Bone minerals changes in obese women during a moderate weight loss with and without calcium supplementation

Comparison of three weight maintenance programs on cardiovascular risk, bone and vitamins in sedentary older adults

OBJECTIVE

Obese patients with knee osteoarthritis (OA) are encouraged to lose weight to obtain symptomatic relief. Risk of vascular events is higher in people with OA compared to people without arthritis. Our aim in this randomized trial was to compare changes in cardiovascular disease (CVD) risk-factors, nutritional health, and body composition after 1-year weight-loss maintenance achieved by [D]diet, [E]knee-exercise, or [C]control, following weight loss by low-energy-diet.

DESIGN AND METHODS

Obese individuals (n = 192, >50 years) with knee OA, 63 years (SD 6), weight 103.2 kg (15.0), body-mass index 37.3 kg/m(2) (4.8), were enrolled into a 68-week weight-loss trial.

RESULTS

Mean changes in weight, in D, E, and C were -11.0, -6.3, and -8.3 kg (P = 0.002). Reduction in waist circumference in D, E, and C were -8.4, -4.6, and -7.0 cm (P = 0.007). D reduced waist circumference significantly more than E: -3.8 cm (95%CI -6.2 to -1.4; P = 0.0024). There was no difference between the groups in changes in CVD risk factors; blood pressure, triglycerides, and cholesterol. Nutritional health was improved in all groups. For markers of bone, no statistical difference was found between the groups.

CONCLUSIONS

Dietary support, or control, maintained improvements in cardiovascular risk factors to the same extent and none of the interventions had a detrimental effect on bone.

Skeletal alterations in women affected by obesity

Obesity has always been considered a protective factor for the skeleton and for osteoporosis. However, new epidemiologic and clinical data have shown that high level of fat mass might be a risk factor for osteoporosis and fragility fractures. Further, increasing evidences seem to indicate that the different components of metabolic syndrome (i.e. hypertension, increased triglycerides, and reduced high-density lipoprotein cholesterol) are also potential risk factors for the development of low bone mineral density and osteoporosis.

Negative association between trunk fat, insulin resistance and skeleton in obese women

AIM

To evaluate the potential interference of trunk fat (TF) mass on metabolic and skeletal metabolism.

METHODS

In this cross-sectional study, 340 obese women (mean age: 44.8 ± 14 years; body mass index: 36.0 ± 5.9 kg/m(2)) were included. Patients were evaluated for serum vitamin D, osteocalcin (OSCA), inflammatory markers, lipids, glucose and insulin (homeostasis model assessment of insulin resistance, HOMA-IR) levels, and hormones profile. Moreover, all patients underwent measurements of bone mineral density (BMD; at lumbar and hip site) and body composition (lean mass, total and trunk fat mass) by dual-energy X-ray absorptiometry.

RESULTS

Data showed that: (1) high TF mass was inversely correlated with low BMD both at lumbar (P < 0.001) and hip (P < 0.01) sites and with serum vitamin D (P < 0.0005), OSCA (P < 0.0001) and insulin-like growth factor-1 (IGF-1; P < 0.0001) levels; (2) a positive correlation was found between TF and HOMA-IR (P < 0.01), fibrinogen (P < 0.0001) and erythrocyte sedimentation rate (P < 0.0001); (3) vitamin D levels were directly correlated with IGF-1 (P < 0.0005), lumbar (P < 0.006) and hip (P < 0.01) BMD; and (4) inversely with HOMA-IR (P < 0.001) and fibrinogen (P < 0.0005).Multivariate analysis demonstrated that only vitamin D was independent of TF variable.

CONCLUSION

In obese women, TF negatively correlates with BMD independently from vitamin D levels. Reduced IGF-1 and increased inflammatory markers might be some important determinants that account for this relationship.

Combined aerobic and resistance exercise is effective for achieving weight loss and reducing cardiovascular risk factors without deteriorating bone health in obese young adults

PURPOSE

Weight loss reduces cardiovascular risk factors in the obese. However, weight reduction through diet negatively affects long-term bone health. The aim of study was to determine the ability of combined aerobic and resistance exercise (CE) to reduce weight and cardiovascular risk without diminishing bone health.

METHODS

Twenty-five young adults participated in an 8-week weight loss CE program. Subjects were allocated to an obese group or a control group by body mass index (BMI). Body weight, BMI, body composition, and bone mineral density (BMD) of the lumbar spine and total hip were measured before and after the CE trial. Serum levels of metabolic markers, including adipokines and bone markers, were also evaluated.

RESULTS

Weight loss was evident in the obese group after the 8 weeks CE trial. Fat mass was significantly reduced in both groups. Fasting insulin, homeostatic model assessment-insulin resistance (HOMA-IR), leptin and aminotransferases level were significantly reduced from baseline only in the obese group. High density lipoprotein cholesterol increased in both groups. Hip BMD increased in the obese group. In all study subjects, BMI changes were correlated with HOMA-IR, leptin, and HDL changes. BMI decreases were correlated with lumbar spine BMD increases, lumbar spine BMD increases were positively correlated with osteocalcin changes, and lumbar spine bone mineral content increases were correlated negatively with C-terminal telopeptide of type 1 collagen changes.

CONCLUSION

These findings suggest that CE provides effective weight loss and improves cardiovascular risk factors without diminishing BMD. Furthermore, they indicate that lumbar spine BMD might be maintained by increasing bone formation and decreasing bone resorption.

The effects of weight loss on relative bone mineral density in premenopausal women

OBJECTIVE

This study compared BMD relative to body weight following a ∼6-month weight loss program and a 1-year weight maintenance phase in premenopausal women and determined whether African American (AA) and European-American (EA) women's BMD respond similarly during weight loss.

DESIGN AND METHODS

Premenopausal women (n = 115, 34 ± 5 years) were evaluated in an overweight state (BMI between 27 and 30 kg/m(2) ), following an 800 kcal/day diet/exercise program designed to reduce BMI<25 kg/m(2) , and 1-year following weight loss.

RESULTS

BMD relative to body weight (Z-scores) increased after weight loss, but decreased during the 1-year weight maintenance phase. All 1-year follow-up BMD Z-scores were increased (except L1) compared to baseline measurements (P < 0.05). These sites included the hip neck (+0.088, P = 0.014), total hip (+0.099, P = 0.001), L2 (+0.127, P = 0.013), L3 (+0.135, P = 0.014), and L4 (+0.199, P = 0.002). AAs had significantly higher absolute BMD at all sites (P < 0.05) compared to EAs, but no time by race interactions were evident during weight loss (except in L3).

CONCLUSION

These results may indicate that weight loss is safe with regard to bone health for overweight premenopausal women.

25-Hydroxyvitamin D Supplementation and BMI Change: A Meta-Analysis of Randomized Controlled Trials

The impact of 25-hydroxyvitamin D (25[OH]D) supplementation on weight change remains controversial. The objective of this study was to summarize the effects of 25[OH]D supplementation (cholecalciferol or ergocalciferol) on BMI change through a meta-analysis of published clinical trials. We completed a systematic review of English articles, using MEDLINE (Ovid, Pubmed) from January 1, 1998 through January 1, 2013. The articles selected focused on 25[OH]D supplementation and body mass index (BMI) in randomized controlled trials (RCT’s). The association between 25[OH]D and mean BMI change was estimated utilizing a random effects model. A total of 30 studies were reviewed and 9 were included in the meta-analysis. Total participants included 1651 adults (82.6% women and mean age 47.9 years) and mean follow-up ranged between 6 to 196 weeks and mean daily 25[OH]D dose ranged from 200 IU to 1,110 IU. Five of the 9 studies included calcium supplementation in both groups. Average baseline BMI was 30.7 and 30.4 kg/m² in the intervention and control groups, respectively. Five studies suggested a beneficial effect for 25[OH]D supplementation for BMI change whereas 3 studies showed no effect of 25[OH]D supplementation on BMI change, and one showed a non-perceptible change. Meta-analysis of BMI values at end of trial showed no statistically significant difference in BMI change by use of 25[OH]D supplementation. Based on existing published trials, oral 25[OH]D supplementation does not significantly impact BMI change.

