling assessed relations between usual nutrient intake and bone parameters. In fourth-grade girls, metaphyseal and diaphyseal area and circumferences as well as diaphyseal strength were associated with vitamin C intake (r = 0.15-0.19, p < 0.05). Zinc intake was correlated with diaphyseal vBMD (r = 0.15-0.16, p < 0.05). Using multiple linear regression to adjust for important covariates, we observed significant independent associations for vitamin C and zinc with bone parameters. For every milligram per day of vitamin C intake trabecular area increased by 11 %, cortical strength improved by 14 %, and periosteal and endosteal circumferences increased by 5 and 8.6 %, respectively. For every milligram per day of zinc intake, cortical vBMD increased by <1 %. No significant associations were observed in sixth-grade girls. Results of this study suggests that vitamin C and zinc intake are positively associated with objective measures of bone geometry, size, and strength in fourth-grade girls. This indicates that potential differences in micronutrient and bone associations at various age-associated stages of bone maturation may be indicative of competing hormonal influences.

Comparison between dietary assessment methods for determining associations between nutrient intakes and bone mineral density in postmenopausal women.

It is important to identify the role of nutrition in the treatment and prevention of osteoporosis. The goal of this study was to compare the equivalency of nutrient intakes assessed by diet records and the Arizona Food Frequency Questionnaire and the associations of these nutrients with bone mineral density (BMD). This is a secondary analysis of cross-sectional data that was analyzed from six cohorts (fall 1995 to fall 1997) of postmenopausal women (n=244; 55.7+/-4.6 years) participating in a 12-month, block-randomized, clinical trial. One-year dietary intakes were assessed using 8 days of diet records and the Arizona Food Frequency Questionnaire. Participants' BMD was measured at the lumbar spine (L2-L4), femur trochanter, femur neck, Ward's triangle, and total body using dual-energy x-ray absorptiometry. Linear regression analyses (P< or =0.05) were adjusted for the effects of exercise, hormone therapy use, body weight at 1 year, years post menopause, and total energy intake. Significant correlations (r=0.30 to 0.70, P< or =0.05) between dietary assessment methods were found with all dietary intake variables. Iron and magnesium were consistently and significantly positively associated with BMD at all bone sites regardless of the dietary assessment method. Zinc, dietary calcium, phosphorous, potassium, total calcium, and fiber intakes were positively associated with BMD at three or more of the same bone sites regardless of the dietary assessment method. Protein, alcohol, caffeine, sodium, and vitamin E did not have any similar BMD associations. Diet records and the Arizona Food Frequency Questionnaire are acceptable dietary tools used to determine the associations of particular nutrients and BMD sites in healthy postmenopausal women.

Maintenance of weight loss in overweight middle-aged women through the Internet.

OBJECTIVE: The purpose of this study was to compare weight regain in a group of perimenopausal women (48.0+/-4.4 years old), randomized to a 12-month weight maintenance Internet intervention or to self-directed weight maintenance after a 4-month weight loss treatment. METHODS AND PROCEDURES: After a 4-month behavioral weight loss program, 135 women were randomized to either Internet or self-directed groups. The Internet group (n=66) used a website to gain information and complete logs concerning their weight, diet, and exercise progress over a 12-month follow-up. The 69 self-directed women had no contact with study staff. All women were measured for weight and body composition, and diet intake, and were interviewed using the 7-day physical activity questionnaires at baseline, 4 months, and 16 months. RESULTS: At the end of the 12-month follow-up, the Internet and self-directed groups had regained on average 0.4+/-5.0 kg and 0.6+/-4.0 kg, respectively (P=0.5). In within-group analyses, Internet diet-log entries were correlated with follow-up weight change (r=-0.29; P<0.05) and moderately with change in exercise energy expenditure (EEE; r=0.44; P<0.01). Follow-up weight change was not correlated with change in dietary intake. DISCUSSION: While significant weight loss was maintained over follow-up by both groups of women, Internet use did not surpass self-direction in helping to sustain weight loss. Among Internet users, Internet use was related to weight change and EEE.

Psychosocial and behavioral profile and predictors of self-reported energy underreporting in obese middle-aged women.

