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

Effects of Different Exercises Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis

BACKGROUND

Exercise and dietary interventions are essential for maintaining weight and reducing fat accumulation. With the growing popularity of various dietary strategies, evidence suggests that combining exercise with dietary interventions offers greater benefits than either approach alone. Consequently, this combined strategy has become a preferred method for many individuals aiming to maintain health. Calorie restriction, 5/2 intermittent fasting, time-restricted feeding, and the ketogenic diet are among the most popular dietary interventions today. Aerobic exercise, resistance training, and mixed exercise are the most widely practiced forms of physical activity. Exploring the best combinations of these approaches to determine which yields the most effective results is both meaningful and valuable. Despite this trend, a comparative analysis of the effects of different exercise and diet combinations is lacking. This study uses network meta-analysis to evaluate the impact of various combined interventions on body composition and to compare their efficacy.

METHODS

We systematically reviewed literature from database inception through May 2024, searching PubMed, Web of Science, Embase, and the Cochrane Library. The study was registered in PROSPERO under the title: "Effects of Exercise Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis" (identifier: CRD42024542184). Studies were meticulously selected based on specific inclusion and exclusion criteria (The included studies must be randomized controlled trials involving healthy adults aged 18 to 65 years. Articles were rigorously screened according to the specified inclusion and exclusion criteria.), and their risk of bias was assessed using the Cochrane risk of bias tool. Data were aggregated and analyzed using network meta-analysis, with intervention efficacy ranked by Surface Under the Cumulative Ranking (SUCRA) curves.

RESULTS

The network meta-analysis included 78 randomized controlled trials with 5219 participants, comparing the effects of four combined interventions: exercise with calorie restriction (CR+EX), exercise with time-restricted eating (TRF+EX), exercise with 5/2 intermittent fasting (5/2F+EX), and exercise with a ketogenic diet (KD+EX) on body composition. Intervention efficacy ranking was as follows: (1) Weight Reduction: CR+EX > KD+EX > TRF+EX > 5/2F+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.94 (-3.64, 9.52); 2.37 (-0.40, 5.15); 1.80 (-1.75, 5.34)). (2) BMI: CR+EX > KD+EX > 5/2F+EX > TRF+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 1.95 (-0.49, 4.39); 2.20 (1.08, 3.32); 1.23 (-0.26, 2.71)). (3) Body Fat Percentage: CR+EX > 5/2F+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.66 (-1.56, 6.89); 2.84 (0.56, 5.13); 3.14 (0.52, 5.75).). (4) Lean Body Mass in Male: CR+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of TRF+EX and KD+EX are -1.60 (-6.98, 3.78); -2.76 (-7.93, 2.40)). (5) Lean Body Mass in Female: TRF+EX > CR+EX > 5/2F+EX > KD+EX (Relative to TRF+EX, the effect sizes of CR+EX, 5/2F+EX and KD+EX are -0.52 (-2.58, 1.55); -1.83 (-4.71, 1.04); -2.46 (-5.69,0.76).).

CONCLUSION

Calorie restriction combined with exercise emerged as the most effective strategy for reducing weight and fat percentage while maintaining lean body mass. For women, combining exercise with time-restricted eating proved optimal for preserving muscle mass. While combining exercise with a ketogenic diet effectively reduces weight, it is comparatively less effective at decreasing fat percentage and preserving lean body mass. Hence, the ketogenic diet combined with exercise is considered suboptimal.

The effects of popular diets on bone health in the past decade: a narrative review

Bone health encompasses not only bone mineral density but also bone architecture and mechanical properties that can impact bone strength. While specific dietary interventions have been proposed to treat various diseases such as obesity and diabetes, their effects on bone health remain unclear. The aim of this review is to examine literature published in the past decade, summarize the effects of currently popular diets on bone health, elucidate underlying mechanisms, and provide solutions to neutralize the side effects. The diets discussed in this review include a ketogenic diet (KD), a Mediterranean diet (MD), caloric restriction (CR), a high-protein diet (HP), and intermittent fasting (IF). Although detrimental effects on bone health have been noticed in the KD and CR diets, it is still controversial, while the MD and HP diets have shown protective effects, and the effects of IF diets are still uncertain. The mechanism of these effects and the attenuation methods have gained attention and have been discussed in recent years: the KD diet interrupts energy balance and calcium metabolism, which reduces bone quality. Ginsenoside-Rb2, metformin, and simvastatin have been shown to attenuate bone loss during KD. The CR diet influences energy imbalance, glucocorticoid levels, and adipose tissue, causing bone loss. Adequate vitamin D and calcium supplementation and exercise training can attenuate these effects. The olive oil in the MD may be an effective component that protects bone health. HP diets also have components that protect bone health, but their mechanism requires further investigation. In IF, animal studies have shown detrimental effects on bone health, while human studies have not. Therefore, the effects of diets on bone health vary accordingly.