Bariatric surgery, bone loss, obesity and possible mechanisms

Bariatric surgery remains the most effective treatment for severely obese patients. However, the potential long-term effects of bariatric surgical procedures on health, including bone health, are only partially understood. The goal of this review was to present data on the impact of bariatric surgery on bone metabolism and to analyse possible reasons for the loss of bone mass that frequently occurs after bariatric surgery. Such factors include nutritional deficiencies, rapid weight loss per se, effects of fat-derived adipokines and gut-derived appetite-regulatory hormones. However, the relative roles of these factors in skeletal regulation and the mechanisms by which they work are not yet fully defined. Our review was focussed on the complex relationship between body weight, fat mass and bone mass, as well as peripheral and central mediators potentially involved in the dual regulation of both energy and bone homeostasis. We also review the data on the inverse relationship between central obesity, bone marrow fat and osteoporosis. As the number of bariatric operations increases, it is imperative to recognize mechanisms responsible for bariatric surgery-induced bone loss, with careful monitoring of bone health including long-term fracture incidence in patients undergoing these procedures.

Bone metabolism in obesity and weight loss

Excess body weight due to obesity has traditionally been considered to have a positive effect on bone; however, more recent findings suggest that bone quality is compromised. Both obesity and caloric restriction increase fracture risk and are regulated by endocrine factors and cytokines that have direct and indirect effects on bone and calcium absorption. Weight reduction will decrease bone mass and mineral density, but this varies by the individual's age, gender, and adiposity. Dietary modifications, exercise, and medications have been shown to attenuate the bone loss associated with weight reduction. Future obesity and weight loss trials would benefit from assessment of key hormones, adipokine and gut peptides that regulate calcium absorption, and bone mineral density and quality by using sensitive techniques in high-risk populations.

Weight loss is associated with increased serum 25-hydroxyvitamin D in overweight or obese women

Low circulating concentrations of vitamin D metabolites have been associated with increased risk for several diseases and clinical conditions. Large observational studies and surveys have shown that obesity is independently associated with lower serum 25-hydroxyvitamin D (25(OH)D) concentration. Few studies have examined the effect of weight loss on serum 25(OH)D concentration. The purpose of this study was to prospectively examine the effect of weight loss on serum 25(OH)D concentration. Data were collected from 383 overweight or obese women who participated in a 2-year clinical trial of a weight-loss program, in which 51% (N = 195) lost at least 5% of baseline weight by 24 months, 18% (N = 67) lost 5-10%, and 33% (N = 128) lost >10%. Women who did not lose weight at 24 months had an increase in serum 25(OH)D of 1.9 (9.7) ng/ml (mean (SD)); 25(OH)D increased by 2.7 (9.1) ng/ml for those who lost 5-10% of baseline weight; and 25(OH)D increased by 5.0 (9.2) ng/ml for those who lost >10% of baseline weight (P = 0.014). At baseline, 51% (N = 197) of participants met or exceeded the recommended serum concentration of 20 ng/ml. By study end, 64% (N = 230) of overweight or obese women met this goal, as well as 83% (N = 20) of those whose weight loss achieved a normal BMI. These findings suggest that weight loss, presumably associated with a reduction in body fat, is associated with increased serum 25(OH)D concentration in overweight or obese women.

Obesity in Older Adults: Technical Review and Position Statement of the American Society for Nutrition and NAASO, The Obesity Society

Obesity causes serious medical complications and impairs quality of life. Moreover, in older persons, obesity can exacerbate the age-related decline in physical function and lead to frailty. However, appropriate treatment for obesity in older persons is controversial because of the reduction in relative health risks associated with increasing body mass index and the concern that weight loss could have potential harmful effects in the older population. This joint position statement from the American Society for Nutrition and NAASO, The Obesity Society reviews the clinical issues related to obesity in older persons and provides health professionals with appropriate weight-management guidelines for obese older patients. The current data show that weight-loss therapy improves physical function, quality of life, and the medical complications associated with obesity in older persons. Therefore, weight-loss therapy that minimizes muscle and bone losses is recommended for older persons who are obese and who have functional impairments or medical complications that can benefit from weight loss.

The inclusion of a partial meal replacement with or without inulin to a calorie restricted diet contributes to reach recommended intakes of micronutrients and decrease plasma triglycerides: a randomized clinical trial in obese Mexican women

Background

Obesity is a major public health problem in many poor countries where micronutrient deficiencies are prevalent. A partial meal replacement may be an effective strategy to decrease obesity and increase micronutrient intake in such populations. The objective was to evaluate the efficacy of a partial meal replacement with and without inulin on weight reduction, blood lipids and micronutrients intake in obese Mexican women.

Methods

In a randomized controlled clinical trial 144 women (18–50 y) with BMI ≥ 25 kg/m², were allocated into one of the following treatments during 3 months: 1) Two doses/d of a partial meal replacement (PMR), 2) Two doses/d of PMR with inulin (PMR + I) , 3) Two doses/d of 5 g of inulin (INU) and 4) Control group (CON). All groups received a low calorie diet (LCD). Weight, height, hip and waist circumference were measured every 2 weeks and body composition, lipids and glucose concentration and nutrient intake were assessed at baseline and after 3 months.

Results

All groups significantly reduced weight, BMI, waist and hip circumference. Differences between groups were only observed in BMI and weight adjusted changes: At 45 days PMR group lost more weight than INU and CON groups by 0.9 and 1.2Kg, respectively. At 60 days, PMR + I and PMR groups lost more weight than in INU by 0.7 and 1Kg, respectively. Subjects in PMR, PMR + I and INU significantly decreased triglycerides. Energy intake was reduced in all groups. Fiber intake increased in PMR + I and INU groups. Some minerals and vitamins intakes were higher in PMR and PMR + I compared with INU and CON groups.

Conclusion

Inclusion of PMR with and without inulin to a LCD had no additional effect on weight reduction than a LCD alone but reduced triglycerides and improved intake of micronutrients during caloric restriction. PMR could be a good alternative for obese populations with micronutrient deficiencies.

