纽约（路透社卫生）2006-12-11－通过热量限制减肥的男女而又不运动会造成髋骨和脊柱的骨质丢失，增加骨质疏松和骨折的危险。一项研究表明，适当的运动加上热量限制饮食能够保护骨骼免受节食的负面影响。
“运动在自愿减轻体重的时候对骨丢失起到保护作用，”该研究的领导者Dennis T. Villareal医师告诉路透社，“因此，运动和热量限制相结合是非常重要的，这样才能获得体重减轻的益处和保护骨骼。”
来自St. Louis华盛顿大学医学院的Villarea和同事们研究体重减轻对骨丢失的效应，研究对象为30个妇女以及18个男子，平均年龄为57岁，对象为超重体型而不属于肥胖。一年时间里，19个受试者坚持热量限制饮食；19个受试者摄入平常热量但定期运动；10个受试者作为对照处理组，只接受健康的生活方式，只有两个受试者完成了长达一年的研究。12个月结束后，节食者平均减掉了18.1磅，运动者则减掉了14.8磅，对照组在体重上则没有显著的改变。
根据《内科学文献》报道，节食者下位脊柱和髋骨平均损失了2.2%的骨密度。相比之下，运动组和健康生活方式组的骨矿物质密度无显著变化。调查者表示运动时肌肉牵拉骨骼的动作被认为是引起骨骼产生“健康”劳损，刺激新骨的生长。当前的研究支持这种观点。
“重要的是热量限制并不认为是一件坏事，” Villareal表示，“因为它对降低疾病危险率有莫大好处，也是体重减轻的有效方法。而且，热量限制对抗衰老提供了真实可能性，这方面不是单单运动能够达到的效果。”但是，为了维持骨骼健康，“运动在减轻体重方案的重要组成部分，弥补热量限制对骨骼产生的不良反应。”
Dieting without exercise harms bone health
Reuters Health
Monday, December 11, 2006
By Megan Rauscher
NEW YORK (Reuters Health) - Men and women who lose weight through caloric restriction, without exercise, also lose bone at the hip and spine, increasing their risk for the bone-thinning disease osteoporosis and fractures, a study shows. Adding regular exercise to a calorie-restricted diet helps shield the bones from the harmful effects of dieting.
"Exercise protects against bone loss during voluntary weight loss," Dr. Dennis T. Villareal, who led the study, told Reuters Health. "Therefore, it would be important to combine calorie restriction and exercise to derive the benefits of weight loss and preserve bone."
Villareal, from Washington University School of Medicine in St. Louis, and colleagues studied the effects of weight loss on bone loss in 30 women and 18 men whose average age was 57 years. The study subjects were overweight but not obese.
For one year, 19 subjects stuck to a calorie-restricted diet; 19 ate their usual number of calories but engaged in regular exercise; and 10 in a comparison "control" group received healthy lifestyle tips only. All but two participants completed the yearlong study.
At the end of the 12 months, the dieters lost an average of 18.1 pounds, while the exercisers lost 14.8 pounds and those in the control group had no significant change in their weight.
As reported in the Archives of Internal Medicine, the dieters lost an average of 2.2 percent of bone density in the lower spine and at the hip. In contrast, there were no significant changes in bone mineral density in the exercise group or healthy lifestyle groups.
The action of muscles pulling on bones during exercise is thought to produce "healthy" strain on the skeleton that stimulates the production of new bone, the investigators note. The current study supports this line of thought.
"It's important that calorie restriction not be seen as a bad thing," Villareal said, "because it offers enormous benefits with respect to reducing disease risk and is effective for weight loss. Also, there is a real possibility that calorie restriction provides anti-aging benefits that cannot be achieved through exercise alone."
However, to maintain healthy bones, "exercise should be an important component of a weight loss program to offset adverse effects of calorie restriction on bone," the team concludes.
SOURCE: Archives of Internal Medicine, December 11/25, 2006.
http://www.nlm.nih.gov/medlineplus/news/fullstory_42412.html
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