New Insights into Calorie Restriction Induced Bone Loss

Caloric restriction (CR) is now a popular lifestyle choice due to its ability in experimental animals to improve lifespan, reduce body weight, and lessen oxidative stress. However, more and more emerging evidence suggests this treatment requires careful consideration because of its detrimental effects on the skeletal system. Experimental and clinical studies show that CR can suppress bone growth and raise the risk of fracture, but the specific mechanisms are poorly understood. Reduced mechanical loading has long been thought to be the primary cause of weight loss-induced bone loss from calorie restriction. Despite fat loss in peripheral depots with calorie restriction, bone marrow adipose tissue (BMAT) increases, and this may play a significant role in this pathological process. Here, we update recent advances in our understanding of the effects of CR on the skeleton, the possible pathogenic role of BMAT in CR-induced bone loss, and some strategies to mitigate any potential side effects on the skeletal system.

Effects of 8-week High-Intensity Interval Training and Moderate-Intensity Continuous Training on Bone Metabolism in Sedentary Young Females

Objective

High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) have been reported as effective exercise modes on bone metabolism. However, very few studies focused on young women with sedentary behavior. The purpose of this study was to investigate the effects of 8-week HIIT on bone metabolism in sedentary young women.

Methods

26 healthy, sedentary female participants were randomly assigned to either the HIIT (n = 13, age 23.2 ± 2.9 yr, weight 59.2 ± 7.2 kg, height 162.9 ± 3.3 cm, body mass index 22.3 ± 2.7 kg/m²) or MICT (n = 13, age 21.9 ± 1.7 yr, weight 59.3 ± 6.6 kg, height 160.9 ± 4.4 cm, body mass index 21.6 ± 2.4 kg/m²) group. Both groups completed 8 weeks (3 sessions/week) of training on the treadmill, where the HIIT group were asked to complete 6 × 3-min bouts of running at the intensity of 80–90% maximum oxygen uptake (VO_2max) separated by 2-min active recovery at 30–40% VO_2max and the MICT group completed 30-min continuous running at the intensity of 60–70% VO_2max. The body composition, bone mineral density (BMD), calcaneus quantitative ultrasound, bone turnover markers, and lower limb muscle strength were measured pre and post interventions.

Results

After 8-week interventions, 1) The total body BMD (HIIT, +8.5%; MICT, +5.5%) significantly increased (p < 0.05) without difference between the two groups (p > 0.05). The calcaneus broadband ultrasound attenuation (CBUA) (HIIT, +16.0%; MICT, +4.6%) and calcaneus stiffness index (CSI) (HIIT, +16.7%; MICT, +2.5%) significantly increased in HIIT group (p < 0.05), but not in MICT group (p > 0.05). 2) The 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) (HIIT, +42.8%; MICT, +24.9%) level increased in both groups with significantly higher changes in HIIT (p < 0.05). 3) The score of standing long jump (HIIT, +10.3%; MICT, +3.8%) and vertical jump (HIIT, +5.3%; MICT, +2.0%) increased in both groups with significantly higher changes in HIIT (p < 0.05).

Conclusions

It suggested that 8-week HIIT and MICT interventions could improve bone metabolism. Compared with a similar workload of MICT, HIIT elicited superior benefits on bone metabolism.

Does exercise affect bone mineral density and content when added to a calorie-restricted diet? A systematic review and meta-analysis of controlled clinical trials