ClinicalTrials.Gov ID

NCT01505023

Weight loss in obese older adults increases serum sclerostin and impairs hip geometry but both are prevented by exercise training

We reported that weight loss induces bone loss which is prevented by exercise training; however, the mechanism for this observation remains unclear. Sclerostin, an inhibitor of bone formation, has been found to increase in states of unloading and may mediate the changes in bone metabolism associated with weight loss and exercise. The objective of the study was to determine the effect of lifestyle intervention in obese older adults on sclerostin levels, and on hip geometry parameters. A total of 107 obese (body mass index [BMI] ≥ 30 kg/m(2)) older (≥65 years) adults were randomly assigned to control, diet, exercise, and combined diet-exercise for 1 year. Sclerostin levels were measured by ELISA at baseline, 6 months, and 12 months, while hip geometry parameters were obtained from bone mineral density (BMD) images done by dual-energy X-ray absorptiometry using hip structure analysis at baseline and 12 months. Both the diet and diet-exercise groups had significant decreases in body weight (-9.6% and -9.4%, respectively), whereas weight was stable in the exercise and control groups. Sclerostin levels increased significantly and progressively in the diet group (6.6% ± 1.7% and 10.5% ± 1.9% at 6 and 12 months, respectively, all p < 0.05), whereas they were unchanged in the other groups; in particular, they were stable in the diet-exercise group (0.7% ± 1.6% and 0.4% ± 1.7% at 6 and 12 months, respectively, all p = 0.05). Hip geometry parameters showed significant decreases in cross-sectional area, cortical thickness, and BMD; and increases in buckling ratio at the narrow neck, intertrochanter, and femoral shaft. These negative changes on bone geometry were not observed in the diet-exercise group. Significant correlations between changes in sclerostin and changes in certain hip geometry parameters were also observed (p < 0.05). In conclusion, the increase in sclerostin levels with weight loss that was prevented by exercise may partly mediate the negative effects of weight loss on bone metabolism and the osteoprotective effect of exercise training.

Beneficial impact of aerobic exercises on bone mineral density in obese premenopausal women under caloric restriction

OBJECTIVE

The aim of this study was to assess the impact of caloric restriction diet versus caloric restriction diet combined with aerobic exercises on bone mineral density (BMD) in obese premenopausal women.

SUBJECTS AND METHODS

Forty premenopausal obese women were classified randomly into two groups equal in number. The first group (group A) received caloric restriction diet, while the second (group B) received caloric restriction diet combined with a program of aerobic exercises, over 3 months. The variables measured in this study included age, weight, height, body mass index, fat weight, lean mass, fat percent, basal metabolic rate, and BMD.

RESULTS

The comparison between group A and group B showed significantly higher post-treatment lean mass, basal metabolic rate, and BMD in weight-bearing bones (L2-L4 lumbar spine and total hip) in group B compared to group A. In contrast to the BMD of the weight-bearing bones, the BMD of the radius showed significant decrease between the pre- and post-treatment results in groups A and B with no significant differences between the two groups.

CONCLUSION

A greater improvement in the BMD of weight-bearing bones was observed in obese premenopausal women undergoing caloric restriction combined with exercise than in those not undergoing exercise. Anaerobic exercises incorporated into weight loss programs help offset the adverse effects of dietary restriction on bone.

Improved nutritional status and bone health after diet-induced weight loss in sedentary osteoarthritis patients: a prospective cohort study

BACKGROUND/OBJECTIVES:

Obese subjects are commonly deficient in several micronutrients. Weight loss, although beneficial, may also lead to adverse changes in micronutrient status and body composition. The objective of the study is to assess changes in micronutrient status and body composition in obese individuals after a dietary weight loss program.

SUBJECTS/METHODS:

As part of a dietary weight loss trial, enrolling 192 obese patients (body mass index >30 kg/m²) with knee osteoarthritis (>50 years of age), vitamin D, ferritin, vitamin B₁₂ and body composition were measured at baseline and after 16 weeks. All followed an 8-week formula weight-loss diet 415–810 kcal per day, followed by 8 weeks on a hypo-energetic 1200 kcal per day diet with a combination of normal food and formula products. Statistical analyses were based on paired samples in the completer population.

RESULTS:

A total of 175 patients (142 women), 91%, completed the 16-week program and had a body weight loss of 14.0 kg (95% confidence interval: 13.3–14.7; P<0.0001), consisting of 1.8 kg (1.3–2.3; P<0.0001) lean body mass (LBM) and 11.0 kg (10.4–11.6; P<0.0001) fat mass. Bone mineral content (BMC) did not change (-13.5 g; P=0.18), whereas bone mineral density (BMD) increased by 0.004 g/cm² (0.001–0.008 g/cm²; P=0.025). Plasma vitamin D and B₁₂ increased by 15.3 nmol/l (13.2–17.3; P<0.0001) and 43.7 pmol/l (32.1–55.4; P<0.0001), respectively. There was no change in plasma ferritin.

CONCLUSIONS:

This intensive program with formula diet resulted in increased BMD and improved vitamin D and B₁₂ levels. Ferritin and BMC were unchanged and loss of LBM was only 13% of the total weight loss. This observational evidence supports use of formula diet-induced weight loss therapy in obese osteoarthritis patients.

Weight-loss-associated changes in bone mineral density and bone turnover after partial weight regain with or without aerobic exercise in obese women

Background/Objectives

Moderate, long-term weight loss results in loss of bone mass in overweight or obese premenopausal women. However, whether these changes persist during weight maintenance or regain remains to be determined.

Subjects/Methods

Overweight or obese (BMI: 25.8–42.5 kg/m²) women (n=40) with at least two risk factors for the metabolic syndrome participated in this 12-mo study that examined the effects of prescribed weight loss and regain, with or without exercise, on bone turnover and on bone mineral density (BMD) in a subset of participants (n=24). During the first 6 mo, participants lost ~10% of their initial body weight via energy restriction and supervised aerobic exercise. Following weight loss, participants were randomly assigned to either an exercise or a no-exercise treatment for the regain (+50% of weight lost) phase. A one-way (time) repeated measures ANOVA tested the effects of weight loss on BMD and bone turnover, and a two-way RM ANOVA (time, exercise) was used to examine the effects of exercise during weight regain.

Results

Hip (p=0.007) and lumbar spine (p=0.05) BMD decreased with weight loss, and remained reduced after weight regain with or without exercise. Likewise, the weight-loss-associated increases in osteocalcin (p<0.001) and C-terminal peptide of type I collagen (p<0.001) persisted following weight regain, independent of exercise.

Conclusions

the results of the present study, which is the first to examine changes in bone mass and turnover during carefully controlled weight regain, suggest that weight-loss-induced perturbations in bone mass and turnover persist after partial weight regain, regardless of whether regular, weight-bearing aerobic exercise was continued.

Dietary calcium but not elemental calcium from supplements is associated with body composition and obesity in Chinese women

Objective

We assessed whether dietary calcium intake or calcium supplements associated with body composition and obesity in a Chinese population.

Methods

A cross-sectional survey was performed in a population of 8940, aged 20 to 74 y. 8127 participants responded (90.9%). Height, weight, fat mass (FM), waist circumference (WC) and hip circumference were measured. Obesity definition: body mass index (BMI) ≥28 kg/m² (overall obesity); WC ≥85 cm for men or ≥80 cm for women (abdominal obesity І) and waist hip ratio (WHR) ≥0.90 for men or ≥0.85 for women (abdominal obesity П). The data on dietary calcium and calcium supplements were collected using food-frequency questionnaire and self-report questionnaire. Multivariate linear and multivariable logistic regressions were used to examine the associations between dietary calcium intake or calcium supplements and body composition and obesity.

Principal Findings

The average dietary calcium intake of all subjects was 430 mg/d. After adjusting for potential confounding factors, among women only, negative associations were observed between habitual dietary calcium intake and four measures of body composition (β, −0.086, P<0.001 for BMI; β, −0.072, P<0.001 for WC; β, −0.044, P<0.05 for WHR; and β, −0.058, P<0.01 for FM, respectively) and both measures of abdominal obesity (Odds Ratio [OR] = 0.86, 95% Confidence Interval [CI], 0.80–0.93; P<0.001, for abdominal obesity I; OR = 0.92, 95% CI, 0.86–0.99; P = 0.026, for abdominal obesity II). These associations were not observed among men (P>0.05). Similarly, among both men and women, we did not observe significant associations between calcium supplements and any measures of body composition or abdominal obesity (P>0.05).

