INRA, UMR 1019 Nutrition Humaine, F-63122, Saint Genès Champanelle, France.
Obesity (Silver Spring). 2011 Jun;19(6):1137-44. doi: 10.1038/oby.2010.260. Epub 2010 Oct 21.
Severe energy restriction in obesity not only leads to fat mass loss but also to lean mass loss. The aim of this study was to compare the capacity of casein, a slowly digested protein, and milk soluble proteins (MSP; rapidly digested) to limit the loss of lean mass induced by energy restriction. Obesity was first induced in male Wistar rats by a 5-week feeding with a high-fat high-sucrose diet. The impact of energy restriction was then studied with high-protein (32%) diets containing either casein, MSP, or a 50/50 mixture of both proteins for 3 weeks (n = 10 per group). Food intake, body weight, nitrogen balance, creatinine, and 3-methyl-histidine excretion were measured during energy restriction. Then, tissue weights, plasma metabolic parameters (amino acids, glucose, insulin, cholesterol, triglycerides), and in vivo liver and extensor digitorum longus (EDL) muscle protein synthesis rates were measured in postabsorptive state at the end of the experimental period. Although significant differences relevant to protein metabolism were observed between groups (protein intake, plasma amino acid concentrations, fecal nitrogen excretion, muscle protein synthesis rates), week per week, there were no significant differences in nitrogen balance whatever the protein used. In conclusion, our results show that in young overweight energy restricted rats, using a high-protein diet, the nature of protein intake has no influence on body protein retention.
肥胖症患者的严格能量限制不仅会导致脂肪质量的损失，还会导致瘦体重的损失。本研究的目的是比较酪蛋白（一种消化缓慢的蛋白质）和乳清蛋白（MSP；消化迅速）的能力，以限制由能量限制引起的瘦体重损失。首先，通过用高脂肪高蔗糖饮食喂养 5 周，在雄性 Wistar 大鼠中诱导肥胖症。然后，用含有 32%蛋白质的高蛋白（32%）饮食对能量限制进行研究，其中包含酪蛋白、MSP 或两者的 50/50 混合物，为期 3 周（每组 10 只）。在能量限制期间测量食物摄入量、体重、氮平衡、肌酐和 3-甲基组氨酸排泄。然后，在实验结束时的吸收后状态下测量组织重量、血浆代谢参数（氨基酸、葡萄糖、胰岛素、胆固醇、甘油三酯）以及体内肝脏和伸趾长肌（EDL）肌肉蛋白质合成率。尽管在组间观察到与蛋白质代谢相关的显著差异（蛋白质摄入量、血浆氨基酸浓度、粪便氮排泄、肌肉蛋白质合成率），但无论使用何种蛋白质，氮平衡都没有差异。总之，我们的结果表明，在年轻超重的能量限制大鼠中，使用高蛋白饮食时，蛋白质摄入的性质对身体蛋白质保留没有影响。