Energy underreporting is a concern with dietary intake data; therefore, subject characteristics associated with underreporting energy intake should be elucidated. Baseline self-reported dietary intake and measures of diet and weight history, life status, weight-loss readiness, psychology, eating behavior, physical activity, and self-image of obese middle-aged women (mean body mass index [calculated as kg/m(2)]=31.0) enrolled in a lifestyle weight-loss program were evaluated. Of the 155 participating, 71 women were identified as underreporting energy intake using the Goldberg cutoff values. Comparison of means between psychosocial and behavioral measures from energy underreporters and energy accurate reporters were used to help develop logistic regression models that could predict likelihood to underreport energy intake based on baseline measures. Characteristics most predictive of energy underreporting included fewer years of education (P=0.01), less-realistic weight-loss goals (P=0.02), higher perceived exercise competence (P=0.07), more social support to exercise (P=0.04), more body-shape concern (P=0.01), and higher perception of physical condition (P=0.03). These results highlight distinct psychosocial and behavioral characteristics that, at baseline, can help identify the likelihood an overweight middle-aged woman entering a weight-loss intervention will underreport energy intake. These results can help provide a framework for screening study participants for probability of energy underreporting, based on baseline psychosocial and behavioral measures. This knowledge can help researchers target at-risk subjects and, through education and training, improve the accuracy of self-reported energy intake and, ultimately, the accuracy of energy and nutrient intake relationships with health and disease.

The psychosocial and behavioral characteristics related to energy misreporting.

Energy underreporting occurs in 2% to 85% and overreporting in 1% to 39% of various populations. Efforts are needed to understand the psychosocial and behavioral characteristics associated with misreporting to help improve the accuracy of dietary self-reporting. Past research suggests that higher social desirability and greater eating restraint are key factors influencing misreporting, while a history of dieting and being overweight are more moderately associated. Eating disinhibition, body image, depression, anxiety, and fear of negative evaluation may be related to energy misreporting, but evidence is insufficient. This review will provide a detailed discussion of the published associations among psychosocial and behavioral characteristics and energy misreporting.

Exercise motivation, eating, and body image variables as predictors of weight control.

PURPOSE: This study investigated changes in psychosocial variables related to exercise, eating, and body image during a weight reduction program and evaluated their association with weight loss in middle-aged overweight and obese women up to 1 yr after intervention. METHODS: The 136 participants (age, 48.1 +/- 4.4 yr; weight, 30.6 +/- 5.6 kg x m(-2)) who completed the 4-month lifestyle weight reduction program (86% retention), losing -6.2 +/- 4.6% (P < 0.001) of their initial weight, were followed up for 12 additional months. Of these, 82% completed 16-month assessments (weight change, -5.5 +/- 7.7%, P < 0.001). Psychosocial variables were assessed by validated instruments in standardized conditions at baseline and after the intervention (4 months). RESULTS: Compared with 4-month assessments, body weight did not change at 16 months (P > 0.09). Changes in eating restraint, disinhibition, and hunger; exercise, self-efficacy, and intrinsic motivation; body shape concerns; and physical self-worth were associated with weight change at 4 months (P < 0.001, except hunger, P < 0.05). Baseline-adjusted 4-month scores in all psychosocial variables also predicted weight change from baseline to 16 months (P < 0.01), except hunger (P > 0.05). After controlling for 4-month weight change and other covariates, increases in exercise intrinsic motivation remained predictive of weight loss at 16 months (P < 0.05). Multiple linear regression showed that eating variables were significant and independent correlates of short-term weight change, whereas changes in exercise variables were stronger predictors of longer term weight outcomes. CONCLUSIONS: Results highlight the importance of cognitive processes during weight control and support the notion that initial focus on diet is associated with short-term weight loss, while change in exercise-related motivational factors, with a special emphasis on intrinsic sources of motivation (e.g., interest and enjoyment in exercise), play a more important role in longer term weight management.

Exercise frequency and calcium intake predict 4-year bone changes in postmenopausal women.

The aim of this study was to examine the association of exercise frequency and calcium intake (CI) with change in regional and total bone mineral density (BMD) in a group of postmenopausal women completing 4 years of progressive strength training. One hundred sixty-seven calcium-supplemented (800 mg/day) sedentary women (56.1+/-4.5 years) randomized to a progressive strength training exercise program or to control were followed for 4 years. Fifty-four percent of the women were using hormone therapy (HT) at baseline. At 1 year, controls were permitted to begin the exercise program (crossovers). The final sample included 23 controls, 55 crossovers, and 89 randomized exercisers. Exercisers were instructed to complete two sets of six to eight repetitions of exercises at 70-80% of one repetition maximum, three times weekly. BMD was measured at baseline and thereafter annually using dual-energy X-ray absorptiometry. Four-year percentage exercise frequency (ExFreq) averaged 26.8%+/-20.1% for crossovers (including the first year at 0%), and 50.4%+/-26.7% for exercisers. Four-year total CI averaged 1,635+/-367 mg/day and supplemental calcium intake, 711+/-174 mg/day. In adjusted multiple linear regression models, ExFreq was positively and significantly related to changes in femur trochanter (FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. Among HT users, FT BMD increased 1.5%, and FN and LS BMD, 1.2% (p<0.01) for each standard deviation (SD) of percentage ExFreq (29.5% or 0.9 days/week). HT non-users gained 1.9% and 2.3% BMD at FT and FN, respectively, (p<0.05) for every SD of CI. The significant, positive, association between BMD change and ExFreq supports the long-term usefulness of strength training exercise for the prevention of osteoporosis in postmenopausal women, especially HT users. The positive relationship of CI to change in BMD among postmenopausal women not using HT has clinical implications in light of recent evidence of an increased health risk associated with HT.