Conclusions

Dietary calcium from food rather than elemental calcium from calcium supplements has beneficial effects on the maintenance of body composition and preventing abdominal obesity in Chinese women.

A losing battle: weight regain does not restore weight loss-induced bone loss in postmenopausal women

Previously, we reported significant bone mineral density (BMD) loss in postmenopausal women after modest weight loss. It remains unclear whether the magnitude of BMD change in response to weight loss is appropriate (i.e., proportional to weight loss) and whether BMD is recovered with weight regain. We now report changes in BMD after a 1-year follow-up. Subjects (n = 23) in this secondary analysis were postmenopausal women randomized to placebo as part of a larger trial. They completed a 6-month exercise-based weight loss program and returned for follow-up at 18 months. Dual-energy X-ray absorptiometry (DXA) was performed at baseline, 6, and 18 months. At baseline, subjects were aged 56.8 ± 5.4 years (mean ± s.d.), 10.0 ± 9.2 years postmenopausal, and BMI was 29.6 ± 4.0 kg/m(2). They lost 3.9 ± 3.5 kg during the weight loss intervention. During follow-up, they regained 2.9 ± 3.9 kg. Six months of weight loss resulted in a significant decrease in lumbar spine (LS) (-1.7 ± 3.5%; P = 0.002) and hip (-0.04 ± 3.5%; P = 0.03) BMD that was accompanied by an increase in a biomarker of bone resorption (serum C-terminal telopeptide of type I collagen, CTX: 34 ± 54%; P = 0.08). However, weight regain was not associated with LS (0.05 ± 3.8%; P = 0.15) or hip (-0.6 ± 3.0%; P = 0.81) bone regain or decreased bone resorption (CTX: -3 ± 37%; P = 0.73). The findings suggest that BMD lost during weight reduction may not be fully recovered with weight regain in hormone-deficient, postmenopausal women. Future studies are needed to identify effective strategies to prevent bone loss during periods of weight loss.

Exercise training in obese older adults prevents increase in bone turnover and attenuates decrease in hip bone mineral density induced by weight loss despite decline in bone-active hormones

Weight loss therapy to improve health in obese older adults is controversial because it causes further bone loss. Therefore, it is recommended that weight loss therapy should include an intervention such as exercise training (ET) to minimize bone loss. The purpose of this study was to determine the independent and combined effects of weight loss and ET on bone metabolism in relation to bone mineral density (BMD) in obese older adults. One-hundred-seven older (age >65 years) obese (body mass index [BMI] ≥ 30  kg/m(2) ) adults were randomly assigned to a control group, diet group, exercise group, and diet-exercise group for 1 year. Body weight decreased in the diet (-9.6%) and diet-exercise (-9.4%) groups, not in the exercise (-1%) and control (-0.2%) groups (between-group p  <  0.001). However, despite comparable weight loss, bone loss at the total hip was relatively less in the diet-exercise group (-1.1%) than in the diet group (-2.6%), whereas BMD increased in the exercise group (1.5%) (between-group p  <  0.001). Serum C-terminal telopeptide (CTX) and osteocalcin concentrations increased in the diet group (31% and 24%, respectively), whereas they decreased in the exercise group (-13% and -15%, respectively) (between-group p  <  0.001). In contrast, similar to the control group, serum CTX and osteocalcin concentrations did not change in the diet-exercise group. Serum procollagen propeptide concentrations decreased in the exercise group (-15%) compared with the diet group (9%) (p  =  0.04). Serum leptin and estradiol concentrations decreased in the diet (-25% and -15%, respectively) and diet-exercise (-38% and -13%, respectively) groups, not in the exercise and control groups (between-group p  =  0.001). Multivariate analyses revealed that changes in lean body mass (β  =  0.33), serum osteocalcin (β  = -0.24), and one-repetition maximum (1-RM) strength (β  =  0.23) were independent predictors of changes in hip BMD (all p  <  0.05). In conclusion, the addition of ET to weight loss therapy among obese older adults prevents weight loss-induced increase in bone turnover and attenuates weight loss-induced reduction in hip BMD despite weight loss-induced decrease in bone-active hormones.

An old friend in a new light: the role of osteocalcin in energy metabolism

Accumulating evidence suggests interactions between bone and energy metabolism, which may affect the risk of cardiovascular disease. Recent animal studies indicate that osteocalcin (OC) plays a key role in the coordinated regulation of glucose and insulin metabolism while insulin receptors on osteoblasts may regulate bone turnover and circulating OC levels. Association studies, weight loss interventions, and observational data lend some support to the existence and relevance of these mechanisms in humans. However, corroborating evidence from pharmacologic interventions in either bone or glucose metabolism is limited by the number, design, and complex pharmacological effects of the drugs used. Furthermore, such clinical trials are complicated by the alteration of metabolic feedback mechanisms in the insulin resistant state. Purpose-designed studies are needed to further establish the existence and significance of the role of OC and its subfractions in human insulin metabolism. In this review we summarize existing animal evidence regarding the role of OC and its subfractions in bone and energy metabolism and assess current clinical trial evidence relating to the significance and consequences of this relationship in humans.

Efficacy of calcium supplementation for management of overweight and obesity: systematic review of randomized clinical trials

Numerous dietary supplements are marketed as slimming aids, but the efficacy of most has not been proven. One such slimming aid is calcium. Presented here are the results of a systematic review that aimed to evaluate the evidence for or against the efficacy of calcium supplements for body-weight reduction in overweight and obese individuals. Electronic searches were conducted to identify relevant randomized clinical trials of at least 6 months duration. No restrictions of age, gender, language, or time of publication were imposed. Two reviewers independently determined the eligibility of studies, assessed the reporting quality of the studies included, and extracted data. Twenty-four eligible trials were identified, and seven were included. Five of the randomized clinical trials included were not of good reporting quality. A meta-analysis revealed a small, significant reduction in body weight for calcium compared with placebo (mean difference, (-) 0.74 kg; 95% confidence interval, (-) 1.00-(-) 0.48). A small, significant reduction in body fat favoring calcium over placebo was also noted (mean difference, (-) 0.93 kg; 95% confidence interval, (-) 1.16-(-) 0.71). In conclusion, the evidence from randomized clinical trials suggests calcium supplementation generates small, statistically significant weight loss in overweight and obese individuals, but the clinical relevance of this finding is uncertain.

Areal and volumetric bone mineral density and geometry at two levels of protein intake during caloric restriction: a randomized, controlled trial

Weight reduction induces bone loss by several factors, and the effect of higher protein (HP) intake during caloric restriction on bone mineral density (BMD) is not known. Previous study designs examining the longer-term effects of HP diets have not controlled for total calcium intake between groups and have not examined the relationship between bone and endocrine changes. In this randomized, controlled study, we examined how BMD (areal and volumetric), turnover markers, and hormones [insulin-like growth factor 1 (IGF-1), IGF-binding protein 3 (IGFBP-3), 25-hydroxyvitamin D, parathyroid hormone (PTH), and estradiol] respond to caloric restriction during a 1-year trial using two levels of protein intake. Forty-seven postmenopausal women (58.0 ± 4.4 years; body mass index of 32.1 ± 4.6 kg/m(2) ) completed the 1-year weight-loss trial and were on a higher (HP, 24%, n = 26) or normal protein (NP, 18%, n = 21) and fat intake (28%) with controlled calcium intake of 1.2 g/d. After 1 year, subjects lost 7.0% ± 4.5% of body weight, and protein intake was 86 and 60 g/d in the HP and NP groups, respectively. HP compared with NP diet attenuated loss of BMD at the ultradistal radius, lumbar spine, and total hip and trabecular volumetric BMD and bone mineral content of the tibia. This is consistent with the higher final values of IGF-1 and IGFBP-3 and lower bone-resorption marker (deoxypyridinoline) in the HP group than in the NP group (p < .05). These data show that a higher dietary protein during weight reduction increases serum IGF-1 and attenuates total and trabecular bone loss at certain sites in postmenopausal women.

