Moderate energy restriction increases bone resorption in obese postmenopausal women

Changes in bone mineral density in women following 1-year gastric bypass surgery

BACKGROUND

Roux-en-Y gastric bypass (RYGB) surgery is the gold standard surgical treatment for obesity. However, unintended nutritional deficiencies following this surgery are common, including changes in bone metabolism. We assessed changes in bone mineral density (BMD), nutritional compounds, and bone resorption markers before and 1 year following RYGB surgery.

METHODS

Our study included 22 female patients with class II/III obesity. A clinical questionnaire, a 24-h recall, blood and urine samples, and dual-energy X-ray absorptiometry were provided.

RESULTS

Mean age was 37.2 ± 9.6 years; 86 % were Caucasian and 77.2 % were premenopausal. Mean preoperative body mass index was 44.4 ± 5.0 and 27.5 ± 4.5 kg/m(2) at 1-year follow-up (p < 0.001). 25-OH-vitamin D-levels were similar in both periods [11.7 (9.7-18.0) vs. 15.7 (10.2-2.7) pg/dL, p = 0.327]. Serum N-telopeptide (16.3 ± 3.4 vs. 38.2 ± 7.0 nM BCE, p < 0.001) and parathyroid hormone (45.4 ± 16.7 vs. 62.7 ± 28.9 pg/mL, p = 0.026) increased after RYGB surgery, reflecting bone resorption. BMD decreased after RYGB surgery in the lumbar spine (1.13 ± 0.11 vs. 1.04 ± 0.09 g/cm(2), p = 0.001), femoral neck (1.03 ± 0.15 vs. 0.94 ± 0.16 g/cm(2), p = 0.001), and total femur (1.07 ± 0.11 vs. 0.97 ± 0.15 g/cm(2), p = 0.003).

CONCLUSIONS

Decreased BMD in the lumbar spine, femoral neck, and total femur is detectable in women 1 year after RYGB surgery. Calcium malabsorption, caused by vitamin D deficiency and increased bone resorption, is partially responsible for these outcomes and should be targeted in future clinical trials.

Dapagliflozin has no effect on markers of bone formation and resorption or bone mineral density in patients with inadequately controlled type 2 diabetes mellitus on metformin

AIMS

Dapagliflozin, a selective sodium-glucose cotransporter 2 (SGLT2) inhibitor, reduces hyperglycaemia in patients with type 2 diabetes (T2DM) by increasing urinary glucose excretion. Owing to its mechanism of action, dapagliflozin could potentially affect the renal tubular transportation of bone minerals. Therefore, markers of bone formation and resorption and bone mineral density (BMD) were evaluated in patients with T2DM after 50 weeks of dapagliflozin treatment.

METHODS

This international, multi-centre, randomized, parallel-group, double-blind, placebo-controlled study (ClinicalTrials.gov NCT00855166) enrolled patients with T2DM (women 55-75 years and men 30-75 years; HbA1c 6.5-8.5%; BMI ≥ 25 kg/m(2) ; body weight ≤ 120 kg) whose T2DM was inadequately controlled on metformin. One hundred and eighty-two patients were randomly assigned 1:1 to receive dapagliflozin 10 mg/day or placebo added to open-label metformin for a 24-week double-blind treatment period followed by a 78-week site- and patient-blinded extension period. At week 50, serum markers of bone formation (procollagen type 1 N-terminal propeptide; P1NP) and resorption (C-terminal cross-linking telopeptides of type I collagen; CTX), bone mineral density (BMD) as assessed by standardized Dual-Energy X-ray Absorptiometry (DXA) measurements and adverse events of fracture were evaluated as safety objectives.

RESULTS

One hundred and sixty-five patients (90.7%) completed the first 50 weeks. Compared with placebo, no significant changes from baseline in P1NP, CTX or BMD were identified over 50 weeks of dapagliflozin treatment, with no significant treatment-by-gender interactions. No fractures were reported.

CONCLUSIONS

Dapagliflozin had no effect on markers of bone formation and resorption or BMD after 50 weeks of treatment in both male and post-menopausal female patients whose T2DM was inadequately controlled on metformin.

Behavioral approaches to weight control: a review of current research

Weight management is a salient issue for women. Studies of behavioral, pharmacological and surgical interventions indicate that women comprise the majority of patients presenting for weight-loss treatment. In this review we discuss the health impact of obesity for women, review behavioral treatments for adult overweight and obesity, and address topics of particular relevance for women, including concerns that weight-loss treatment may precipitate the development of eating pathology, as well as time periods of high risk for weight gain such as pregnancy and menopause.

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.

Very-low-energy diets and morbidity: a systematic review of longer-term evidence

Evidence from the literature supports the safe use of very-low-energy diets (VLED) for up to 3 months in supervised conditions for patients who fail to meet a target weight loss using a standard low-fat, reduced-energy approach. There is, however, a need for longer-term outcomes on obesity and associated morbidities following a VLED. The present systematic review aims to investigate longer-term outcomes from studies using VLED, with a minimum duration of 12 months, published between January 2000 and December 2010. Studies conducted in both children and adults, with a mean/median BMI of ≥ 28 kg/m2 were included. PubMed, MEDLINE, Web of Science and Science Direct were searched. Reference lists of studies and reviews were manually searched. Weight loss or prevention of weight gain and morbidities were the main outcomes assessed. A total of thirty-two out of 894 articles met the inclusion criteria. The duration of the studies ranged from 12 months to 5 years. Periods of VLED ranged from 25 d to 9 months. Several studies incorporated aspects of behaviour therapy, exercise, low-fat diets, low-carbohydrate diets or medication. Current evidence demonstrates significant weight loss and improvements in blood pressure, waist circumference and lipid profile in the longer term following a VLED. Interpretation of the results, however, was restricted and conclusions with which to guide best practice are limited due to heterogeneity between the studies. The present review clearly identifies the need for more evidence and standardised studies to assess the longer-term benefits from weight loss achieved using VLED.

