A modest increase in protein content and a modest decrease in glycemic index values allowed study subjects to maintain a 10-kg weight loss better than did other dietary manipulations, according to a randomized trial reported in the Nov. 25 issue of the New England Journal of Medicine.

More subjects also were able to continue losing weight while consuming this combination of high-protein, low-glycemic-index foods, said Thomas Meinert Larsen, Ph.D., of the University of Copenhagen and his associates in the Diet, Obesity, and Genes (Diogenes) study.

The Diogenes study was designed to assess the efficacy of five different maintenance diets in preventing weight regain after obese subjects lost at least 8% of their body weight during an 8-week low-calorie diet. The maintenance diets all contained moderate amounts of fats (25%-30% of total energy consumed), all allowed unrestricted caloric intake, and all attempted to keep alcohol and fiber contents comparable, varying only in their protein content and glycemic indexes.

The study was conducted at research centers throughout Europe. A total of 773 subjects who achieved their target weight loss during the low-calorie-diet period were randomly assigned to continue a 26-week maintenance phase following a diet low in protein (13% of total energy consumed) with a low glycemic index; a diet low in protein with a high glycemic index; a diet high in protein (25% of total energy consumed) with a low glycemic index; a high-protein, high-glycemic index diet; or a control diet with moderate protein content and no guidelines regarding glycemic index (N. Engl. J. Med. 2010;363:2102-13).

The study subjects received dietary counseling every other week for 6 weeks, and then monthly thereafter. They were given recipes, cooking instructions, behavioral advice, and a teaching system to help them achieve the targeted composition of macronutrients. Periodically, they weighed their food and completed food diaries for 3 consecutive days to facilitate monitoring of adherence. Adherence declined in all groups toward the end of the study.

A total of 29% of the subjects dropped out of the study during this 6-month maintenance phase, a rate nearly 10% higher than expected. Nevertheless, the Diogenes participants “were probably a more adherent group than participants in other studies, since they had adhered sufficiently to the low-calorie diet for 8 weeks to lose at least 8% of their body weight,” Dr. Larsen and his colleagues said.

“Despite issues of adherence, we believe that our results are generalizable to obese people, particularly if diets are facilitated by easy access to low-glycemic-index foods and a culture that supports these dietary changes,” they added.

Weight regain was significantly higher in the low-protein groups and the high-glycemic-index groups. In contrast, both the high-protein and low-glycemic-index groups were more likely to maintain their weight loss and to lose an additional 5% of their body weight.

Only subjects assigned to the group with low-protein content and high glycemic index showed significant weight regain – a mean of almost 2 kg.

The study subjects reported no between-group differences in feelings of satiety, “though we suspect that the effects were too subtle to be subjectively perceived or measured with the use of visual analog scales,” Dr. Larsen and his associates said.

The main limitation of this study was the relatively short duration of follow-up, said Dr. David S. Ludwig and Cara B. Ebbeling, Ph.D., in an editorial comment accompanying the article.

“A 2-kg difference in body weight, by itself, has limited practical implications.

“But a diet that could effectively prevent weight regain over the long term would have major public health significance. In this regard, the 12-month and longer follow-up data will be informative,” noted Dr. Ludwig and Dr. Ebbeling of the Optimal Weight for Life Program at Children’s Hospital and in the department of pediatrics at Harvard Medical School, both in Boston (N. Engl. J. Med. 2010;363:2159-61).

These findings show that “even a modest increase in dietary protein or a modest reduction in glycemic-index values was sufficient to minimize weight regain and promote further weight loss in obese patients after a successful weight-loss diet,” Dr. Larsen and his associates concluded.

At press time, author disclosures were not available.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

据11月25日版的《新英格兰医学杂志》中报道的一项随机试验，饮食中适度增加蛋白质含量、适度降低血糖指数维持体重减轻10 kg的效果优于其他饮食疗法。

本研究名为饮食、肥胖与基因研究(Diet, Obesity, and Genes study, Diogenes)，是在欧洲研究中心进行的，由哥本哈根大学的Thomas Meinert Larsen博士带领完成，目的是在经过8周低热量饮食后体重至少减轻8%的肥胖患者中评价5种不同的维持饮食防止体重再增加的效果。这5种维持饮食中均含有适量脂肪(占能量摄入总量的25%~30%)，均不限制热量的摄入，酒精和纤维素的含量彼此相当，只是蛋白质含量和血糖指数不同。

在本研究中，共有773名受试者在低热量饮食期间达到体重减轻目标，随后进入26周的维持期并被随机分配至低蛋白(占摄入总能量的13%)、低血糖指数饮食组，低蛋白、高血糖指数饮食组，高蛋白(占能量摄入总量的25%)、低血糖指数饮食组，高蛋白、高血糖指数饮食组或蛋白质含量适中、血糖指数不限的饮食组(N. Engl. J. Med. 2010;363:2102-13)。另外，受试者每隔1周接受1次饮食咨询，持续6周，此后改为每月1次。研究者为其提供食谱、烹饪指导、行为建议以及有助于其实现大量营养素摄入目标的教学系统。受试者还定期进行历时3天的饮食评估并完成相应的食物日记，以便于监测其依从性。研究结束时各组受试者的依从性均下降。在这6个月的维持期中，共有29%的受试者退出研究，比预期高出近10%。

试验结果显示，低蛋白饮食组和高血糖指数饮食组受试者的体重再增加率明显偏高。相比之下，高蛋白饮食组和低血糖指数饮食组受试者维持体重减轻的几率较高，并额外减轻了5%的体重。只有低蛋白、高血糖指数饮食组的受试者体重再增加明显——平均增加约2 kg。受试者的饱腹感无组间差异。

研究表明，即使是膳食蛋白质含量适度增加或血糖指数适度下降，也足以使肥胖患者在摄入减重饮食取得成功后的体重再增加达到最小，并可促进体重进一步减轻。

本研究的主要局限性为随访期较短。

截止发稿时仍未获得作者们的披露内容 。

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