Dietary iron positively influences bone mineral density in postmenopausal women on hormone replacement therapy.

The associations of dietary intakes of iron and calcium on change in bone mineral density (BMD) were examined over 1 y in healthy nonsmoking postmenopausal women (mean age 55.6 +/- 4.6 y) stratified by hormone replacement therapy (HRT) use (HRT, n = 116; no HRT, n = 112). BMD was measured at lumbar spine L(2)-L(4), trochanter, femur neck, Ward's triangle, and total body using dual-energy X-ray absorptiometry at baseline and 1 y. Mean nutrient intakes were assessed using 8-d diet records. All women received 800 mg/d of supplemental elemental calcium. Regression analyses examined the effects of iron and calcium intakes on BMD change adjusting for years past menopause, baseline BMD, weight change, exercise, and energy intake. The interaction of iron with calcium on BMD change was assessed using tertiles of iron and calcium intake and estimated marginal mean change in BMD. Iron was associated (P < or = 0.05) with greater positive BMD change at the trochanter and Ward's triangle in women using HRT. Calcium was associated (P < or = 0.05) with BMD change at the trochanter and femur neck for women not using HRT. In women using HRT in the lowest tertile of calcium intake, change in femur neck BMD increased linearly as iron intake increased. In women not using HRT, BMD increased in the women in the highest tertile of calcium intake. We conclude that HRT use appears to influence the associations of iron and calcium on change in BMD.

Dietary iron is associated with bone mineral density in healthy postmenopausal women.

Healthy nonsmoking postmenopausal women (n = 242; ages 40-66 y) were included in the Bone, Estrogen, and Strength Training (BEST) Study. Bone mineral density (BMD) was measured at five sites (lumbar spine L2-L4, trochanter, femur neck, Ward's triangle and total body) using dual energy X-ray absorptiometry (DXA). Mean nutrient intakes were assessed using a 3-d diet record. Regression models were calculated using each BMD site as the dependent variable and iron as the independent variable. Covariates included in the models were years past menopause, fat-free mass, fat mass, use of hormone replacement therapy, total energy intake and dietary intake of protein and calcium. Using linear models, iron was associated with greater BMD at all sites (P < or = 0.01), even after adjusting for protein and/or calcium. Increasing levels of iron intake (>20 mg) were associated with greater BMD at several bone sites among women with a mean calcium intake of 800-1200 mg/d. Elevated iron intake was not associated with greater BMD among women with higher (>1200 mg/d) or lower calcium intakes (<800 mg/d). Dietary iron may be a more important factor in bone mineralization than originally thought and, its combined effect with calcium on BMD warrants exploration in future studies.

Resistance training in postmenopausal women with and without hormone therapy.

PURPOSE: The main purpose of this study was to analyze the impact of a 1-yr resistance-training program on body composition and muscle strength in postmenopausal women, and to describe the impact of hormone replacement therapy (HRT) on body composition changes, with and without exercise. Secondarily, we wanted to study dose-response relationships between measures of program compliance and changes in primary outcomes. METHODS: Subjects were postmenopausal women (40-66 yr) randomly assigned to an exercise (EX) group (N = 117) and a nonexercise group (N = 116). The EX group participated in a 1 yr trainer-supervised resistance-training program, 60-75 min.d-1, 3 d.wk-1. Lean soft tissue (LST) and fat tissue (FT) changes were measured by dual-energy x-ray absorptiometry and strength by one-repetition maximum testing. RESULTS: Significant (P < 0.001) gains in LST were observed for women who exercised, regardless of HRT status, whereas women who did not exercise lost LST (P < 0.05) if they were not taking HRT, and gained LST (P = 0.08) if they were on HRT. The only significant FT losses were observed for women who exercised while on HRT (P < 0.05). Strength increases were observed at all sites (P < 0.001). Total weight lifted by subjects in their training sessions was a significant predictor of changes in LST (P < 0.001) and strength (P < 0.01). CONCLUSIONS: Resistance and weight-bearing exercise significantly changed total and regional body composition in postmenopausal women by increasing LST in all women and decreasing FT in women on HRT. Hormone therapy showed no independent effects on body composition, but it protected nonexercising women from losses in LST. The lean and muscle strength changes observed were partially dependent on the volume of training, as expressed by attendance and total weight lifted in 1 yr of training.