Alcohol consumption and bone mineral density in elderly women

OBJECTIVE

Findings regarding alcohol consumption and bone mineral density (BMD) in elderly women have been inconsistent. The objective of the present study was to explore the association of alcohol intake with BMD in elderly women.

DESIGN

This cohort study included women from the population-based Kuopio Osteoporosis Risk Factor and Prevention - Fracture Prevention Study (OSTPRE-FPS). Alcohol intake and potential confounders were assessed at baseline and after 3 years of follow-up using a lifestyle questionnaire. In addition, an FFQ was distributed in the third year to measure dietary intake, including alcohol. Women underwent BMD measurements at the femoral neck and lumbar spine at baseline and after 3 years of follow-up.

SETTING

Kuopio Province, Finland.

SUBJECTS

Three hundred elderly women (mean age 67·8 years) who provided both BMD measurements and FFQ data.

RESULTS

Alcohol consumption estimated from the FFQ and lifestyle questionnaire was significantly associated with BMD at both measurement sites after adjustment for potential confounders, including lifestyle and dietary factors (P < 0·05). Using the FFQ, women drinking >3 alcoholic drinks/week had significantly higher BMD than abstainers, 12·0 % at the femoral neck and 9·2 % at the lumbar spine. Results based on the lifestyle questionnaire showed higher BMD values for all alcohol-consuming women at the femoral neck and for women drinking 1-3 alcoholic beverages/week at the lumbar spine, compared with non-users.

CONCLUSIONS

The results from OSTPRE-FPS suggest that low to moderate alcohol intake may exert protective effects on bone health in elderly women.

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.

High bone density and bone health

The aim of this paper is to review the main aspects related to high bone density (HBD) as well as to discuss the physiologic mechanisms involved in bone health. There are still no well-defined criteria for identification of individuals with HBD and there are few studies on the topic. Most studies demonstrate that overweight, male gender, black ethnic background, physical activity, calcium and fluoride intake and use of medications such as statins and thiazide diuretics play a relevant and positive role on bone mineral density. Moreover, it is known that individuals with certain diseases such as obesity, diabetes, estrogen receptor-positive breast or endometrial cancer have greater bone density than healthy individuals, as well as athletes having higher bone density than non-athletes does not necessarily mean that they have healthy bones. A better understanding of risk and protective factors may help in the management of patients with bone frailty and have applicability in the treatment and in the prevention of osteoporosis, especially intervening on non-modifiable risk factors.

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.

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.

Urinary heavy metals and associated medical conditions in the US adult population

Health effects of heavy metals have been widely investigated, but further evaluation is required to comprehensively delineate their toxicity. Using data from the 2007-2008 National Health and Nutrition Examination Survey, a multivariate logistic regression analysis was performed on 1,857 adults to examine the relationship between urinary heavy metals and various medical conditions. Cardiovascular diseases were correlated to cadmium (OR: 4.94, 95% CI: 1.48-16.56) and lead (OR: 5.32, 95% CI: 1.08-26.21). Asthma was related to tungsten (OR: 1.72, 95% CI: 1.15-2.59) and uranium (OR: 1.52, 95% CI: 1.01-2.28). Hepatotoxicity was associated with molybdenum (OR: 3.09, 95% CI: 1.24-7.73) and uranium (OR: 4.79, 95% CI: 1.74-13.19). Surprising inverse relationships occurred for excessive weight with lead (OR: 0.72, 95% CI: 0.52-0.98), reduced visual acuity with cobalt (OR: 0.65, 95% CI: 0.44-0.95) and cesium (OR: 0.52, 95% CI: 0.35-0.77). This study supports some previous evidence of potential relationships and provides insights for future research.

Evaluation of bone mineral density loss in morbidly obese women after gastric bypass: 3-year follow-up

Studies that evaluate the influence of gastric bypass (RYGP) on bone mass are limited to short-term follow-up. We analysed changes in bone mineral density (BMD) three years after surgery and evaluated the main determinants of the development of bone disease. Prospective study of 59 morbidly obese white women aged 46 ± 8 years. BMD scanning using DEXA and plasma determinations of calcium, parathyroid hormone, 25-hydroxyvitamin D and insulin-like growth factor-I were made prior, at 12 months and 3 years after surgery. In the first postoperative year BMD decreased at femoral neck (FN) 10.2 % and in the lumbar spine (LS) 3.2 %, in the third year it additionally decreased 2.7 % and 3.1 %, respectively. BMD at both sites remained above the values of women of the same age. In the follow-up, 1.7 % developed osteoporosis at FN and 6.8 % at LS. Patients with bone disease were older, the percentage of women with menopause was greater in this group and had lower initial and final values of lean mass. The percentage of BMD loss at FN remained positively associated with the percentage of lean mass loss [β 0.304, p=0.045], and menopause [β 0.337, p=0.025]. Major osteoporotic fracture and hip fracture risk was low even in menopausal patients (3.1 % and 0.40 %, respectively). After RYGP menopausal women and those with greater lean mass loss are at higher risk of BMD loss but progression to osteoporosis is uncommon and the risk of fracture is low.