The effects of exercise in conjunction with weight-loss diets on bone health are mixed. Our objective was to systematically review and meta-analyze controlled clinical trials in adults investigating the addition of exercise to a weight-loss diet compared with a calorie-matched weight-loss diet without exercise on bone measures. Online databases including PubMed/MEDLINE, EMBASE, ISI (Web of Science), Scopus, and Google Scholar were searched up to April 2021 with no restriction. A random effects model was used to calculate the overall estimates. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Fourteen eligible controlled clinical trials were included in the systematic review. The meta-analysis revealed that, compared to weight-loss diets alone, the addition of exercise did not improve total body bone mineral density (BMD) [weighted mean difference (WMD) = 0.002 g/cm², P = 0.62, n = 8], lumbar BMD (WMD = 0.007 g/cm², P = 0.44, n = 9), total hip BMD (WMD = 0.015 g/cm², P = 0.14, n = 4) and total bone mineral content (BMC) (WMD =  - 11.97 g, P = 0.29, n = 7). Subgroup analysis revealed that resistance exercise in conjunction with hypocaloric diets positively affects total BMD compared to an energy restrictive diet alone (WMD = 0.01 g/cm², P = 0.003, n = 3). Overall, it appears that only resistance exercise beneficially affects total BMD during a calorie-restricted diet in adults. Further well-controlled and long-term clinical trials are still needed to confirm these results. PROSPERO registration number: CRD42020173434.

Bone Response to Weight Loss Following Bariatric Surgery

Obesity is a global health challenge that warrants effective treatments to avoid its multiple comorbidities. Bariatric surgery, a cornerstone treatment to control bodyweight excess and relieve the health-related burdens of obesity, can promote accelerated bone loss and affect skeletal strength, particularly after malabsorptive and mixed surgical procedures, and probably after restrictive surgeries. The increase in bone resorption markers occurs early and persist for up to 12 months or longer after bariatric surgery, while bone formation markers increase but to a lesser extent, suggesting a potential uncoupling process between resorption and formation. The skeletal response to bariatric surgery, as investigated by dual-energy X-ray absorptiometry (DXA), has shown significant loss in bone mineral density (BMD) at the hip with less consistent results for the lumbar spine. Supporting DXA studies, analyses by high-resolution peripheral quantitative computed tomography (HR-pQCT) showed lower cortical density and thickness, higher cortical porosity, and lower trabecular density and number for up to 5 years after bariatric surgery. These alterations translate into an increased risk of fall injury, which contributes to increase the fracture risk in patients who have been subjected to bariatric surgery procedures. As bone deterioration continues for years following bariatric surgery, the fracture risk does not seem to be dependent on acute weight loss but, rather, is a chronic condition with an increasing impact over time. Among the post-bariatric surgery mechanisms that have been claimed to act globally on bone health, there is evidence that micro- and macro-nutrient malabsorptive factors, mechanical unloading and changes in molecules partaking in the crosstalk between adipose tissue, bone and muscle may play a determining role. Given these circumstances, it is conceivable that bone health should be adequately investigated in candidates to bariatric surgery through bone-specific work-up and dedicated postsurgical follow-up. Specific protocols of nutrients supplementation, motor activity, structured rehabilitative programs and, when needed, targeted therapeutic strategies should be deemed as an integral part of post-bariatric surgery clinical support.

Exercise attenuates bone mineral density loss during diet-induced weight loss in adults with overweight and obesity: A systematic review and meta-analysis

BACKGROUND

Weight-loss-induced fat loss improves cardiometabolic health in individuals with overweight and obesity; however, weight loss can also result in bone loss and increased fracture risk. Weight-loss-induced bone loss may be attenuated with exercise. Our aim was to compare changes in bone mineral density (BMD) in adults with overweight and obesity who undertook diet-induced weight loss alone or in combination with exercise.

METHODS

We included randomized controlled trials (RCTs) in adults with overweight or obesity (aged ≥18 years; body mass index ≥25 kg/m2) that prescribed diet-induced weight loss alone or in combination with supervised exercise, and measured any bone structural parameters. Risk of bias was assessed using the Cochrane Risk of Bias tool. Random-effects meta-analyses determined mean changes and net mean differences (95% confidence intervals (95%CIs)) in the percentage of areal BMD (aBMD) change between groups.

RESULTS

We included 9 RCTs. Diet-induced weight loss led to significant losses in femoral neck aBMD (mean change: -1.73% (95%CI: -2.39% to -1.07%), p < 0.001) and total hip aBMD (-2.19% (95%CI: -3.84% to -0.54%), p = 0.009). Femoral neck aBMD losses were significantly greater in the diet-induced weight loss group compared to the exercise plus diet-induced weight loss group (net difference: -0.88% (95%CI: -1.73% to -0.03%)); however, there were no differences in aBMD changes at any other skeletal site: total hip (-1.96% (95%CI: -4.59% to 0.68%)) and lumbar spine (-0.48% (95%CI: -1.81% to 0.86%)). aBMD changes did not differ significantly according to exercise modality (resistance exercise, aerobic exercise, or a combination of the two) during diet-induced weight loss.