Weight lifted in strength training predicts bone change in postmenopausal women.

PURPOSE: The aim of this study was to examine the relationship between weight lifted in 1 yr of progressive strength training and change in bone mineral density (BMD) in a group of calcium-replete, postmenopausal women. METHODS: As part of a large clinical trial, 140 calcium-supplemented women, 44-66 yr old, were randomized to a 1-yr progressive strength-training program. Half of the women were using hormone replacement therapy. Three times weekly, subjects completed two sets of six to eight repetitions in eight core exercises at 70-80% of one repetition maximum. BMD was measured at baseline and 1 yr. RESULTS: In multiple linear regression, the increase in femur trochanter (FT) BMD was positively related to total weight lifted (0.001 g.cm (-2)) for a SD of weight lifted, P< 0.01) after adjusting for age, baseline factors, HRT status, weight change, cohort, and fitness center. The weighted squats showed the strongest (0.002 g.cm(-2)) for a SD of weight lifted, P< 0.001), whereas the back extension exhibited the weakest (0.0005 g.cm(-2)) for a SD of weight lifted, P< 0.26) association with change in FT BMD. The amount of weight lifted in the weighted march exercise was significantly related to total body BMD (0.0006 g.cm(-2)) for a SD of weight lifted, P< 0.01). The associations between weight lifted and BMD for the femur neck or lumbar spine were not significant. CONCLUSION: Evidence of a linear relationship between BMD change and total and exercise-specific weight lifted in a 1-yr strength-training program reinforces the positive association between this type of exercise and BMD in postmenopausal women.

Weight loss readiness in middle-aged women: psychosocial predictors of success for behavioral weight reduction.

Accurate prediction of weight loss success and failure has eluded researchers for many years. Thus, we administered a comprehensive psychometric battery before a 4-month lifestyle behavioral weight reduction program and analyzed weight changes during that period to identify baseline characteristics of successful and unsuccessful participants, among 112 overweight and obese middle-aged women (age, 47.8 +/- 4.4 years; BMI, 31.4 +/- 3.9 kg/m2). Mean weight and percentage fat losses among the 89 completers were -5.4 kg and -3.4%, respectively (p < .001). A higher number of recent dieting attempts and recent weight loss, more stringent weight outcome evaluations, a higher perceived negative impact of weight on quality of life, lower self-motivation, higher body size dissatisfaction, and lower self-esteem were associated with less weight loss and significantly distinguished responders from nonresponders among all participants. These findings are discussed as to their usefulness (i) to screen individuals before treatment, (ii) to provide a better match between interventions to participants, and (iii) to build a weight loss readiness questionnaire.

Assessing the validity of body mass index standards in early postmenopausal women.

OBJECTIVE: To examine the relationship between percentage of total body fat (%Fat) and body mass index (BMI) in early postmenopausal women and to evaluate the validity of the BMI standards for obesity established by the NIH. RESEARCH METHODS AND PROCEDURES: Three hundred seventeen healthy, sedentary, postmenopausal women (ages, 40 to 66 years; BMI, 18 to 35 kg/m(2); 3 to 10 years postmenopausal) participated in the study. Height, weight, BMI, and %Fat, as assessed by DXA, were measured. Receiver operating characteristic analysis was performed to evaluate the ability of BMI to discriminate obesity from non-obesity using 38%Fat as the criterion value. RESULTS: A moderately high relationship was observed between BMI and %Fat (r = 0.81; y = 1.41x + 2.65) with a SE of estimate of 3.9%. Eighty-one percent of other studies examined fell within 1 SE of estimate as derived from our study. Receiver operating characteristic analysis showed that BMI is a good diagnostic test for obesity. The cutoff for BMI corresponding to the criterion value of 38%Fat that maximized the sum of the sensitivity and specificity was 24.9 kg/m(2). The true-positive (sensitivity) and false-positive (1--specificity) rates were 84.4% and 14.6%, respectively. The area under the curve estimate for BMI was 0.914. DISCUSSION: There is a strong association between %Fat and BMI in postmenopausal women. Current NIH BMI-based classifications for obesity may be misleading based on currently proposed %Fat standards. BMI >25 kg/m(2) rather than BMI >30 kg/m(2) may be superior for diagnosing obesity in postmenopausal women.