Calorie restriction and bone health in young, overweight individuals.

Calorie restriction (CR) is promoted to increase longevity, yet this regimen could lead to bone loss and fracture and therefore affect quality of life. 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. 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. 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 nutrientdense diets have no deleterious effect on bone health.

热量限制（CR）被提倡用于延长寿命，然而这种养生法可能导致骨质流失和骨折，从而影响生活质量。 46名个体被随机分为4组，为期6个月：（1）健康饮食（对照组）；（2）从基线能量需求减少25%的热量限制（CR组）；（3）通过热量限制和增加有氧运动相结合产生25%的能量缺口（CR + EX组）；（4）低热量饮食（890千卡/天；目标是减重15%），之后维持体重（LCD组）。在基线和6个月后测量骨密度（全身和髋部，采用双能X线吸收法）以及血清骨标志物（骨特异性碱性磷酸酶、骨钙素、I型胶原交联C - 末端肽和I型胶原交联N - 末端肽）。 平均±标准误体重降低情况为：对照组 - 1.0% ± 1.1%，CR组 - 10.4% ± 0.9%，CR + EX组 - 10.0% ± 0.8%，LCD组 - 13.9% ± 0.7%。与对照组相比，所有组的全身或髋部骨密度均无任何变化。所有3个干预组的血清I型胶原交联C - 末端肽所反映的骨吸收均增加，LCD组变化最大（CR组为23% ± 10%；CR + EX组为22% ± 9%；LCD组为74% ± 16%，而对照组为4% ± 10%）。LCD组的血清I型胶原交联N - 末端肽水平也升高。关于骨形成，CR组的骨碱性磷酸酶水平降低（ - 23% ± 10%），但CR + EX组、LCD组和对照组无变化。 适度的热量限制，无论是否结合运动，在6个月内保持钙摄入，会使年轻成年人的身体成分发生较大变化，但不会导致明显的骨质流失。需要进行更长时间的研究并对骨结构进行评估，以确认营养丰富的热量限制饮食对骨骼健康没有有害影响。