Exenatide treatment did not affect bone mineral density despite body weight reduction in patients with type 2 diabetes

Preclinical studies suggest that incretin-based therapies may be beneficial for the bone; however, clinical data are largely lacking. We assessed whether the differential effects of these therapies on body weight differed with respect to their effect on bone mineral density (BMD) and markers of calcium homeostasis in patients with type 2 diabetes (T2D). Sixty-nine metformin-treated patients with T2D were randomized to exenatide twice daily (n = 36) or insulin glargine once daily (n = 33). Total body BMD, measured by dual-energy X-ray absorptiometry, and serum markers of calcium homeostasis were assessed before and after 44-week treatment. Exenatide or insulin glargine treatment decreased body weight by 6%. Endpoint BMD was similar in both groups after 44-week therapy (LSmean ± s.e.m. between-group difference -0.002 ± 0.007 g/cm(2) ; p = 0.782). Fasting serum alkaline phosphatase, calcium and phosphate remained unaffected. Forty-four-week treatment with exenatide or insulin glargine had no adverse effects on bone density in patients with T2D, despite differential effects on body weight.

A comparative effectiveness study of bone density changes in women over 40 following three bone health plans containing variations of the same novel plant-sourced calcium

BACKGROUND

The US Surgeon General's Report on Bone Health suggests America's bone-health is in jeopardy and issued a "call to action" to develop bone-health plans incorporating components of (1) improved nutrition, (2) increased health literacy, and (3) increased physical activity.

OBJECTIVE

To conduct a Comparative Effectiveness Research (CER) study comparing changes in bone mineral density in healthy women over-40 with above-average compliance when following one of three bone health Plans incorporating the SG's three components.

METHODS

Using an open-label sequential design, 414 females over 40 years of age were tested, 176 of whom agreed to participate and follow one of three different bone-health programs. One Plan contained a bone-health supplement with 1,000 IUs of vitamin D(3 )and 750 mg of a plant-sourced form of calcium for one year. The other two Plans contained the same plant form of calcium, but with differing amounts of vitamin D(3) and other added bone health ingredients along with components designed to increase physical activity and health literacy. Each group completed the same baseline and ending DXA bone density scans, 43-chemistry blood test panels, and 84-item Quality of Life Inventory (QOL). Changes for all subjects were annualized as percent change in BMD from baseline. Using self-reports of adherence, subjects were rank-ordered and dichotomized as "compliant" or "partially compliant" based on the median rating. Comparisons were also made between the treatment groups and two theoretical age-adjusted expected groups: a non-intervention group and a group derived from a review of previously published studies on non-plant sources of calcium.

RESULTS

There were no significant differences in baseline BMD between those who volunteered versus those who did not and between those who completed per protocol (PP) and those who were lost to attrition. Among subjects completing per protocol, there were no significant differences between the three groups on baseline measurements of BMD, weight, age, body fat and fat-free mass suggesting that the treatment groups were statistically similar at baseline. In all three treatment groups subjects with above average compliance had significantly greater increases in BMD as compared to the two expected-change reference groups. The group following the most nutritionally comprehensive Plan outperformed the other two groups. For all three groups, there were no statistically significant differences between baseline and ending blood chemistry tests or the QOL self-reports.

CONCLUSIONS

The increases in BMD found in all three treatment groups in this CER stand in marked contrast to previous studies reporting that interventions with calcium and vitamin D(3) reduce age-related losses of BMD, but do not increase BMD. Increased compliance resulted in increased BMD levels. No adverse effects were found in the blood chemistry tests, self-reported quality of life and daily tracking reports. The Plans tested suggest a significant improvement over the traditional calcium and vitamin D(3) standard of care.

Metabolic bone disease in the bariatric surgery patient

Bariatric surgery has proven to be a life-saving measure for some, but for others it has precipitated a plethora of metabolic complications ranging from mild to life-threatening, sometimes to the point of requiring surgical revision. Obesity was previously thought to be bone protective, but this is indeed not the case. Morbidly obese individuals are at risk for metabolic bone disease (MBD) due to chronic vitamin D deficiency, inadequate calcium intake, sedentary lifestyle, chronic dieting, underlying chronic diseases, and the use of certain medications used to treat those diseases. After bariatric surgery, the risk for bone-related problems is even greater, owing to severely restricted intake, malabsorption, poor compliance with prescribed supplements, and dramatic weight loss. Patients presenting for bariatric surgery should be evaluated for MBD and receive appropriate presurgical interventions. Furthermore, every patient who has undergone bariatric surgery should receive meticulous lifetime monitoring, as the risk for developing MBD remains ever present.

Three-month weight reduction does not compromise bone strength in obese premenopausal women

Weight loss is claimed to cause bone loss. This prospective 12-month study evaluated effects of 3-month group-based weight loss with VLED on body composition, bone mass and strength (DXA and pQCT), muscle performance and biomarkers of bone turnover. The assessments were done at baseline and at 3 and 12 months. Sixty-two women of the recruited 75 obese (BMI>30) premenopausal women who completed the study were divided into 3 groups based on the tertiles of weight loss at 3 months. The group means of weight losses were 15.5% (Large), 10.5% (Medium) and 5.9% (Low). Statistical analyses were based on analysis of covariance. Bone turnover increased during the weight reduction period in all groups but practically returned to baseline during the weight maintenance phase. In general, mean bone changes remained marginal (approximately +/-1%) and the amount of weight reduction was not associated with bone loss. The only notable change was the 4% decline in bending strength at the distal radius. These results indicate that in obese premenopausal women, 3-month weight reduction resulted in increased bone turnover but was not deleterious for bone mass or strength at 3 months or after 9-month weight maintenance.

Past and current weight change and forearm bone loss in middle-aged women: the Nord-Trøndelag Health Study, Norway

OBJECTIVE

The aim of this study was to investigate the association between bone loss and weight change before and concurrently to the assessment of forearm bone loss over 4.6 years in a population-based cohort of middle-aged women followed for more than 15 years.

METHODS

Among 8,856 women aged 45 to 60 years attending the first Nord-Trøndelag Health Study study, Norway (1984-1986), a 35% random sample was invited for forearm densitometry at Nord-Trøndelag Health Study 2 (1995-1997), and 2,188 women (78%) attended. After an average period of 4.6 years, they were subsequently invited for follow-up densitometry in 2001, and 1,421 women (67.8%) met. Weight and height were measured on all three occasions.

RESULTS

During the total period of observation since baseline (15.5 y), the mean weight had increased by 3.4 kg, mostly in the youngest women. Weight loss had an accelerating and weight gain a decelerating effect on bone loss, and this was observed both for weight change occurring before the bone mineral density follow-up and for concurrent weight change. The relationship between prior weight gain or loss and bone loss seemed to persist, independent of the weight change observed during the period of bone loss assessment.

CONCLUSIONS

Despite no mechanical impact of body weight on the forearm, weight loss in midlife women seems to be associated with a long-lasting negative effect on bone and vice versa for weight gain. This is presumably explained by humoral factors.