CONCLUSION

Diet-induced weight loss led to greater femoral neck bone loss compared to diet-induced weight loss plus exercise. Bone loss at the total hip and lumbar spine was not attenuated by exercise during diet-induced weight loss. The lack of consistent skeletal benefits may be due to the insufficient duration and/or training intensities of most exercise interventions. Additional RCTs with appropriate, targeted exercise interventions should be conducted.

Bone Mineral Density Changes during Weight Regain following Weight Loss with and without Exercise

The purpose of this study was to compare changes in bone mineral density (BMD) over a 6 month follow up (period of weight regain) in overweight, postmenopausal women having previously completed a 6 month weight loss (WL) intervention with and without aerobic exercise (AEX). Women (BMI > 25 kg/m²) underwent VO₂max and DEXA scans at baseline, after 6 months of WL or AEX + WL, and at 12 months ad libitum follow up. Both groups lost ~9% body weight from 0 to 6 months and regained ~2% from 6 to 12 months, while losing ~4% of appendicular lean mass (ALM) across the 12-month study duration. VO₂max increased 10% from 0 to 6 months and declined 12% from 6 to 12 months for AEX + WL, with no changes for WL. Total body (p < 0.01) and total femur (p = 0.03) BMD decreased similar between groups across time (combined groups: 0-6 months: total body: -1.2% and total femur: -1.2%; 6-12 months: total body: -0.26% and total femur: -0.09%). Less ALM loss and greater VO₂max increases during the WL phase were associated with attenuated BMD loss at various anatomical sites during periods of weight regain (6-12 months) p's < 0.05). Results suggest that BMD loss may continue following WL, despite weight regain. Further, this study adds to the literature by suggesting that preventing declines in muscle quality and function during WL may attenuate the loss of BMD during weight regain. Future studies are needed to identify mechanisms underlying WL-induced bone loss so that effective practices can be designed to minimize the loss of BMD during WL and weight maintenance in older women.

The Ability of Exercise to Mitigate Caloric Restriction-Induced Bone Loss in Older Adults: A Structured Review of RCTs and Narrative Review of Exercise-Induced Changes in Bone Biomarkers

Despite the adverse metabolic and functional consequences of obesity, caloric restriction- (CR) induced weight loss is often contra-indicated in older adults with obesity due to the accompanying loss of areal bone mineral density (aBMD) and subsequent increased risk of fracture. Several studies show a positive effect of exercise on aBMD among weight-stable older adults; however, data on the ability of exercise to mitigate bone loss secondary to CR are surprisingly equivocal. The purpose of this review is to provide a focused update of the randomized controlled trial literature assessing the efficacy of exercise as a countermeasure to CR-induced bone loss among older adults. Secondarily, we present data demonstrating the occurrence of exercise-induced changes in bone biomarkers, offering insight into why exercise is not more effective than observed in mitigating CR-induced bone loss.

Changes in bone mass associated with obesity and weight loss in humans: Applicability of animal models

The implications of obesity and weight loss for human bone health are not well understood. Although the bone changes associated with weight loss are similar in humans and rodents, that is not the case for obesity. In humans, obesity is generally associated with increased bone mass, an outcome which is exacerbated by advanced age and menopause. In rodents, by contrast, bone mass decreases in proportion to severity and duration of obesity, and is influenced by sex, age and mechanical load. Despite these discrepancies, rodents are frequently used to model the situation in humans. In this review, we summarise the existing knowledge of the effects of obesity and weight loss on bone mass in humans and rodents, focusing on the translatability of findings from animal models. We then describe how animal models should be used to broaden the understanding of the relationship between obesity, weight loss, and skeletal health in humans. Specifically, we highlight the aspects of study design that should be considered to optimise translatability of the rodent models of obesity and weight loss. Notably, the sex, age, and nutritional status of the animals should ideally match those of interest in humans. With these caveats in mind, and depending on the research question asked, our review underscores that animal models can provide valuable information for obesity and weight-management research.

