最佳减肥法：低血糖指数饮食

A diet based on healthy carbohydrates─rather than a low-fat or low-carbohydrate diet─offers the best chance of keeping weight off without bringing unwanted side effects, a study published Tuesday in the Journal of the American Medical Association suggests.

《美国医学学会杂志》（Journal of the American Medical Association）6月26日刊登的一项研究报告指出，以健康碳水化合物为主的饮食──而非低脂或低碳水化合物饮食──能达到最佳的减肥效果，并且不会带来副作用。

Study participants following a low-glycemic-index diet, which is similar to a Mediterranean diet and focuses on fish, fruit, vegetables, nuts and whole grains, also saw improved cholesterol levels and other important markers that lower the risks of developing heart disease and diabetes. Such a diet might include minimally processed oatmeal, almonds, brown rice, beans and healthy fats like olive oil, among other foods.

研究发现，遵循低血糖指数饮食方案的研究对象的胆固醇水平及其他几项降低罹患心脏病和糖尿病风险的重要指标也有所改善。低血糖指数饮食与地中海式饮食相似，主要食用鱼类、水果、蔬菜、坚果和全谷物食品。该种饮食也可包括轻微加工过的燕麦片、杏仁、糙米、豆类和以橄榄油为代表的健康油脂等食物。

The study was led by researchers at the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital and funded by the National Institutes of Health and the New Balance Foundation, which is affiliated with the athletic-shoe maker. It was designed to assess how each of three common diets affects the ability to keep weight off. Participants had all of their food prepared for them, and their food intake was monitored. They ate many meals at the hospital, picking up others to eat at home.

这项研究由波士顿儿童医院（Boston Children's Hospital）新百伦基金肥胖预防中心（New Balance Foundation Obesity Prevention Center）的研究人员主导，由美国国立卫生研究院（National Institutes of Health）和运动鞋制造商新百伦旗下的新百伦基金会（New Balance Foundation）提供资助。研究旨在评估三种日常饮食方案对减肥效果的影响。研究对象只吃研究人员为其准备的食物，他们的进食过程也受到监控。他们有时在医院用餐，有时将食物带回家吃。

David Ludwig, one of the study's authors and the director of the center, explained that most people struggle to keep weight off. Previous studies have shown that weight loss reduces the body's daily energy expenditure─or how many calories the body burns through activity and just by resting─making it easy to regain weight. Dr. Ludwig's study was designed to look at the impact of the three diets on measures of energy expenditure, in addition to assessing hormones, fat levels in the blood and other health markers.

研究报告作者之一、肥胖预防中心主任大卫·路德维希（David Ludwig）解释说，大多数人都在费尽心机减肥。以往的研究已经证明，体重减轻会降低身体每日的能量支出──即身体通过活动或只是静止不动燃烧掉的卡路里──这样使得体重容易反弹。路德维希的研究旨在观察三种饮食方案对热量消耗量的影响，同时评估血液中的激素和脂肪水平以及其他的健康指标。

The study's 21 participants, 18 to 40 years old, initially lost 10% to 15% of their body weight during a three-month diet that contained about 45% of total calories from carbohydrates, 30% from fat and 25% from protein.

21名研究对象年龄在18到40岁之间。他们在最初的三个月里减掉了10%-15%的体重，这三个月里他们遵循的饮食方案中45%的热量来自碳水化合物，30%来自脂肪，还有25%来自蛋白质。

A month later, participants were placed on one of three diets for a month: a low-fat diet limiting fats to 20% of total calories; a low-carbohydrate diet modeled on the Atkins diet, limiting carbohydrate intake to 10% of total calories; and a low-glycemic-index diet, which contained 40% of total calories from carbohydrates, 40% from fats and 20% from protein. Participants were then switched to the other two diets during two additional four-week periods.

一个月后，他们分别开始遵循这三种饮食方案中的一种：低脂饮食，脂肪占总热量摄入的20%；阿特金斯饮食法（Atkins diet）的低碳水化合物饮食，碳水化合物的摄入量只占总热量摄入的10%；还有低血糖指数饮食，其中碳水化合物占总热量的40%，脂肪占40%，蛋白质占20%。四周后改为下一种饮食方案，再过四周改为第三种饮食方案。

'The low-fat diet had the worst effect' on energy expenditure, Dr. Ludwig said. Participants on that diet also had increases in triglycerides, a type of fat, and lower levels of so-called good cholesterol. 'We should avoid severely restricting any major nutrient and focus on the quality of the nutrient,' he said.

路德维希博士说，低脂饮食对增加能量支出的效果最差。遵循这种饮食方案的研究对象还出现了甘油三酯（一种脂肪）水平上升，所谓的有益胆固醇的水平也有所降低。他说，我们应当避免严格控制任何一种主要营养素，而应该注意保证营养素的质量。

Dr. Ludwig said those on the low-carb diet had the biggest boost in total energy expenditure, burning about 300 calories more per day than those on the low-fat diet─about the same as an hour of moderate exercise. But that bump came at a cost: increases in cortisol, a stress hormone, and a measure of inflammation called CRP, which can raise the risk of developing heart disease and diabetes.

路德维希博士说，遵循低碳水化合物饮食的研究对象总能量支出的增幅最大，每日消耗量比低脂饮食者多300卡路里左右──这几乎等于一小时中等强度运动所消耗掉的能量。然而如此突出的效果是有代价的：应激素皮质醇水平升高，此外还导致一种名为C反应蛋白（CRP）的炎症标志物水平升高，它会增加罹患心脏病和糖尿病的风险。

Those on the low-glycemic-index diet burned about 150 calories a day more than those on the low-fat diet without any negative impacts on cholesterol levels or various hormones, making it the ideal diet, Dr. Ludwig said. The glycemic index measures the impact of carbohydrates on blood-sugar levels.

路德维希博士说，低血糖指数饮食者的日消耗热量约比低脂饮食者多150卡路里，同时对胆固醇水平和各类激素水平没有任何消极影响，这使它成为理想的饮食结构。血糖指数衡量的是碳水化合物对血糖水平的影响。

A second study in the same medical journal showed that people in an 18-month weight-loss program that started with monthly meetings lost nearly as much weight as those in a much costlier program of the same duration with group sessions that initially met weekly. That study, led by researchers at the University of Pittsburgh, found that the monthly program cut about $600 off the cost of a $1,360 traditional weight-loss program with the weekly classes.Members of the group taking monthly classes were mailed the same material as those who attended classes weekly, and those who failed to meet weight-loss goals could get individual counseling by phone or in person.

该杂志刊登的另一项研究对两种减肥课程的效果进行了研究：两种课程均为期18个月，一种是每月上课一次，另一种花费更贵、每周进行小组讨论，结果发现参加两种课程的人减掉的体重相差无几。这项由匹兹堡大学（University of Pittsburgh）研究人员牵头的研究发现，每月减肥课程的成本比传统的每周减肥课程低600美元，后者花费为1,360美元。参加每月课程的成员收到的材料与参加每周课程的人相同，未能达到减肥目标者可以获得一对一的电话或面对面咨询。