BMJ：低肪饮食或是保持苗条身材、降低心血管疾病风险的关键

2012年12月8日 讯 /生物谷BIOON/ --近日，刊登在国际著名杂志BMJ上的一项研究报告中，世界卫生组织营养指导专家表示，低脂肪饮食是个人减肥以及保持苗条身材的关键。这项研究对于那些肥胖以及过重个体来说非常重要，肥胖或过重会增加个体患癌症、冠状动脉心脏病以及中风的风险。食物中总脂肪的减少和个体胆固醇水平降低以及血压降低直接相关，这也揭示了低脂肪饮食在预防心脏血管疾病风险上的有益作用。

这项研究包括了33项随机控制试验，研究包括了对来自北美、欧洲、新西兰的73，589个男性、女性以及儿童的研究信息。研究结果显示，低脂饮食可以降低个体体重1.6kg、BMI0.56kg/平方米以及降低腰围0.5cm。所有这些试验都指出，体重降低并不是最终的结果，体重的降低虽然容易，可是保持数年却非常困难。

研究者Lee Hooper说，我们在每一个临床试验中都发现，人们进行低脂饮食所表现出的体重降低具有明显的一致性，减少食用脂肪的人，其体重降低的更为明显。研究者重点研究了那些减少食用脂肪的人群，当然目的并不是降低体重，这些人群可以继续食用正常量的食物，结果证明了，其确实体重发生了降低，BMI也减小了，腰围也缩小了，而且这些人群可以保持身材长达数年。而且食物中脂肪量摄取的越少，体重降低地就越快。

研究者表示，降低饱和脂肪酸的摄入可以降低心脏疾病以及中风的风险，因此饮食中降低脂肪最为健康的方式就是降低饱和脂肪酸的摄取。保持健康并不只是关注脂肪和体重，通过降低脂肪摄入，尤其是饱和脂肪酸的摄入，是保持健康的开始；多进行运动、少吸烟、少饮酒、增加水果和蔬菜的摄入以及喝足量水对于我们保持健康都是必不可少的。

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Effect of reducing total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies.
OBJECTIVE
To investigate the relation between total fat intake and body weight in adults and children.
DESIGN
Systematic review and meta-analysis of randomised controlled trials and cohort studies.
DATA SOURCES
Medline, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials to June 2010.
INCLUSION CRITERIA
Randomised controlled trials and cohort studies of adults or children that compared lower versus usual total fat intake and assessed the effects on measures of body fatness (body weight, body mass index, or waist circumference) after at least six months (randomised controlled trials) or one year (in cohorts). Randomised controlled trials with any intention to reduce weight in participants or confounded by additional medical or lifestyle interventions were excluded.
DATA EXTRACTION
Data were extracted and validity was assessed independently and in duplicate. Random effects meta-analyses, subgroups, sensitivity analyses, and metaregression were done.
RESULTS
33 randomised controlled trials (73,589 participants) and 10 cohort studies were included, all from developed countries. Meta-analysis of data from the trials suggested that diets lower in total fat were associated with lower relative body weight (by 1.6 kg, 95% confidence interval -2.0 to -1.2 kg, I(2)=75%, 57,735 participants). Lower weight gain in the low fat arm compared with the control arm was consistent across trials, but the size of the effect varied. Metaregression suggested that greater reduction in total fat intake and lower baseline fat intake were associated with greater relative weight loss, explaining most of the heterogeneity. The significant effect of a low fat diet on weight was not lost in sensitivity analyses (including removing trials that expended greater time and attention on low fat groups). Lower total fat intake also led to lower body mass index (-0.51 kg/m(2), 95% confidence interval -0.76 to -0.26, nine trials, I(2)=77%) and waist circumference (by 0.3 cm, 95% confidence interval -0.58 to -0.02, 15,671 women, one trial). There was no suggestion of negative effects on other cardiovascular risk factors (lipid levels or blood pressure). GRADE assessment suggested high quality evidence for the relation between total fat intake and body weight in adults. Only one randomised controlled trial and three cohort studies were found in children and young people, but these confirmed a positive relation between total fat intake and weight gain.
CONCLUSIONS
There is high quality, consistent evidence that reduction of total fat intake has been achieved in large numbers of both healthy and at risk trial participants over many years. Lower total fat intake leads to small but statistically significant and clinically meaningful, sustained reductions in body weight in adults in studies with baseline fat intakes of 28-43% of energy intake and durations from six months to over eight years. Evidence supports a similar effect in children and young people.