Ebbeling Cara B, Leidig Michael M, Feldman Henry A, Lovesky Margaret M, Ludwig David S
Department of Medicine, Children's Hospital Boston, Boston, Mass 02115, USA.
JAMA. 2007 May 16;297(19):2092-102. doi: 10.1001/jama.297.19.2092.
The results of clinical trials involving diet in the treatment of obesity have been inconsistent, possibly due to inherent physiological differences among study participants.
To determine whether insulin secretion affects weight loss with 2 popular diets.
DESIGN, SETTING, AND PARTICIPANTS: Randomized trial of obese young adults (aged 18-35 years; n = 73) conducted from September 2004 to December 2006 in Boston, Mass, and consisting of a 6-month intensive intervention period and a 12-month follow-up period. Serum insulin concentration at 30 minutes after a 75-g dose of oral glucose was determined at baseline as a measure of insulin secretion. Outcomes were assessed at 6, 12, and 18 months. Missing data were imputed conservatively.
A low-glycemic load (40% carbohydrate and 35% fat) vs low-fat (55% carbohydrate and 20% fat) diet.
Body weight, body fat percentage determined by dual-energy x-ray absorptiometry, and cardiovascular disease risk factors.
Change in body weight and body fat percentage did not differ between the diet groups overall. However, insulin concentration at 30 minutes after a dose of oral glucose was an effect modifier (group x time x insulin concentration at 30 minutes: P = .02 for body weight and P = .01 for body fat percentage). For those with insulin concentration at 30 minutes above the median (57.5 microIU/mL; n = 28), the low-glycemic load diet produced a greater decrease in weight (-5.8 vs -1.2 kg; P = .004) and body fat percentage (-2.6% vs -0.9%; P = .03) than the low-fat diet at 18 months. There were no significant differences in these end points between diet groups for those with insulin concentration at 30 minutes below the median level (n = 28). Insulin concentration at 30 minutes after a dose of oral glucose was not a significant effect modifier for cardiovascular disease risk factors. In the full cohort, plasma high-density lipoprotein cholesterol and triglyceride concentrations improved more on the low-glycemic load diet, whereas low-density lipoprotein cholesterol concentration improved more on the low-fat diet.
Variability in dietary weight loss trials may be partially attributable to differences in hormonal response. Reducing glycemic load may be especially important to achieve weight loss among individuals with high insulin secretion. Regardless of insulin secretion, a low-glycemic load diet has beneficial effects on high-density lipoprotein cholesterol and triglyceride concentrations but not on low-density lipoprotein cholesterol concentration.
clinicaltrials.gov Identifier: NCT00130299.
涉及饮食治疗肥胖症的临床试验结果并不一致，这可能是由于研究参与者之间存在固有的生理差异。
确定胰岛素分泌是否会影响两种流行饮食方式下的体重减轻情况。
设计、地点和参与者：2004年9月至2006年12月在马萨诸塞州波士顿对肥胖的年轻成年人（18 - 35岁；n = 73）进行的随机试验，包括为期6个月的强化干预期和为期12个月的随访期。在基线时测定口服75克葡萄糖后30分钟的血清胰岛素浓度，作为胰岛素分泌的指标。在6个月、12个月和18个月时评估结果。对缺失数据进行保守估算。
低血糖负荷饮食（碳水化合物占40%，脂肪占35%）与低脂饮食（碳水化合物占55%，脂肪占20%）。
体重、通过双能X线吸收法测定的体脂百分比以及心血管疾病风险因素。
总体而言，饮食组之间的体重和体脂百分比变化没有差异。然而，口服葡萄糖后30分钟的胰岛素浓度是一个效应修饰因素（组×时间×口服葡萄糖后30分钟的胰岛素浓度：体重方面P = 0.02，体脂百分比方面P = 0.01）。对于口服葡萄糖后30分钟胰岛素浓度高于中位数（57.5微国际单位/毫升；n = 28）的人，在18个月时，低血糖负荷饮食比低脂饮食导致体重下降幅度更大（-5.8对-1.2千克；P = 0.004），体脂百分比下降幅度更大（-2.6%对-0.9%；P = 0.03）。对于口服葡萄糖后30分钟胰岛素浓度低于中位数水平的人（n = 28），饮食组在这些终点指标上没有显著差异。口服葡萄糖后30分钟的胰岛素浓度对心血管疾病风险因素不是一个显著修饰因素。在整个队列中，血浆高密度脂蛋白胆固醇和甘油三酯浓度在低血糖负荷饮食下改善得更多，而低密度脂蛋白胆固醇浓度在低脂饮食下改善得更多。
饮食减肥试验中的变异性可能部分归因于激素反应差异。对于胰岛素分泌高的个体，降低血糖负荷对于实现体重减轻可能尤为重要。无论胰岛素分泌情况如何，低血糖负荷饮食对高密度脂蛋白胆固醇和甘油三酯浓度有有益影响，但对低密度脂蛋白胆固醇浓度没有影响。
clinicaltrials.gov标识符：NCT00130299。