Effect of a pulse-based diet and aerobic exercise on bone measures and body composition in women with polycystic ovary syndrome: A randomized controlled trial

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, with clinical symptoms including menstrual dysfunction and hyperandrogenemia, as well as insulin resistance which is thought to be a key contributing factor to symptoms. Insulin is also thought to positively affect bone while oligo- and amenorrhea are known to negatively affect bone. Lifestyle modification is the first recommendation to treat symptoms of PCOS; however, little is known about the effect of lifestyle interventions on bone measures in this population. Pulses (e.g., chickpeas, beans, split peas, lentils) have been shown to lower fasting insulin, and the objective of this study was to determine the effect of a pulse-based diet compared to the therapeutic lifestyle changes (TLC) diet on bone measures and body composition in women with PCOS. Women aged 18-35 years with PCOS were randomized to either a pulse-based diet or the TLC diet for 16-weeks while following an aerobic exercise program. Thirty-one in the TLC group and 29 in the pulse group completed dual-energy X-ray absorptiometry analysis following the intervention. After 16-weeks, both groups had a lower BMI, whole body fat mass, and % fat (p < 0.005), with no difference in lean mass. In both groups, lumbar spine bone mineral content (BMC) and density were higher following the intervention (p < 0.05) while femoral neck bone mineral density (BMD) was lower (p < 0.05). Intertrochanteric section modulus improved in both groups while there was a group x time interaction in femoral shaft subperiosteal width which was more favorable in the pulse group (p < 0.05). This study demonstrates that the femoral neck may be compromised during a lifestyle intervention in women with PCOS. Research is warranted to preserve bone health during lifestyle change in women with PCOS.

Beneficial impact of exercise on bone mass in individuals under calorie restriction: a systematic review and Meta-analysis of randomized clinical trials

Background: A major therapeutic goal in weight management should be total body fat reduction whereas as preserving lean body mass and bone mass density. It is uncertain if an exercise program reduces the adverse effects of calorie restriction-induced weight loss in adults.Objective: The aim of the present study was to evaluate the differences in bone mass between adults who enrolled in a calorie restriction or an exercise-calorie restriction induced weight loss program.Data sources: Both PubMed and Scopus libraries were searched up to February 2020.Methods: Systematic reviews and a meta-analysis were carried out of randomized clinical trials (published to February 2020) on differences in bone mineral density and content (BMD and BMC) of adults who lost weight by calorie restriction alone (CR) or exercise-calorie restriction (CR-E). The study quality was calculated using the Cochrane scoring system. Retrieved data were pooled when weight mean differences (WMDs) were computed between two groups for BMD and BMC at various sites of the body.Results: Thirteen studies, with a total of 852 participants were included. Available evidence found significantly higher BMD at the hip (WMD: 0.03 g/cm², 95%CI: 0.01 to 0.04, p < 0.001) and femoral neck WMD: 0.03 g/cm², 95%CI: 0.01 to 0.05, p < 0.001) and total body BMC (WMD: 0.13 kg/cm², 95%CI: -0.10 to 0.36, p < 0.001) in the CR-E compared to the CR weight loss group. In contrast, all changes in total body BMD (WMD: 0.00 g/cm², 95%CI: -0.01 to 0.02, p = 0.57) and lumbar spine BMD (WMD: 0.00 g/cm², 95%CI: -0.01 to 0.01, p = 0.89) were not statistically significant.Limitations: Little evidence was available for different sexes separately. Most individuals were postmenopausal females and no subgroup analysis could be conducted based on menopausal status.Conclusion: This study suggests that physical training can preserve and even significantly increase the bone mass of the hip and femoral neck during weight reduction. Of note, various exercise modalities affected BMD at different sites. Similar results were not found for lumbar spine and total body BMD.

Associations between Dietary Fiber Intake and Bone Mineral Density in Adult Korean Population: Analysis of National Health and Nutrition Examination Survey in 2011

Background

The correlations between the amount of daily fiber intake and bone mineral densities (BMDs) in Korean adult population were investigated in our study.

Methods

Utilizing the Korean National Health and Nutrition Examination Survey in 2011, multivariable linear regression was performed to explore the association between fiber consumption and BMD of lumbar vertebrae 1 to 4 (L1–4 total), L1, L2, L3, and L4 vertebrae, femur neck, femur total, and trochanter. All models were adjusted for age, body mass index, vitamin D level, smoking, physical activity, alcohol use, contraceptive use, hormonal replacement therapy, consumption of carbohydrate, protein, fat, calcium, phosphate, iron, thiamine, riboflavin, niacin, and vitamin C.