Diabetes, TZDs, and Bone: A Review of the Clinical Evidence

Evidence from rodent and in vitro models suggests that activation of PPAR-γ by thiazolidinediones (TZDs) causes increased bone marrow adiposity and decreased osteoblastogenesis, resulting in bone loss. TZDs are prescribed for the treatment of diabetes, providing an opportunity to determine whether PPAR-γ activation also impacts bone in humans. In addition, since type 2 diabetes is associated with higher fracture risk, an understanding of the clinical impact of TZDs on bone is needed to guide fracture prevention efforts in this population. This review summarizes current findings regarding type 2 diabetes and increased fracture risk and then considers the available evidence regarding TZD use and bone metabolism in humans.

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.

The high serum monocyte chemoattractant protein-1 in obesity is influenced by high parathyroid hormone and not adiposity

CONTEXT

Chronic high levels of PTH may be associated with up-regulation of proteases and cytokines. Monocyte chemoattractant protein-1 (MCP-1) is an inflammatory cytokine, produced predominantly by macrophages and endothelial cells, and is expressed in adipose tissue. More recently it has been shown that PTH administration increases MCP-1 expression in osteoblasts.

OBJECTIVES

Because both PTH and MCP-1 levels are higher in obesity, the goal was to determine whether the high MCP-1 occurs only in the presence of high serum PTH and is independent of adiposity and examine its relationship with bone mineral density (BMD) and turnover.

DESIGN, SETTING, AND PARTICIPANTS

In this case-control clinical design, 111 eligible women were categorized into four groups: leaner women [body mass index (BMI) 23 ± 2 kg/m(2)] with normal or higher PTH and obese (BMI 44 ± 7 kg/m(2)) with normal or higher PTH.

RESULTS

Serum MCP-1 levels were higher (P < 0.01) in the high (PTH = 74.9 ± 27.0 pg/ml, MCP-1 = 421.5 ± 157.0 pg/ml) compared with normal PTH (PTH = 32.5 ± 10.4 pg/ml, MCP-1 = 322.5 ± 97.8 pg/ml) group, independent of BMI. C-reactive protein and adiponectin were influenced only by BMI and not PTH. MCP-1 was positively associated with osteocalcin and propeptide of type 1 collagen in the leaner (r > 0.3, P < 0.05) but not the obese women and was not associated with BMD in either group.

CONCLUSIONS

Together these data suggest that MCP-1 is higher only in the presence of increased PTH and that adiposity alone cannot explain the higher MCP-1 levels in obesity.

Reference intervals of biochemical bone turnover markers for Saudi Arabian women: a cross-sectional study

Biochemical bone turnover markers (BTMs) provide important information on the diagnosis, therapy and monitoring of metabolic bone diseases including osteoporosis. One goal of antiresorptive therapy in women is to decrease biochemical BTMs to the lower half of reference intervals for healthy pre-menopausal counterparts, using newly developed automated assays of such markers. The main objectives of the present study were to: (1) establish reference interval values for the following biochemical BTMs: serum osteocalcine (s-OC), bone alkaline phosphatase (s-bone ALP), procollagen type 1 N-terminal propeptide (s-PINP), crosslinked C-terminal telopeptide of Type 1 collagen (s-CTX), tartarate-resistant acid phosphatase isoform 5b (s-TRACP-5b) and urinary: CTX (u-CTX), N-telopeptides of type 1 collagen (u-NTX), pyridinoline (u-PYD) and deoxypyridinoline (u-DPD) in randomly selected Saudi healthy pre-menopausal women; (2) study the changes in biochemical BTMs in relation to age in pre- and post-menopausal women and the factors reported to influence bone turnover and (3) determine the effect of menopausal status on BTMs. A total of 2125 women were studied [including (n=1557) pre-, and (n=568) post-menopausal women, respectively, aged 20-79 years]. A total of 765 healthy pre-menopausal women (aged 35-45 years) were used to establish reference intervals for biochemical BTMs. All women studied were medically examined and had their bone mineral density (BMD) values obtained for the lumbar spine (L(1)-L(4)) and femoral neck according to detailed inclusion criteria. In all women, values of biochemical BTMs, decreased with increasing age up to the age of 45 years, increased steeply among women in their 50s and remained increased in post-menopausal women. Significant increases were evident in all biochemical BTMs in post-menopausal women with >5 years since menopause with the exception of s-OC, u-DPD, and u-PYD. Using stepwise multiple linear regression analysis, several variables were identified (depending on the BTM) as determinants of BTMs including age, BMI, parity, FSH, LH, PTH, s-Ca, s-Mg, s-PO(4) and 25(OH)D. In the reference intervals group, there are no significant correlations between any of the biochemical BTMs and age of menarche, day of menstrual cycle, physical activity, total daily dietary calcium and caffeine intakes and parity. It is recommended that the age range 35-45 years should be used when establishing biochemical BTMs reference intervals in Saudi Arabian pre-menopausal women.

Weight loss-induced alterations in serum markers of bone turnover persist during weight maintenance in obese men and women

OBJECTIVE

Moderate weight loss alters bone turnover and reduces bone mineral density in overweight men and women. However, it is not known whether bone turnover is normalized during weight maintenance postweight loss. Thus, the objective of the present study was to examine changes in serum bone turnover markers during 9 months of weight maintenance following weight reduction on a very low-energy diet (VLED) in obese men and women.

