Nettleton J A, Hegsted D M
J Nutr. 1977 Oct;107(10):1909-17. doi: 10.1093/jn/107.10.1909.
The complex relationship between protein intake and energy restriction was studied in acutely and chronically restricted adult rats. Rats were fed either 12 or 24 kcal/day from protein alone or protein plus carbohydrate from 3 to 16 days in one experiment. In another, groups were fed either 0.75 or 1.5 g lactalbumin/day in diets supplying 90%, 80% or 70% of the ad libitum energy intake for 8 or 104 days. Body composition and nitrogen of various tissues were determined. In experiment 1, feeding protein conserved tissue and body nitrogen as long as sufficient adipose stores were maintained, but thereafter had no advantage over lower protein intakes supplemented with carbohydrate. In experiment 2, all rats gained weight in proportion to energy intake. Protein level was protective of carcass nitrogen, water and liver nitrogen in both the short- and long-term at the 80% and 90% level of energy intake. Energy intake was more important than protein in conserving muscle nitrogen. Effects of energy and protein restriction are complex and dependent upon the total amount of protein and energy provided, body reserves and duration of restriction.
在急性和慢性限食的成年大鼠中研究了蛋白质摄入与能量限制之间的复杂关系。在一项实验中，从第3天到第16天，大鼠仅喂食蛋白质，每日摄入量分别为12千卡或24千卡，或者喂食蛋白质加碳水化合物。在另一项实验中，给几组大鼠喂食不同的日粮，日粮中乳白蛋白的含量分别为每日0.75克或1.5克，能量摄入量分别为自由采食时的90%、80%或70%，持续8天或104天。测定了各种组织的身体组成和氮含量。在实验1中，只要维持足够的脂肪储备，喂食蛋白质就能保留组织和身体中的氮，但此后与补充碳水化合物的低蛋白摄入量相比并无优势。在实验2中，所有大鼠的体重增加都与能量摄入量成比例。在能量摄入量为80%和90%时，蛋白质水平在短期和长期内对胴体氮、水和肝脏氮都有保护作用。在保留肌肉氮方面，能量摄入比蛋白质更重要。能量和蛋白质限制的影响是复杂的，取决于所提供的蛋白质和能量总量、身体储备以及限制的持续时间。
