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The study is worth a closer look to see what it did and did not prove.

这项研究值得我们去细究它证明了什么，没有证明什么。

Researchers at Stanford University took more than 600 people (which is huge for a nutrition study) aged 18 to 50 who had a body mass index of 28 to 40 (25-30 is overweight, and 30 and over is obese). The study subjects had to be otherwise healthy. They couldn’t even be on statins, or drugs for Type 2 diabetes or hypertension, which might affect weight or energy expenditure. They were all randomly assigned to a healthful low-fat or a healthful low-carbohydrate diet, and they were clearly not blinded to which group they were in.

斯坦福大学(Stanford University)的研究人员挑选了600多名(这个数字对营养学研究来说堪称巨大)年龄在18到50岁，身体质量指数在28到40之间(25到30之间为超重，30或以上为肥胖)的研究对象。他们在其他方面必须保持健康，甚至不能服用他汀类药物，也就是治疗2型糖尿病或高血压的药物。这些药物可能会影响体重或能量消耗。所有人被随机分到健康低脂饮食组或健康低碳水化合物饮食组， 他们显然 知道自己属于哪一个组。

All participants attended 22 instructional sessions over one year in groups of about 17 people. The sessions were held weekly at first and were then spaced out so that they were monthly in the last six months. Everyone was encouraged to reduce intake of the avoided nutrient to 20 grams per day over the first eight weeks, then participants slowly added fats or carbohydrates back to their diets until they reached the lowest level of intake they believed could be sustained for the long haul.

在一年时间里，所有参与者以大约17人一个小组的形式上了22次指导课。这些课程一开始每周一次，然后拉开间距，到最后六个月变成每月一次。在前八周，每个人都被鼓励将应避免的营养物质的摄入量降低到一天20克，然后参与者慢慢恢复各自饮食中的脂肪或碳水化合物摄入量，直到达到他们认为可以长期维持的最低摄入量。