Total body bone mineral content and density during weight loss and maintenance on a low- or recommended-dairy weight-maintenance diet in obese men and women

BACKGROUND

Diets high in either dairy or calcium during moderate weight reduction both prevent loss of bone mineral density (BMD) and suppress bone turnover. The purpose of this study was to determine whether recommended dairy and calcium intakes during weight maintenance favorably affect total body BMD (TBBMD) and bone mineral content (TBBMC) in obese adults.

METHODS

Obese men (n=49) and women (n=64), aged 40.8+/-0.6 years, underwent 12 weeks of moderate energy restriction (approximately 1200 kcal/day) followed by 24 weeks on either a low or recommended dairy weight maintenance diet. The TBBMC and TBBMD values were measured using dual energy X-ray absorptiometry at baseline, 12, 24 and 36 weeks. Concentrations of calcium, intact parathyroid hormone (iPTH), 25OH and 1,25 (OH)(2) vitamin D in plasma were also measured. Data were analyzed using a two-factor repeated measures analysis of variance.

RESULTS

After weight loss, women exhibited a small, but statistically significant, increase in TBBMC (1.17+/-0.57%), whereas TBBMD increased in the men (1.34+/-0.28%). The iPTH concentration decreased significantly in all subjects. Despite significantly greater intakes of calcium, vitamin D and protein compared with the recommended dairy diet, there were no treatment-related differences in outcome variables after 24 weeks of weight maintenance. The TBBMC remained unchanged in women during weight stabilization; both TBBMC and TBBMD decreased in men (-1.59+/-0.51% and -0.70+/-0.25%, respectively).

CONCLUSIONS

In summary, results of this study do not provide convincing evidence that moderate weight loss through energy restriction and mild exercise reduces TBBMC in obese men and women. Similarly, a weight-maintenance diet providing the recommended daily servings of dairy does not seem to affect changes in BMC after weight loss.

Energy restriction is associated with lower bone mineral density of the tibia and femur in lean but not obese female rats

Energy restriction decreases bone mineral density (BMD), and epidemiological studies suggest that the risk of weight loss-induced bone loss is greater in lean than in heavier individuals. Our goal in this study was to determine how bone density and geometry respond to energy restriction in mature obese rats compared with lean rats. At 6 mo of age, 36 diet-induced obese and lean female Sprague-Dawley rats were allocated to control (CTL; ad libitum; n = 18) and energy-restricted (EnR; 40% restriction; n = 18) diets. After 10 wk of dietary intervention, obese EnR rats lost more weight (-91 +/- 34 g) than lean EnR rats(-61 +/- 14 g) (P < 0.02), [corrected] whereas body weight did not change significantly in the 2 CTL groups (14 +/- 23 g). Only the lean EnR (and not obese EnR) rats showed lower BMD compared with CTL rats at the tibia, distal, and proximal femur and femoral neck, and trabecular bone volume (P < 0.05). Serum estradiol declined in lean EnR rats compared with baseline (P < 0.05) but not in the obese EnR rats. In addition, the final serum 25-hydroxyvitamin D (25OHD) concentration was higher (P < 0.05) in obese than in lean EnR rats. Serum parathyroid hormone decreased (P < 0.05) from baseline to final in lean and obese CTL, but not EnR rats. These data support the hypothesis that energy restriction in lean rats compared with obese rats is more detrimental to bone, and it is possible that the greater decline in estrogen and lower levels of 25OHD contribute to this effect.

Investigation of the effect of high dairy diet on body mass index and body fat in overweight and obese children

OBJECTIVE

To investigate whether an increase in dairy food consumption improves the changes in BMI and adiposity in children on an energy restricted diet.

METHODS

Overweight and obese children (n = 120, age: 12-18 y, BMI: 27-40 kg/m2) were randomized to receive a calorie restricted diet providing a 500 kcal/d deficit from total energy expenditure and two (n = 40), three (n = 40) or four (n = 40) servings of dairy products/day. Anthropometric measurements in addition to serum hs-CRP and lipid profile were measured at baseline and after 12 weeks.

RESULTS

Among the 96 children who completed the study, significant reductions in overall BMI, BMI z-score, weight, total body fat percentage and total body fat mass were observed (p < 0.001) but these reductions were not significantly affected by increasing dairy intake (p > 0.05). Overall waist/hip ratio, Serum vitamin D and lipid profile did not change significantly (p > 0.05) apart from a significant increase in HDL-cholesterol (p < 0.001) which was independent of dairy intake (p > 0.05).

CONCLUSION

Increased intake of dairy products does not lead to an augmented change in BMI, weight and body fat in overweight and obese children beyond what is achieved by calorie restriction.

Effect of dairy and non-dairy calcium on fecal fat excretion in lactose digester and maldigester obese adults

Background

The effect of dietary calcium on fecal fat excretion in lactose maldigestion is not known.

Objective

To investigate the effect of dairy and nondairy dietary calcium on fecal fat excretion in lactose digesters and maldigesters during moderate energy restriction.

Design

A randomized cross-over trial comparing the effect of 500 mg vs. 1500 mg dairy and nondairy calcium on fecal fat excretion in 34 healthy adults during moderate (− 30%) energy restriction diet-induced weight loss for 12 weeks. The participants were classified as lactose digester or maldigester on the basis of breath hydrogen test.

Measurements

Anthropometric parameters and body composition, resting energy expenditure, energy and nutrient intake, fecal fat, physical activity, blood pressure, blood and urine sampling for pertinent measurements.

Results

Fecal fat loss expressed as percent of fat intake was significantly higher with 1500 mg (high-Ca) compared to 500 mg (low-Ca) calcium intake per day (mean: 3.0%; the 95% CI: 2.3 to 3.7%; P <0.001) independent of calcium source and lactose digestion status.

Conclusions

During moderate energy restriction induced weight loss a high-Ca diet causes an increase in fecal fat excretion independent of calcium source. Calcium intake related fecal fat loss is also independent of the ability to digest lactose and it is not diminished over time.

[Association among weight loss, bone mass, body composition and dietary intake of post-pubertal obese adolescents]

OBJECTIVE

To verify the effects of weight loss on bone mass of obese adolescents submitted to a nutritional intervention based on a hypocaloric diet and nutritional advice over a nine-month-period.

METHODS

Anthropometry, body composition, BMD and dietary intake were evaluated.

RESULTS

Fifty-five adolescents, 78.2% females, within an average age of 16.6 (1.4) years old participated in the study. Sixteen participants who completed the study did not lose weight. The group that adhered to the nutritional intervention had a mean weight loss of 6.2 (4.6)% baseline. There was a significant increase in total BMD and bone mineral content (BMC) in those adolescents who did not lose weight, while increased BMC and bone area were verified in participants who lost weight, mainly when associated with body composition alterations while changing weight.

CONCLUSION

The increment in bone mineral density, even throughout weight loss, has showed no negative effect on bone mass and has also emphasized the importance of nutritional improvement in total bone mass during adolescence.

