Associations among endocrine, inflammatory, and bone markers, body composition and weight loss induced bone loss.
BACKGROUND
Weight loss reduces co-morbidities of obesity, but decreases bone mass.


OBJECTIVE
Our aims were to (1) determine if adequate dairy intake attenuates weight loss-induced bone loss; (2) evaluate the associations of endocrine, inflammatory and bone markers, anthropometric and other parameters to bone mineral density and content (BMD, BMC) pre- and post-weight loss; and (3) model the contribution of these variables to post weight-loss BMD and BMC.


METHODS
Overweight/obese women (BMI: 28-37 kg/m2) were enrolled in an energy reduced (-500 kcal/d; -2092 kJ/d) diet with adequate dairy (AD: 3-4 servings/d; n=25, 32.2±8.8 years) or low dairy (LD: ≤1 serving/d; n=26, 31.7±8.4 years). BMD, BMC and body composition were measured by DXA. Bone markers (CTX, PYD, BAP, OC), endocrine (PTH, vitamin D, leptin, adiponectin, ghrelin, amylin, insulin, GLP-1, PAI-1, HOMA) and inflammatory markers (CRP, IL1-β, IL-6, IL-8, TNF-α, cortisol) were measured in serum or plasma. PA was assessed by accelerometry.


RESULTS
Following weight loss, AD intake resulted in significantly greater (p=0.004) lumbar spine BMD and serum osteocalcin (p=0.004) concentration compared to LD. Pre- and post-body fat was negatively associated with hip and lumbar spine BMC (r=-0.28, p=0.04 to -0.45, p=0.001). Of note were the significant negative associations among bone markers and IL-1β, TNFα and CRP ranging from r = -0.29 (p=0.04) to r = -0.34 (p=0.01); magnitude of associations did not change with weight loss. Adiponectin was negatively related to change in osteocalcin. Factor analysis resulted in 8 pre- and post-weight loss factors. Pre-weight loss factors accounted for 13.7% of the total variance in pre-weight loss hip BMD; post-weight loss factors explained 19.6% of the total variance in post-weight loss hip BMD. None of the factors contributed to the variance in lumbar spine BMD.


CONCLUSIONS
AD during weight loss resulted in higher lumbar spine BMD and osteocalcin compared to LD. Significant negative associations were observed between bone and inflammatory markers suggesting that inflammation suppresses bone metabolism. Using factor analysis, 19.6% of total variance in post-weight loss hip BMD could be explained by endocrine, immune, and anthropometric variables, but not lumbar spine BMD.
AgroParisTech, Paris Institute of Science and Technology, for Life, Food and Environmental Sciences, Paris, France.
Marie A
MA
Labouesse
Obesity & Metabolism Research Unit, USDA, ARS, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA, USA.
Erik R
ER
Gertz
Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Brian D
BD
Piccolo
Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Elaine C
EC
Souza
Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Gertrud U
GU
Schuster
Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Megan G
MG
Witbracht
Analytical Support Laboratory, USDA, ARS, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA, USA.
Leslie R
LR
Woodhouse
Obesity & Metabolism Research Unit, USDA, ARS, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA, USA; Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Sean H
SH
Adams
Obesity & Metabolism Research Unit, USDA, ARS, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA, USA; Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA.
Nancy L
NL
Keim
Obesity & Metabolism Research Unit, USDA, ARS, Western Human Nutrition Research Center, 430 West Health Sciences Drive, Davis, CA, USA; Department of Nutrition, University of California, Davis, 1 Shields Avenue, Davis, CA, USA. Electronic address: marta.vanloan@ars.usda.gov.
Marta D
MD
Van Loan
D015502:Absorptiometry, Photon; D000328:Adult; D015415:Biomarkers / Q000378:metabolism*; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D006728:Hormones / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology*; D015431:Weight Loss
D015415:Biomarkers; D006728:Hormones
Body composition; Endocrine and inflammatory markers; Physical activity; Weight loss induced bone loss