Results

In males aged between 18 and 45, fiber intake significantly increased BMDs of L1 (coefficient β=0.004, P=0.040) and L2 (β=0.004, P=0.038) while daily protein consumption significantly lowered BMDs of femur neck (β=−0.001, P=0.009), femur total (β=−0.001, P=0.008), and trochanter (β=−0.001, P=0.008). In males aged 65 and older, nutrient intake shows no significant correlations with BMDs except fat consumption was inversely associated with BMD of trochanter (β=−0.001, P=0.017). In females aged between 18 and 45, fiber intake shows no significant relationship with BMDs while daily fat consumption significantly increased BMDs of L1 (β=0.001, P=0.028), L2 (β=0.001, P=0.024), L3 (β=0.001, P=0.033), and L1–4 total (β=0.001, P=0.017).

Conclusions

Fiber intake was a protective factor of lumbar spine (L1 and L2) BMD in male aged between 18 and 45 but not in female participants of any age groups.

Effect of Exercise Modality During Weight Loss on Bone Health in Older Adults With Obesity and Cardiovascular Disease or Metabolic Syndrome: A Randomized Controlled Trial

The objective of this study was to determine the ability of either aerobic or resistance training to counter weight-loss-associated bone loss in older adults. There were 187 older adults (67 years, 70% women, 64% white) with obesity (BMI = 34.5 ± 3.7 kg/m² ) and cardiovascular disease and/or metabolic syndrome who were randomized to participate in an 18-month, community-based trial, with a follow-up assessment at 30 months. Intervention arms included: weight loss alone (WL; 7% to 10% baseline weight), WL plus aerobic training (WL + AT), and WL plus resistance training (WL + RT), as well as DXA-acquired total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD), and trabecular bone score (TBS). Biomarkers of bone turnover (procollagen type 1 N-terminal propeptide, C-terminal telopeptide of type 1 collagen) were measured at baseline, 6, 18, and 30 (aBMD and TBS only) months. CT-acquired hip and spine volumetric BMD (vBMD), cortical thickness, and bone strength were measured in a subset at baseline (n = 55) and 18 months. Total hip aBMD was reduced by 2% in all groups at 18 months, with a primary analysis showing no significant treatment effects for any DXA, biomarker, or CT outcome. After adjustment for WL and follow-up at 30 months, secondary analyses revealed that total hip [-0.018 (-0.023 to -0.012) g/cm² versus -0.025 (-0.031 to -0.019) g/cm² ; p = 0.05] and femoral neck [-0.01 (-0.009 to 0.008) g/cm² versus -0.011 (-0.020 to -0.002) g/cm² ; p = 0.06] aBMD estimates were modestly attenuated in the WL + RT group compared with the WL group. Additionally, lumbar spine aBMD was increased in the WL [0.015 (0.007 to 0.024) g/cm² ] and the WL + RT [0.009 (0.000 to 0.017) g/cm² ] groups compared with the WL + AT [-0.003 (-0.012 to 0.005)g/cm² ] group; both p ≤ 0.01. Community-based exercise does not prevent bone loss during active WL in older adults; however, adding RT may help minimize long-term hip bone loss. © 2018 American Society for Bone and Mineral Research.

Bone Health following Bariatric Surgery: Implications for Management Strategies to Attenuate Bone Loss

Bariatric surgery (BS) is an effective treatment for morbid obesity and its associated comorbidities. Following such a procedure, however, patients are at risk of developing metabolic bone disease owing to the combination of rapid weight loss, severely restricted dietary intake, and reduced intestinal nutrient absorption. Patients undergoing malabsorptive procedures are at a higher risk of postoperative bone health deterioration than those undergoing restrictive procedures; however, studies have demonstrated negative skeletal consequences of restrictive procedures as well. The clinical practice guidelines of some international associations have previously addressed preoperative evaluation and postoperative clinical care in order to maintain bone health in BS patients. Nevertheless, some issues regarding bone health in BS patients remain unclear owing to the lack of relevant randomized clinical trials, including doses of nutritional supplements pre- and post-BS. This review summarizes the current data regarding the skeletal consequences of BS and its mechanisms, with an emphasis on the preventive strategies and nutritional care that may be warranted in order to attenuate bone deterioration following BS.

Exercise during energy restriction mitigates bone loss but not alterations in estrogen status or metabolic hormones

Energy restriction causes bone loss, increasing stress fracture risk. The impact of exercise during energy restriction on bone and endocrine factors is examined. Exercise with energy restriction did not influence endocrine factors, but did mitigate some bone loss seen with energy restriction in sedentary rats.