Blood lead levels and bone turnover with weight reduction in women

High bone turnover states are known to raise blood lead levels (BPb). Caloric restriction will increase bone turnover, yet it remains unknown if weight reduction increases BPb due to mobilization of skeletal stores. We measured whole blood Pb levels ((206)Pb) by inductively coupled plasma mass spectrometry in 73 women (age 24-75 years; BMI 23- 61 kg/m(2)) before and after 6 months of severe weight loss (S-WL), moderate weight loss (M-WL), or weight maintenance (WM). Baseline BPb levels were relatively low at 0.2-6.0 microg/dl, and directly associated with age (r=0.49, P<0.0001). After severe WL (-37.4+/-9.3 kg, n=17), BPb increased by 2.1+/-3.9 microg/dl (P<0.05), resulting in BPb levels of 1.3-12.5 microg/dl. M-WL (-5.6+/-2.7 kg, n=39) and WM (0.3+/-1.3 kg, n=17) did not result in an increase in BPb levels (0.5+/-3.2 and 0.0+/-0.7 microg/dl, M-WL and WM, respectively). BPb levels increased more with greater WL (r=0.24, P<0.05). Bone turnover markers increased only with severe WL and were directly correlated with WL. At baseline, higher calcium intake was associated with lower BPb (r=-0.273, P<0.02), however, this association was no longer present after 6 months. Severe weight reduction in obese women increases skeletal bone mobilization and BPb, but values remain well below levels defined as Pb overexposure.

Bone mineral density and its relationship with body mass index in postmenopausal women with type 2 diabetes mellitus in mainland China

Bone mineral density (BMD) and its association with body mass index (BMI) are uncertain in postmenopausal women with type 2 diabetes mellitus (T2DM) in mainland China. This study was performed to assess this association including 1,042 postmenopausal women with T2DM and 919 non-diabetic control subjects. Bone mineral density of the posteroanterior spine and of the left hip was measured by use of dual-energy X-ray absorptiometry. Diabetic participants were divided into three groups according to BMI, i.e. low BMI (DML < 18.5 kg/m(2)), intermediate BMI (DMM 18.5-24.9 kg/m(2)), and high BMI (DMH >or= 25 kg/m(2)). The BMD values of diabetic subjects between groups exhibited a significant gradient difference, with DML < DMM < DMH. On the fitting curves, where BMD in various skeletal regions varied with age, BMDs of DML were approximately 15% lower than those of DMM, and those of DMM were approximately 10% lower than those of DMH. For prevalence and risks of osteoporosis a gradient difference was observed among diabetic groups, DML > DMM approximately control > DMH. The osteoporosis risk was higher for the hip than for the lumbar spine, especially in DML. This study indicated that postmenopausal women with T2DM had higher BMD and lower osteoporosis risk in the lumbar spine, and that lower BMI was an indicator of osteoporosis in mainland China.

Dairy and weight loss hypothesis: an evaluation of the clinical trials

This review evaluates evidence from clinical trials that assessed the effect of dairy product or calcium intake, with or without concomitant energy restriction, on body weight and adiposity. Of 49 randomized trials assessing the effect of dairy products or calcium supplementation on body weight, 41 showed no effect, two demonstrated weight gain, one showed a lower rate of gain, and five showed weight loss. Four of 24 trials report differential fat loss. Consequently, the majority of the current evidence from clinical trials does not support the hypothesis that calcium or dairy consumption aids in weight or fat loss.

Effect of weight loss and exercise therapy on bone metabolism and mass in obese older adults: a one-year randomized controlled trial

BACKGROUND

Although weight loss and exercise ameliorates frailty and improves cardiac risk factors in obese older adults, the long-term effect of lifestyle intervention on bone metabolism and mass is unknown.

OBJECTIVE

The objective was to evaluate the effects of diet-induced weight loss in conjunction with exercise on bone metabolism and mass in obese older adults.

DESIGN AND SETTING

We conducted a one-year randomized, controlled clinical trial in a university-based research center.

PARTICIPANTS

Twenty-seven frail, obese (body mass index = 39 +/- 5 kg/m(2)), older (age 70 +/- 5 yr) adults participated in the study.

INTERVENTION

Participants were randomly assigned to diet and exercise (treatment group; n = 17) or no therapy (control group; n = 10).

OUTCOME MEASURES

Body weight decreased in the treatment group but not in the control group (-10 +/- 2 vs. +1 +/- 1%, P < 0.001). Compared with the control group, the treatment group had greater changes in bone mass, bone markers, and hormones, including 1) bone mineral density (BMD) in total hip (0.1 +/- 2.1 vs. -2.4 +/- 2.5%), trochanter (0.2 +/- 3.3 vs. -3.3 +/- 3.1%), and intertrochanter (0.3 +/- 2.7 vs. -2.7 +/- .3.0%); 2) C-terminal telopeptide (12 +/- 35 vs. 101 +/- 79%) and osteocalcin (-5 +/- 15 vs. 66 +/- 61%); and 3) leptin (2 +/- 12 vs. -30 +/- 25%) and estradiol (0.1 +/- 14% vs. -14 +/- 21%) (all P < 0.05). Changes in weight (r = 0.55), bone markers (r = -0.54), and leptin (r = 0.61) correlated with changes in hip BMD (all P < 0.05).

CONCLUSION

Weight loss, even when combined with exercise, decreases hip BMD in obese older adults. It is not known whether the beneficial effects of weight loss and exercise on physical function lower the overall risk of falls and fractures, despite the decline in hip BMD.

Influence of moderate energy restriction and seafood consumption on bone turnover in overweight young adults

BACKGROUND

Overweight and obesity are increasing in young adults. However, moderate energy restriction aimed at lowering body weight may promote bone turnover and bone loss. Inclusion of fish or fish oils in a weight-loss diet may attenuate these adverse skeletal effects.

OBJECTIVE

We examined the effects of incorporating fish or fish oil into an energy-restricted diet on bone turnover markers in young overweight adults.

DESIGN

While following a strict hypoenergetic (-30% relative to estimated requirements) diet for 8 wk, 276 overweight men and women [body mass index (in kg/m(2)): 27.5-32.5; age: 20-40 y) were randomly assigned to 1 of 4 dietary groups: sunflower-oil capsules (3 g/d; control), cod (3 x 150 g/wk), salmon (3 x 150 g/wk), and fish-oil capsules (3 g/d). Body weight, bone biomarkers, and 25-hydroxyvitamin D were measured at baseline and endpoint. Data were analyzed with repeated-measures analysis of variance and general linear models.

RESULTS

The mean (+/-SD) weight loss was 5.14 +/- 3.0 kg (5.8% +/- 3.2% body weight) during the 8 wk in the 4 dietary groups combined. Urinary N-telopeptides of type I collagen and serum C-terminal telopeptide of type I collagen increased (P < 0.05), whereas serum osteocalcin (but not bone-specific alkaline phosphatase) decreased (P < 0.05) from baseline to endpoint. Increased fish or fish-oil consumption had no effect (P > 0.1) on the changes in bone markers induced by weight loss. In contrast, increased salmon consumption increased serum 25-hydroxyvitamin D (P < 0.01).

CONCLUSIONS

A nutritionally adequate but energy-restricted diet, with different contents of n-3 fatty acids, which resulted in modest weight loss, unfavorably altered bone turnover markers in young overweight adults. Such changes were not prevented by increased fish or fish-oil consumption.

A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study

Background

This study evaluated a specialized whey fraction (Prolibra™, high in leucine, bioactive peptides and milk calcium) for use as a dietary supplement to enhance weight loss.

Methods

This was a randomized, double-blind, parallel-arm, 12-week study. Caloric intake was reduced 500 calories per day. Subjects consumed Prolibra or an isocaloric ready-to-mix beverage 20 minutes before breakfast and 20 minutes before dinner. Body fat and lean muscle tissue were measured by dual-energy x-ray absorptiometry (DEXA). Body weight and anthropometric measurements were recorded every 4 weeks. Blood samples were taken at the beginning and end of the study. Statistical analyses were performed on all subjects that completed (completer analysis) and all subjects that lost at least 2.25 kg of body weight (responder analysis). Within group significance was determined at P < 0.05 using a two-tailed paired t-test and between group significance was determined using one way analysis of covariance with baseline data as a covariate.

