title: 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.
abstract: 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.
authors.affiliation: Department of Nutritional Sciences, University of Missouri, Columbia, MO 65211, USA. hintonp@missouri.edu
authors.forename: P S
authors.initials: PS
authors.lastname: Hinton
authors.forename: R Scott
authors.initials: RS
authors.lastname: Rector
authors.forename: J E
authors.initials: JE
authors.lastname: Donnelly
authors.forename: B K
authors.initials: BK
authors.lastname: Smith
authors.forename: B
authors.initials: B
authors.lastname: Bailey
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001835:Body Weight / Q000502:physiology; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage*; D031204:Caloric Restriction; D003611:Dairy Products; D004038:Diet, Reducing; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D018673:Nutrition Policy; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood; D012737:Sex Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage; D015431:Weight Loss / Q000502:physiology*
chemical_list: D002136:Calcium, Dietary; D004044:Dietary Proteins; D010281:Parathyroid Hormone; D014807:Vitamin D