title: Calorie restriction and bone health in young, overweight individuals.
abstract: 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.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT00099151.
authors.affiliation: Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Redman
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rood
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Anton
authors.forename: Catherine
authors.initials: C
authors.lastname: Champagne
authors.forename: Steven R
authors.initials: SR
authors.lastname: Smith
authors.forename: Eric
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001823:Body Composition / Q000502:physiology; D001835:Body Weight; D015519:Bone Density; D001842:Bone and Bones / Q000502:physiology*; D031204:Caloric Restriction; D024042:Collagen Type I / Q000097:blood; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D015675:Osteocalcin / Q000097:blood; D050177:Overweight
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D015675:Osteocalcin; D000469:Alkaline Phosphatase