METHODS

Thirty-seven men (n = 13) and women (n = 24) aged 50 +/- 9.8 years underwent 3 months of weight reduction on a VLED ( approximately 500 kcal/d) followed by 9 months on either a low-carbohydrate or low-fat weight maintenance diet ( approximately 1600 kcal/d). Concentrations of osteocalcin (OC) and C-terminal peptide of type I collagen (CTX) in serum were measured using enzyme-linked immunosorbent assay at baseline and at months 3, 6, and 12. Serum parathyroid (PTH) concentrations were measured using a chemiluminescent immunoassay at all 4 time points. Data were analyzed using a 3-factor-repeated measures analysis of variance.

RESULTS

Average weight loss was 19% +/- 3% and, during the 9-month weight maintenance period, average weight gain was approximately 3%, with no differences due to diet composition. Serum concentrations of OC and CTX significantly increased after weight reduction and remained elevated during weight maintenance. Serum PTH was reduced after weight loss. Percent changes in OC and CTX were correlated during weight maintenance (r = -0.437, p = 0.008), but not during weight loss. Percent changes in CTX and body weight were negatively correlated during weight loss (r = -0.474, p = 0.003) and maintenance (r = -0.455, p = 0.006).

CONCLUSIONS

Weight loss induced via a VLED may result in an imbalance between bone formation and resorption and accelerate remodeling. The deleterious effect of energy restriction on bone remodeling rate appears to persist during weight maintenance.

[Bone mass loss after sleeve gastrectomy: a prospective comparative study with gastric bypass]

INTRODUCTION

Bariatric surgery is the most effective option for the treatment of patients with a high risk of complications due to their obesity. However, it brings about a series of changes in calcium and vitamin D metabolism and an increase in resorption which lead to a loss of bone mass.

AIM

The objective of this study is to compare sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) as regards loss of bone mass using bone densitometry and bone remodelling markers.

PATIENTS AND METHODS

Fifteen women with morbid obesity were included, 8 by SG and 7 by RYGB, with a mean age of 47.8+/-9 and mean body mass index 43.3+/-3.4. Bone mass measurements were made on the lumbar spine, femur and distal radius, and the bone remodelling markers N-telopeptide (NTx) and bone alkaline phosphatase (BALP), as well as vitamin D levels before and 12 months after surgery.

RESULTS

A significant bone mass loss was observed was observed with SG and RYGB, in the lumbar spine and hip, whilst no differences were observed in the radial. The percentage bone mass loss was less in the column and femur after SG than with RYGB, although it did not reach statistical significance, 4.6%+/-4.4 (mean+/-SD) and 6.3%+/-5.4 (mean+/-SD), respectively. At 12 months the Ntx increased for both types of surgery, and the BAP was only increased for SG.

CONCLUSION

SG causes less, although not significant, bone mass loss compared to RYGB.

Protein intake, weight loss, and bone mineral density in postmenopausal women

BACKGROUND

Higher protein diets are promoted for effective weight loss. Striated tissues in omnivorous diets contain high-quality protein, but limited data exist regarding their effects on bone.

METHODS

To examine the effects of energy restriction-induced weight loss with higher protein omnivorous diets versus lower protein vegetarian diets on bone mineral density in overweight postmenopausal women, two randomized controlled feeding studies were conducted. In Study 1, 28 women consumed 750 kcal/day energy deficit diets with 18% energy from protein via lacto-ovo vegetarian sources (normal protein, n = 15) or 30% energy from protein with 40% of protein from lean pork (higher protein, n = 13, omnivorous) for 12 weeks. In Study 2, 54 women consumed their habitual diet (control, n = 11) or 1,250 kcal/day diets with 16% energy from nonmeat protein sources (n = 14) or 26% energy from protein, including chicken (n = 15) or beef (n = 14) for 9 weeks.

RESULTS

Study 1: With weight loss (normal protein -11.2%, higher protein -10.1%), bone mineral density was not significantly changed in normal protein (-0.003 ± 0.003 g/cm(2), -0.3%) but decreased in higher protein (-0.0167 ± 0.004 g/cm(2), -1. 4%, group-by-time p < .05). Study 2: The control, nonmeat, chicken, and beef groups lost 1.5%, 7.7%, 10.4%, and 8.1% weight and 0.0%, 0.4%, 1.1%, and 1.4% bone mineral density, respectively. The change of bone mineral density was significant for chicken and beef compared with the control (group-by-time, p < .05). Markers of calcium metabolism and bone homeostasis in blood and urine were not changed over time or differentially affected by diet.

CONCLUSION

Consumption of higher protein omnivorous diets promoted decreased bone mineral density after weight loss in overweight postmenopausal women.

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.

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.

[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.

Addition of aerobic exercise to a weight loss program increases BMD, with an associated reduction in inflammation in overweight postmenopausal women

Increased inflammation and weight loss are associated with a reduction in bone mineral density (BMD). Aerobic exercise may minimize the loss of bone and weight loss may contribute to a decrease in cytokines. We tested the hypothesis that aerobic exercise in combination with a weight loss program would decrease circulating concentrations of inflammatory markers, thus mediating changes in BMD. This was a nonrandomized controlled trial. Eighty-six overweight and obese postmenopausal women (50-70 years of age; BMI, 25-40 kg/m(2)) participated in a weight loss (WL; n = 40) or weight loss plus walking (WL + AEX; n = 46) program. Outcome measures included BMD and bone mineral content of the femoral neck and lumbar spine measured by dual energy X-ray absorptiometry, interleukin-6, tumor necrosis factor-alpha, soluble receptors of IL-6, and TNF-alpha (sTNFR1 and sTNFR2; receptors in a subset of the population), VO(2) max, fat mass, and lean mass. Weight decreased in the WL (p < 0.001) and WL + AEX (p < 0.001) groups. VO(2) max increased (p < 0.001) after WL + AEX. There was a 2% increase in femoral neck BMD in the WL + AEX group (p = 0.001), which was significantly different from the WL group. The change in sTNFR1 was significantly associated with the change in femoral neck BMD (p < 0.05). The change in VO(2) max was an independent predictor of the change in femoral neck BMD. Our findings suggest that the addition of aerobic exercise is recommended to decrease inflammation and increase BMD during weight loss in overweight postmenopausal women.

