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Calorie restriction and bone health in young, overweight individuals
Redman LM, Rood J, Anton SD, Champagne C, Smith SR, Ravussin E, for the Pennington Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE) Research Team
Archives of Internal Medicine 2008 Sep 22;168(17):1859-1866
clinical trial
6/10 [Eligibility criteria: No; Random allocation: Yes; Concealed allocation: Yes; Baseline comparability: Yes; Blind subjects: No; Blind therapists: No; Blind assessors: Yes; Adequate follow-up: No; Intention-to-treat analysis: No; Between-group comparisons: Yes; Point estimates and variability: Yes. Note: Eligibility criteria item does not contribute to total score] *This score has been confirmed*

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% versus 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. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00099151.

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