Results

Both groups lost a significant amount of weight and the Prolibra group tended to lose more weight than the control group; however the amount of weight loss was not significantly different between groups after 12 weeks. Prolibra subjects lost significantly more body fat compared to control subjects for both the completer (2.81 vs. 1.62 kg P = 0.03) and responder (3.63 vs. 2.11 kg, P = 0.01) groups. Prolibra subjects lost significantly less lean muscle mass in the responder group (1.07 vs. 2.41 kg, P = 0.02). The ratio of fat to lean loss (kg fat lost/kg lean lost) was much larger for Prolibra subjects for both completer (3.75 vs. 1.05) and responder (3.39 vs. 0.88) groups.

Conclusion

Subjects in both the control and treatment group lost a significant amount of weight with a 500 calorie reduced diet. Subjects taking Prolibra lost significantly more body fat and showed a greater preservation of lean muscle compared to subjects consuming the control beverage. Because subjects taking Prolibra lost 6.1% of their body fat mass, and because a 5% reduction of body fat mass has been shown to reduce the risk of obesity related disease, the results have practical significance.

Effects of additional resistance training during diet-induced weight loss on bone mineral density in overweight premenopausal women

Bone loss accompanies a diet-induced weight loss and could be prevented with a combination of exercises. This study was conducted to examine the effects of additional resistance training during diet-induced weight loss on whole-body and selected regional bone mineral density (BMD). The participants of a 14-week weight-loss study were 42 overweight premenopausal Japanese women who were randomly placed in either a diet-only group (D; n = 21) or a diet plus resistance training group (DR; n = 21). Whole-body BMD and body composition, lumbar spine BMD, and 1/3 radial BMD were measured by dual-energy X-ray absorptiometry before and after the intervention. Bone formation and resorption markers were also measured. Thirty-five participants (83%) completed the study. Individuals in groups D (n = 17) and DR (n = 18) lost 6.2 +/- 3.5 kg and 8.6 +/- 3.6 kg body weight, respectively. Reductions in percentage fat mass and fat mass in group DR were significantly greater than in group D; lean mass decreased significantly in both groups. The effect of time on whole-body BMD was significant (-0.3%); however, whole-body bone mineral content, lumbar spine BMD, and 1/3 radial BMD remained unchanged. There were no significant timeby-group interactions in the whole-body and regional BMD and bone markers. These results suggest that additional resistance training during weight loss has no effect on BMD in overweight premenopausal Japanese women. Further long-term studies with large numbers of subjects are needed.

The health benefits of calcium citrate malate: a review of the supporting science

There has been considerable investigation into the health benefits of calcium citrate malate (CCM) since it was first patented in the late 1980s. This chapter is a comprehensive summary of the supporting science and available evidence on the bioavailability and health benefits of consuming CCM. It highlights the important roles that CCM can play during various life stages. CCM has been shown to facilitate calcium retention and bone accrual in children and adolescents. In adults, it effectively promotes the consolidation and maintenance of bone mass. In conjunction with vitamin D, CCM also decreases bone fracture risk in the elderly, slows the rate of bone loss in old age, and is of benefit to the health and well-being of postmenopausal women. CCM is exceptional in that it confers many unique benefits that go beyond bone health. Unlike other calcium sources that necessitate supplementation be in conjunction with a meal to ensure an appreciable benefit is derived, CCM can be consumed with or without food and delivers a significant nutritional benefit to individuals of all ages. The chemistry of CCM makes it a particularly beneficial calcium source for individuals with hypochlorydia or achlorydia, which generally includes the elderly and those on medications that decrease gastric acid secretion. CCM is also recognized as a calcium source that does not increase the risk of kidney stones, and in fact it protects against stone-forming potential. The versatile nature of CCM makes it a convenient and practical calcium salt for use in moist foods and beverages. The major factor that may preclude selection of CCM as a preferred calcium source is the higher cost compared to other sources of calcium commonly used for fortification (e.g., calcium carbonate and tricalcium phosphate). However, formation of CCM directly within beverages or other fluid foods and/or preparations, and the addition of a concentrated CCM solution or slurry, are relatively cost-effective methods by which CCM can be incorporated into finished food and beverage products.

Self-reported changes in dietary calcium and energy intake predict weight regain following a weight loss diet in obese women

This study examined relationships between changes in dietary calcium intake, energy intake, and body weight following a weight loss diet. One hundred three overweight or obese women lost weight over 22 wk. Dietary calcium and energy intake were assessed using the Block 98 FFQ (Block) and 5-d food records (FR) at intervention end and 6- and 18-mo follow-up. Pearson correlations were used to relate changes in dietary calcium to energy intake. We used regression analyses to examine relationships between changes in dietary calcium, energy intake, and weight regain. Changes in dietary calcium and energy intake were correlated (r = 0.32; P = 0.033), but neither variable alone predicted weight regain. From 6- to 18-mo follow-up, greater dietary calcium intake inversely predicted weight regain when controlling for changes in energy intake (P = 0.048 Block and 0.025 FR), whereas higher energy intake positively predicted weight regain when controlling for changes in dietary calcium intake (P = 0.009 Block and 0.049 FR) (combined R(2) = 0.153 Block and 0.178 FR). Dietary calcium may oppose weight regain, reducing the effect of greater energy intake. Our results encourage future research on the potential relationship between dietary calcium and weight loss maintenance and suggest that controlling for dietary calcium may increase the ability of energy intake to predict weight change.

Vitamin D status and parathyroid hormone in obese children before and after weight loss

OBJECTIVE

The roles of vitamin D and parathyroid hormone (PTH) are discussed controversially in obesity, and studies of these hormones in obese children are limited. Therefore, we studied the relationships between PTH, 1,25-dihydroxy-vitamin D (1,25-OH Vit D), 25-hydroxy-vitamin D (25-OH Vit D), weight status, and insulin sensitivity before and after weight loss in obese children.

METHODS

Fasting serum PTH, 1,25-OH Vit D, 25-OH Vit D, inorganic phosphate, calcium, alkaline phosphatase (AP), insulin, glucose, and weight status (SDS-BMI and percentage body fat) were determined in 133 obese children (median age 12.1 years) and compared with 23 non-obese children. Furthermore, these parameters were analyzed in 67 obese children before and after participating in a 1-year obesity intervention program.

RESULTS

Obese children had significantly (P < 0.001) higher PTH and lower 25-OH Vit D concentrations compared with non-obese children, while calcium, phosphate, AP, and 1,25-OH Vit D did not differ significantly. Changes of PTH (r = 0.23, P = 0.031) and 25-OH Vit D (r = -0.27, P = 0.013) correlated significantly with changes of SDS-BMI, but not with changes of insulin sensitivity (homeostasis model assessment; HOMA-B%). Reduction of overweight in 35 children led to a significant (P < 0.01) decrease of PTH concentrations and an increase in 25-OH Vit D levels.

CONCLUSIONS

PTH levels were positively and 25-OH Vit D concentrations were negatively related to weight status. Since these alterations normalized after weight loss, these changes are consequences rather than causes of overweight. A relationship between PTH, vitamin D, and insulin sensitivity based on the HOMA index was not found in obese children. Further longitudinal clamp studies are necessary to study the relationship between vitamin D and insulin sensitivity.