Bone resorption in stroke and institutionalized subjects

Stroke increases the risk of hip fracture on the affected side. Although bone is lost by 1 year, rapidity of onset and relationship with immobility are uncertain. Using the bone resorption marker urinary cross-linked N telopeptide of type I collagen (uNTx), we examined bone resorption in the first 4 weeks after stroke, relating uNTx with bone density and mobility in subjects over 60 years. Two separate control groups acted as comparators, healthy (HC) and institutionalized (IC) controls, the latter to control for the effects of institutionalization. uNTx, urinary calcium (both related to creatinine and log-transformed), heel bone mineral density (BMD), Tinetti scores, and Barthel scores for prestroke function were measured. Log uNTx/Cr was lower in males compared with females, but this difference was not evident in stroke or IC subjects. Log uNTx/Cr was inversely related with BMD in females from both control groups and in male stroke subjects. Tinetti scores were divided into tertiles and were lower in stroke than IC subjects (P < 0.01). Log uNTx/Cr was similar in stroke and IC subjects in the lowest Tinetti tertile. Log uNTx/Cr was higher in stroke subjects of both sexes in the lowest tertile compared with the higher two tertiles combined (P < 0.05) and higher in all tertiles compared with HC subjects (P < 0.05). Subjects with a prestroke Barthel index of < or = 17 had higher log uNTx/Cr compared with HCs. Log uCa/Cr was higher only in male stroke patients. Bone resorption in stroke starts early, and measures to reduce this are merited.

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.

Combination of obesity with hyperglycemia is a risk factor for the presence of vertebral fractures in type 2 diabetic men

Although patients with type 2 diabetes show no bone mineral density (BMD) reduction, fracture risks are known to increase. It is unclear why the patients have an increased risk of fracture despite sufficient BMD. We investigated the relationships of body mass index (BMI), HbA(1c), and urinary C-peptide (uC-peptide) versus BMD, bone metabolic markers, serum adiponectin, and prevalent vertebral fracture (VF). A total of 163 Japanese type 2 diabetic men were consecutively recruited, and radiographic and biochemical data were collected. BMI was positively correlated with BMD at the whole body, lumbar spine, and femoral neck (P < 0.05) and negatively correlated with osteocalcin and urinary N-terminal cross-linked telopeptide of type-I collagen (uNTX) (P < 0.01). HbA(1c) was negatively correlated with osteocalcin (P < 0.01) but not BMD at any site. Subjects were classified into four groups based on BMI and HbA(1c) (group LL BMI < 24 and HbA(1c) < 9, group LH BMI < 24 and HbA(1c) > or = 9, group HL BMI > or = 24 and HbA(1c) < 9, group HH BMI > or = 24 and HbA(1c) > or = 9). Serum adiponectin, osteocalcin, and uNTX were lower and the incidence of VF was higher despite sufficient BMD in the HH group. Multivariate logistic regression analysis adjusted for age, duration of diabetes, uC-peptide, and estimated glomerular filtration rate showed that the HH group was associated with the presence of a VF and multiple VFs (odds ratio [OR] = 3.056, 95% confidence interval [CI] 1.031-9.056, P = 0.0439, and OR = 5.415, 95% CI 1.126-26.040, P = 0.0350, respectively). Combination of obesity with hyperglycemia was a risk factor for VF despite sufficient BMD in diabetic men.

Calorie restriction and bone health in young, overweight individuals

BACKGROUND

Calorie restriction (CR) is promoted to increase longevity, yet this regimen could lead to bone loss and fracture and therefore affect quality of life.

METHODS

Forty-six individuals were randomized to 4 groups for 6 months: (1) healthy diet (control group); (2) 25% CR from baseline energy requirements (CR group); (3) 25% energy deficit by a combination of CR and increased aerobic exercise (CR + EX group); and (4) low-calorie diet (890 kcal/d; goal, 15% weight loss) followed by weight maintenance (LCD group). Bone mineral density (total body and hip by dual-energy x-ray absorptiometry) and serum bone markers (bone-specific alkaline phosphatase, osteocalcin, cross-linked C-telopeptide of type I collagen, and cross-linked N-telopeptide of type I collagen) were measured at baseline and after 6 months.

RESULTS

Mean +/- SE body weight was reduced by -1.0% +/- 1.1% (control), -10.4% +/- 0.9% (CR), -10.0% +/- 0.8% (CR + EX), and -13.9% +/- 0.7% (LCD). Compared with the control group, none of the groups showed any change in bone mineral density for total body or hip. Bone resorption by serum cross-linked C-telopeptide of type I collagen was increased in all 3 intervention groups, with the largest change observed in the LCD group (CR, 23% +/- 10%; CR + EX, 22% +/- 9%; and LCD, 74% +/- 16% vs control, 4% +/- 10%). Serum levels of cross-linked N-telopeptide of type I collagen were also increased in the LCD group. With regard to bone formation, bone alkaline phosphatase levels were decreased in the CR group (-23% +/- 10%) but were unchanged in the CR + EX, LCD, and control groups.