INTRODUCTION

Chronic dietary energy restriction (ER) leads to bone loss and increased fracture risk. Strictly controlled trials of long-term ER with and without vigorous exercise are required to determine whether exercise loading can counterbalance ER-induced bone loss. The aim of this current project is to elucidate the impact of exercise and ER on bone mass, estrogen status, and metabolic hormones.

METHODS

Twenty-four virgin female Sprague-Dawley rats (n = 8/group) were divided into three groups-ad libitum fed + exercise (Adlib + EX), 40 % energy restricted + exercise (ER + EX), and 40 % energy restricted + sedentary (ER + SED). Energy availability between ER groups was equal. Treadmill running was performed 4 days/week at 70 % VO2max for 12 weeks.

RESULTS

Fat and lean mass and areal bone mineral density (aBMD) were lower after 12 weeks (p < 0.05) for ER + EX vs Adlib + EX, but ER + EX aBMD was higher than ER + SED (p < 0.0001). Serum leptin and a urinary estrogen metabolite, estrone-1-glucuronide (E1G), were lower at week 12 (p = 0.0002) with ER, with no impact of exercise. Serum insulin-like growth factor I (IGF-I) declined (p = 0.02) from baseline to week 12 in both ER groups. ER + EX exhibited higher cortical volumetric bone mineral density (vBMD) at the midshaft tibia (p = 0.006) vs ER + SED.

CONCLUSION

Exercise during ER mitigated some, but not all, of the bone loss observed in sedentary ER rats, but had little impact on changes in urinary E1G and serum IGF-I and leptin. These data highlight the importance of both adequate energy intake and the mechanical loading of exercise in maintaining bone mass.

The effects of weight loss approaches on bone mineral density in adults: a systematic review and meta-analysis of randomized controlled trials

We assessed the impact of weight loss strategies including calorie restriction and exercise training on BMD in adults using a systematic review of randomized controlled trials. Weight reduction results in reduced BMD at the hip, but has less effect on the spine. Both calorie restriction and a combination of calorie restriction and exercise result in a decrease in hip bone density, whereas weight loss response to exercise training without dietary restriction leads to increased hip BMD.

INTRODUCTION

Findings are not consistent on the effect of weight loss on bone mineral density (BMD). We conducted a systematic review on the randomized controlled trials to assess the effect of weight loss strategies, including calorie restriction and exercise programs on BMD in adults.

METHODS

A structured and comprehensive search of MEDLINE and EMBASE databases was undertaken up to March 2016. Study-specific mean differences (MD) were pooled using a random-effects model. Subgroup analysis and meta-regression were used to find possible sources of between-study heterogeneity.

RESULTS

Thirty-two randomized controlled trials met predetermined inclusion criteria. The meta-analysis revealed no significant difference on total BMD (MD 0.007, 95 % CI -0.020-0.034, p = 0.608). In contrast, the pooled data of studies showed a significant effect of weight loss on hip BMD (MD -0.008, 95 % CI -0.09 to -0.006 g/cm(2), p < 0.001) and also lumbar spine BMD (MD -0.018 g/cm(2), 95 % CI -0.019 to -0.017, p < 0.001). BMD in the hip site decreased after more than 4 months, especially in those who were obese. Moreover, calorie restriction interventions longer than 13 months showed a significant decreased in lumbar spine BMD.

CONCLUSION

Weight loss led to significant decreases at the hip and lumbar spine BMD but not at the total. Weight loss response following calorie restriction resulted in a decrease in hip and lumbar spine bone density especially more than 1 year; whereas an exercise-induced weight loss did not.

Does Diet-Induced Weight Loss Lead to Bone Loss in Overweight or Obese Adults? A Systematic Review and Meta-Analysis of Clinical Trials

