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.


BACKGROUND
clinicaltrials.gov Identifier: NCT00099151.
Redman
Leanne M
LM
Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
Rood
Jennifer
J
Anton
Stephen D
SD
Champagne
Catherine
C
Smith
Steven R
SR
Ravussin
Eric
E
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
D015415:Biomarkers; D024042:Collagen Type I; D015675:Osteocalcin; D000469:Alkaline Phosphatase