CONCLUSIONS

Moderate CR, with or without exercise, that preserves calcium intake for 6 months leads to large changes in body composition without significant bone loss in young adults. Longer studies with assessments of bone architecture are needed to confirm that CR nutrient-dense diets have no deleterious effect on bone health.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00099151.

Changes in bone mineral density, body composition and adiponectin levels in morbidly obese patients after bariatric surgery

BACKGROUND

Gastric bypass surgery (GBP) is increasingly used as a treatment option in morbid obesity. Little is known about the effects of this surgery on bone mineral density (BMD) and the underlying mechanisms. To evaluate changes on BMD after GBP and its relation with changes in body composition and serum adiponectin, a longitudinal study in morbid obese subjects was conducted.

METHODS

Forty-two women (BMI 45.0 +/- 4.3 kg/m(2); 37.7 +/- 9.6 years) were studied before surgery and 6 and 12 months after GBP. Percentage of body fat (%BF), fat-free mass (FFM), and BMD were measured by dual-energy X-ray absorptiometry and serum adiponectin levels by RIA.

RESULTS

Twelve months after, GBP weight was decreased by 34.4 +/- 6.5% and excess weight loss was 68.2 +/- 12.8%. Significant reduction (p < 0.001) in total BMD (-3.0 +/- 2.1%), spine BMD (-7.4 +/- 6.8%) and hip BMD (-10.5 +/- 5.6%) were observed. Adiponectin concentration increased from 11.4 +/- 0.7 mg/L before surgery to 15.7 +/- 0.7 and 19.8 +/- 1.0 at the sixth and twelfth month after GBP, respectively (p < 0.001). Thirty-seven percent of the variation in total BMD could be explained by baseline weight, initial BMD, BF reduction, and adiponectin at the twelfth month (r (2) = 0.373; p < 0.001). Adiponectin at the twelfth month had a significant and positive correlation with the reduction of BMD, unrelated to baseline and variation in body composition parameters (adjusted correlation coefficient: r = 0.36).

CONCLUSION

GBP induces a significant BMD loss related with changes in body composition, although some metabolic mediators, such as adiponectin increase, may have an independent action on BMD which deserves further study.

Head-to-head comparison of risedronate vs. teriparatide on bone turnover markers in women with postmenopausal osteoporosis: a randomised trial

AIMS

We aimed to compare the effect of risedronate (RIS) and teriparatide (TPTD) (recombinant human parathyroid hormone 1-34) on bone turnover markers in women with postmenopausal osteoporosis.

METHODS

Forty-four Caucasian women (age 65.1 +/- 1.6 years) with postmenopausal osteoporosis were randomly assigned to receive either RIS 35 mg once weekly (n = 22) or TPTD 20 microg once daily (n = 22) for 12 months. Serum N-terminal propeptide of type 1 collagen (P1NP), C-terminal telopeptide of type 1 collagen (CTx), total alkaline phosphatase (ALP) and intact parathyroid hormone (iPTH) were obtained from all women before, 3 and 6 months after treatment initiation. Lumbar spine bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry before and 12 months after treatment initiation.

RESULTS

P1NP, CTx and total ALP levels decreased in RIS group (p < 0.001) and increased in TPTD group (p < 0.001) throughout the treatment. iPTH increased significantly in RIS group (p < 0.05) and decreased in TPTD group (p < 0.001). Finally, lumbar spine BMD increased significantly in both RIS (p = 0.003) and TPTD groups (p < 0.001) without significant differences between them.

CONCLUSIONS

Our data suggest that both serum P1NP and CTx are reliable markers of RIS and TPTD action in women with postmenopausal osteoporosis. In a similar way, serum total ALP can be used as an alternative marker for monitoring both RIS and TPTD action, while iPTH can be used only for TPTD-treated women. The increase in P1NP and CTx after 3 months of treatment with RIS or TPTD can predict the increase in BMD after 12 months of treatment.

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.

Relationships between fat and bone

Body weight impacts both bone turnover and bone density, making it, therefore, an important risk factor for vertebral and hip fractures and ranking it alongside age in importance. The effect of body weight is probably contributed to by both fat mass and lean mass, though in postmenopausal women, fat mass has been more consistently demonstrated to be important. A number of mechanisms for the fat-bone relationship exist and include the effect of soft tissue mass on skeletal loading, the association of fat mass with the secretion of bone active hormones from the pancreatic beta cell (including insulin, amylin, and preptin), and the secretion of bone active hormones (e.g., estrogens and leptin) from the adipocyte. These factors alone probably do not fully explain the observed clinical associations, and study of the actions on bone of novel hormones related to nutrition is an important area of further research. An understanding of this aspect of bone biology may open the way for new treatments of osteoporosis. More immediately, the role of weight maintenance in the prevention of osteoporosis is an important public health message that needs to be more widely appreciated.