Diet-induced weight loss has been suggested to be harmful to bone health. We conducted a systematic review and meta-analysis (using a random-effects model) to quantify the effect of diet-induced weight loss on bone. We included 41 publications involving overweight or obese but otherwise healthy adults who followed a dietary weight-loss intervention. The primary outcomes examined were changes from baseline in total hip, lumbar spine, and total body bone mineral density (BMD), as assessed by dual-energy X-ray absorptiometry (DXA). Secondary outcomes were markers of bone turnover. Diet-induced weight loss was associated with significant decreases of 0.010 to 0.015 g/cm(2) in total hip BMD for interventions of 6, 12, or 24 (but not 3) months' duration (95% confidence intervals [CIs], -0.014 to -0.005, -0.021 to -0.008, and -0.024 to -0.000 g/cm(2), at 6, 12, and 24 months, respectively). There was, however, no statistically significant effect of diet-induced weight loss on lumbar spine or whole-body BMD for interventions of 3 to 24 months' duration, except for a significant decrease in total body BMD (-0.011 g/cm(2); 95% CI, -0.018 to -0.003 g/cm(2)) after 6 months. Although no statistically significant changes occurred in serum concentrations of N-terminal propeptide of type I procollagen (P1NP), interventions of 2 or 3 months in duration (but not of 6, 12, or 24 months' duration) induced significant increases in serum concentrations of osteocalcin (0.26 nmol/L; 95% CI, 0.13 to 0.39 nmol/L), C-terminal telopeptide of type I collagen (CTX) (4.72 nmol/L; 95% CI, 2.12 to 7.30 nmol/L) or N-terminal telopeptide of type I collagen (NTX) (3.70 nmol/L; 95% CI, 0.90 to 6.50 nmol/L bone collagen equivalents [BCEs]), indicating an early effect of diet-induced weight loss to promote bone breakdown. These data show that in overweight and obese individuals, a single diet-induced weight-loss intervention induces a small decrease in total hip BMD, but not lumbar spine BMD. This decrease is small in comparison to known metabolic benefits of losing excess weight.

Muscle-bone and fat-bone interactions in regulating bone mass: do PTH and PTHrP play any role?

Metabolic bone disease occurs when there is a net loss in bone density. Osteoporosis, the most common metabolic bone disease, is a devastating problem and an increasingly major public health issue. A substantial body of evidence in the elderly population indicates that a relationship exists between the components of body weight and various measures of bone/mass, density, and function. Both muscle and fat contribute to the body's total weight and the intimate associations of muscle, fat, and bone are known. But the close functional interactions between muscle and bone or fat and bone are largely unidentified and have drawn much attention in recent years. Each of these tissues not only responds to afferent signals from traditional hormone systems and the central nervous systems but also secretes factors with important endocrine functions. Studies suggest that during growth, development, and aging, the relationship of muscle and fat with the skeleton possibly governs bone homeostasis and turnover. A better understanding of the endocrine function and the cellular and molecular mechanisms and pathways linking muscle or adipose tissues with bone anabolism and catabolism is a new avenue for novel pathways for anabolic drug discovery. These in turn will likely lead to more rational therapy toward increasingly prevalent disorders like osteoporosis. In this review, some of the recent works on the interaction of bone with muscle and fat are highlighted, and in so doing the role of parathyroid hormone (PTH), and PTH-related peptide (PTHrP) is surveyed.

The independent and combined effects of intensive weight loss and exercise training on bone mineral density in overweight and obese older adults with osteoarthritis

OBJECTIVE

To determine the effects of dietary-induced weight loss (D) and weight loss plus exercise (D + E) compared to exercise alone (E) on bone mineral density (BMD) in older adults with knee osteoarthritis (OA).

DESIGN

Data come from 284 older (66.0 ± 6.2 years), overweight/obese (body mass index (BMI) 33.4 ± 3.7 kg/m2), adults with knee OA enrolled in the Intensive Diet and Exercise for Arthritis (IDEA) study. Participants were randomized to 18 months of walking and strength training (E; n = 95), dietary-induced weight loss targeting 10% of baseline weight (D; n = 88) or a combination of the two (D + E; n = 101). Body weight and composition (DXA), regional BMD, were obtained at baseline and 18 months.

RESULTS

E, D, and D + E groups lost 1.3 ± 4.5 kg, 9.1 ± 8.6 kg and 10.4 ± 8.0 kg, respectively (P < 0.01). Significant treatment effects were observed for BMD in both hip and femoral neck regions, with the D and D + E groups showing similar relative losses compared to E (both P < 0.01). Despite reduced BMD, fewer overall participants had T-scores indicative of osteoporosis after intervention (9 at 18 months vs 10 at baseline). Within the D and D + E groups, changes in hip and femoral neck, but not spine, BMD correlated positively with changes in body weight (r = 0.21 and 0.54 respectively, both P ≤ 0.01).

CONCLUSIONS

Weight loss via an intensive dietary intervention, with or without exercise, results in bone loss at the hip and femoral neck in overweight and obese, older adults with OA. Although the exercise intervention did not attenuate weight loss-associated reductions in BMD, classification of osteoporosis and osteopenia remained unchanged.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00381290.