Food restriction and simulated microgravity: effects on bone and serum leptin

Leptin is responsible for linking energy metabolism to bone mass. Because astronauts are commonly in negative energy balance during spaceflight, this study was designed to assess individual and combined effects of food restriction and simulated microgravity on bone mass and serum leptin. Six-month-old male Sprague-Dawley rats were randomly assigned to four groups ( n = 12 each): two hindlimb-unloading (HU) groups fed 100% (HU100) and 70% (HU70) and two cage-activity control (CC) groups fed 100% (CC100) and 70% (CC70) of their baseline food requirement. After 28 days, CC100 rats gained body weight, whereas all other groups lost body weight; this loss was greater in HU70 than in CC70 and HU100 rats. Serum leptin decreased in CC70 and HU100 (−60% and −27%, respectively) and was not detectable in HU70 animals. Percent osteoid surface in CC70 and HU100 was lower than that of CC100 (7.80%, 8.60% vs. 10.70%, respectively), and this decrease was more pronounced in HU70 animals (4.38%). Mineral apposition rate of CC70, HU100, and HU70 rats was lower than that of CC100 (1.5, 1.6, and 1.5 vs. 2.1 μm/day, respectively). Bone formation rate of CC70, HU100, and HU70 rats was lower than that of CC100 (13.4, 13.1, and 12.2 vs. 40.8 mm3·mm−2·day−1, respectively). The change in bone formation rate was correlated with the change in serum leptin value over 28 days ( r2 = 0.69, P = 0.0007). We conclude that moderate caloric restriction may cause bone loss at susceptible bone sites to a similar degree as does the unloading effect of microgravity; serum leptin may be an important endocrine regulator contributing to this change in skeletal integrity.

Establishing a reference range for bone turnover markers in young, healthy women

INTRODUCTION

Biochemical markers of bone turnover (BTMs) are important in determining fracture risk in postmenopausal women; high levels being associated with increased risk. A proposed goal of anti-resorptive therapy is to reduce BTMs to the lower half of the reference range for healthy young pre-menopausal women. Our aims were a) to establish reference ranges for bone alkaline phosphatase (bone ALP), crosslinked C- and N-telopeptides of type I collagen (betaCTX, NTX), osteocalcin (OC) and procollagen type I N propeptide (PINP) in pre-menopausal women and b) to investigate the determinants of these BTMs.

METHODS

BTMs were measured in peripheral blood and second morning void urine collected from 200 healthy pre-menopausal women ages 30 to 45 years. Each subject completed a short medical and lifestyle questionnaire.

RESULTS

BTMs were higher before the age of 35 years than after it. BTMs were higher in women with low BMI (betaCTX and OC), low alcohol consumption (PINP), current smoking habit (bone ALP and NTX), and around time of ovulation (NTX).

CONCLUSIONS

We recommend that the age range 35 to 45 years should be used when establishing BTM reference ranges in women.

BMD decreases over the course of a year in competitive male cyclists

Male cyclists have been found to have low BMD in cross-sectional studies. Changes in BMD values over 1 yr of training and competition were studied in 14 male cyclists. BMD decreased significantly at the total hip, neck, trochanter, and shaft regions but not the lumbar spine. This first prospective study of cyclists showed a decrease in BMD over the course of 1 yr.

INTRODUCTION

Cross-sectional studies have shown that some endurance athletes, and cyclists in particular, have low BMD. Whether vigorous cycle training is causally related with low BMD remains unknown.

MATERIALS AND METHODS

Changes in BMD values over 1 yr of training and competition were studied in 14 male road cyclists, 27-44 yr of age. Subjects were randomized to receive 1500 (500 mg with meals) or 250 mg of supplemental calcium citrate daily. BMD measurements were obtained at pre-, mid-, post-, and off-season time points over 1 yr. Dermal calcium loss during exercise was estimated using a patch collection technique to examine calcium loss as a potential mediator of changes in BMD.

RESULTS

Using paired t-tests, BMD was found to decrease significantly from pre- to off-season at the total hip, neck, shaft, and trochanter regions (relative changes of -1.5 +/- 2.1%, -0.7 +/- 2.1%, -0.9 +/- 2.1%, and -1.0 +/- 1.2%, respectively, all p < 0.05). The 1.0 +/- 1.2% decrease in BMD at the lumbar spine failed to reach statistical significance (p = 0.079). There were no differences in changes in BMD between the calcium supplementation groups. The 2-h dermal calcium loss was estimated at 136.5 +/- 60.5 mg. Higher dermal calcium losses were associated with lower baseline BMD values at the total hip, neck, and shaft (all p < 0.05), but were not significantly associated with changes in BMD.

CONCLUSIONS

This study suggests that high intensity cycle training may adversely affect BMD. Excessive dermal calcium loss during exercise may be a contributing factor, but mechanisms remain to be elucidated.

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.

Mineral metabolism in obese patients following vertical banded gastroplasty

BACKGROUND

Bone disease has been described in patients after surgical treatment for obesity, but few studies have dealt with the impact of vertical banded gastroplasty on mineral metabolism. We have examined bone mineral metabolism in morbidly obese patients before and after 3 months after vertical banded gastroplasty without vitamin D supplementation.

METHODS

Sixteen morbidly obese patients (14 women, 2 men) with a mean (+/-SD) age of 38 +/- 9 years and a body mass index (BMI) of 47.1 +/- 8.1 kg/m2 were studied. No vitamin D supplementation was given. Body weight, fat mass, calcium, 25OHD, iPTH, bone remodeling markers, and leptin levels were measured at baseline and after weight loss.

RESULTS

Mean weight loss was 28 +/- 11 kg; BMI and body fat mass decreased by 20 and 35%, respectively. Bone resorption markers and albumin-corrected serum calcium increased after operation, whereas iPTH fell. Serum 25OHD levels rose. Leptin levels decreased. Serum iPTH was positively correlated with weight, BMI, and fat mass before operation (p < 0.05), and its decline after weight reduction was negatively associated with the increase in bone resorption markers (p < 0.01). Leptin concentration was correlated with BMI and body fat mass (p < 0.05) both before and after surgery.

CONCLUSIONS

Weight reduction obtained in morbidly obese subjects 3 months after vertical banded gastroplasty increases bone turnover markers and decreases PTH secretion. Serum 25OHD levels rose. Therefore, no reasons for a metabolic bone disease related to hypovitaminosis D were readily apparent. However, an increase in bone turnover, which is generally regarded as a potential risk factor for osteoporosis, was observed. Further work is needed to clarify the importance of this turnover increase in the long run.

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.

Effects of weight loss on bone status after bariatric surgery: association between adipokines and bone markers

BACKGROUND

The prevalence of overweight and obesity is increasing dramatically worldwide. As a consequence, bariatric surgery for morbid obesity is in constant development. Although bariatric surgery has proven its efficiency at achieving weight loss and correcting comorbidities, it may cause vitamin deficiencies and subsequent complications. The goal of this review is to assess the impact of obesity surgery on bone metabolism and to analyze the underlying mechanisms and relationships with adipokines. Our review focuses on gastric banding, vertical banded gastroplasty, and gastric bypass.

METHODS

The articles were located via PubMed database, using the key words "bariatric surgery," "weight loss," "bone loss," and "bone metabolism" and published until May 2006.

RESULTS

Five main studies were reviewed concerning gastric banding and six concerning Roux-en-Y gastric bypass. An early increase in bone markers (formation and resorption) is constantly found, prevailing on bone resorption, and resulting in early bone loss.

CONCLUSION

According to the few studies available, bone loss frequently occurs after bariatric surgery and particularly in a more pronounced way after gastric bypass, but its clinical significance is still under discussion. In addition, the physiopathology of these changes remains unclear, but could implicate adipokines such as leptin and adiponectin.

Effects of soy protein isolate and moderate exercise on bone turnover and bone mineral density in postmenopausal women

OBJECTIVE

The aim of this study was to assess the independent and additive effects of soy protein isolate (SPI) and moderate-intensity exercise (EX) on bone turnover and bone mineral density (BMD).

DESIGN

This study used a placebo-controlled, double-blind (soy), randomized 2 (SPI vs milk protein isolate [MPI]) x 2 (EX vs no EX) design. Sixty-one postmenopausal women were randomized, and 43 (62 +/- 5 y) completed the 9-month intervention (SPI, n = 10; MPI, n = 12; SPI + EX, n = 11; MPI + EX, n = 10). Serum C-terminal cross-linked telopeptides of type I collagen and serum bone-specific alkaline phosphatase were measured as markers of bone resorption and formation, respectively. BMD was measured by dual-energy x-ray absorptiometry.

RESULTS

At 9 months, SPI reduced serum C-terminal cross-linked telopeptides (-13.3% +/- 15.3% vs -1.5% +/- 21.0%; P = 0.02) and serum bone-specific alkaline phosphatase (-4.7% +/- 14.7% vs 6.5% +/- 17.7%; P = 0.02) compared to milk protein isolate. EX attenuated the reduction in serum C-terminal cross-linked telopeptides (-1.9% +/- 21.6% vs -12.4% +/- 15.3%; P = 0.04); however, no EX effects were apparent in serum bone-specific alkaline phosphatase at 9 months (2.8% +/- 16.1% vs -1.0% +/- 18.3%; P = 0.28). Neither SPI nor EX affected BMD at any site; however, change in BMD was related to change in fat mass (r = 0.40, P < 0.05).

CONCLUSIONS

In postmenopausal women (1) SPI reduces bone turnover with no impact on BMD over 9 months; (2) moderate-intensity endurance exercise training did not favorably alter bone turnover and had no impact on BMD; and (3) there were no additive effects of soy and exercise on bone turnover or BMD.

Premenopausal overweight women do not lose bone during moderate weight loss with adequate or higher calcium intake

BACKGROUND

Weight loss is associated with bone loss, but this has not been examined in overweight premenopausal women.

OBJECTIVE

The aim of this study was to assess whether overweight premenopausal women lose bone with moderate weight loss at recommended or higher than recommended calcium intakes.

DESIGN

Overweight premenopausal women [n = 44; x (+/-SD) age: 38 +/- 6.4 y; body mass index (BMI): 27.7 +/- 2.1 kg/m(2)] were randomly assigned to either a normal (1 g/d) or high (1.8 g/d) calcium intake during 6 mo of energy restriction [weight loss (WL) groups] or were recruited for weight maintenance at 1 g Ca/d intake. Regional bone mineral density and content were measured by dual-energy X-ray absorptiometry, and markers of bone turnover were measured before and after weight loss. True fractional calcium absorption (TFCA) was measured at baseline and during caloric restriction by using a dual-stable calcium isotope method.

RESULTS

The WL groups lost 7.2 +/- 3.3% of initial body weight. No significant decrease in BMD or rise in bone turnover was observed with weight loss at normal or high calcium intake. The group that consumed high calcium showed a strong relation (r = 0.71) between increased femoral neck bone mineral density and increased serum 25-hydroxyvitamin D. No significant effect of weight loss on TFCA was observed, and the total calcium absorbed was adequate at 238 +/- 81 and 310 +/- 91 mg/d for the normal- and high-calcium WL groups, respectively.

CONCLUSION

Overweight premenopausal women do not lose bone during weight loss at the recommended calcium intake, which may be explained by sufficient amounts of absorbed calcium.