Dulloo A G, Jacquet J, Girardier L
Department of Physiology, Faculty of Medicine, University of Geneva, Switzerland.
Int J Obes Relat Metab Disord. 1996 May;20(5):393-405.
To gain insights into the control systems underlying human variability in the regulation of body composition during weight recovery, as well as the disproportionate recovery of fat relative to lean tissue, the classical Minnesota Experiment conducted on 32 men subjected to long-term semi-starvation and refeeding was revisited with the following objectives: (1) to determine whether the control of energy-partitioning between lean and fat tissues during weight loss and weight recovery is an individual characteristic, and if a predictor can be statistically identified, (2) to determine whether the reduction in thermogenesis during weight loss persists during weight recovery, and underlies the disproportionate recovery of fat tissue and (3) to integrate the control of energy-partitioning and that of thermogenesis in order to explain the pattern of lean and fat tissue mobilisation and deposition during weight loss and weight recovery.
Individual data on body weight, body fat, fat-free-mass (FFM), and basal metabolic rate (BMR), assessed during the control baseline period (i.e. prior to weight loss), at the end of 24 weeks of semi-starvation, and at the end of a 12 week period of restricted refeeding, were used to calculate the following parameters: (i) a quantitative index of energy-partitioning, the P-ratio, defined as the proportion of body energy mobilised as protein during weight loss, or as the proportion of body energy deposited as protein during weight recovery, (ii) a quantitative index of changes in thermogenesis, defined as the change in BMR adjusted for FFM (or for both FFM and fat mass) and (iii) the degree of replenishment of fat and FFM compartments, defined as the recovery of body fat and FFM (during refeeding) as a percentage of that lost during semi-starvation.
This re-analysis indicates the following: (i) a large inter-individual variability in P-ratio during both weight loss and weight recovery, but for a given individual, the P-ratio during refeeding is strongly correlated with the P-ratio during semi-starvation, (ii) body composition during the control period is the most important predictor of variability in P-ratio, such that the higher the initial % body fat, the lower the proportion of energy mobilised as protein, and hence the greater the propensity to mobilise fat during semi-starvation and to subsequently deposit fat during refeeding and (iii) at week 12 of refeeding, the change in adjusted BMR is found to be reduced by a magnitude which is inversely proportional to the degree of fat recovery, but is unrelated to the degree of FFM recovery. A quantitative relationship is derived between the P-ratio during refeeding, the % fat recovery, and the P-ratio during semi-starvation.
Evidence is presented here suggesting that (i) human variability in the pattern of lean and fat tissue deposition during weight recovery is to a large extent determined by individual variations in the control of energy-partitioning, for which the initial % body fat is the most important predictor and (ii) the disproportionate gain in fat relative to lean tissue during weight recovery is contributed by a reduction in thermogenesis (i.e. increased efficiency of food utilization) for accelerating specifically the replenishment of the fat stores. These control systems, operating via energy-partitioning and thermogenesis, have been integrated into a compartmental model for the regulation of body composition during underfeeding/refeeding, and can be used to explain the individual pattern of lean and fat tissue deposition during weight recovery in situations ranging from the rehabilitation after malnutrition to the relapse of obesity.
为深入了解体重恢复期间人体在身体成分调节方面潜在的控制系统，以及脂肪相对于瘦组织不成比例的恢复情况，我们重新审视了对32名长期处于半饥饿和再喂养状态的男性进行的经典明尼苏达实验，其目标如下：（1）确定在体重减轻和体重恢复期间，瘦组织和脂肪组织之间能量分配的控制是否是个体特征，以及是否能从统计学上确定一个预测指标；（2）确定体重减轻期间产热的降低在体重恢复期间是否持续存在，并是否是脂肪组织不成比例恢复的原因；（3）整合能量分配控制和产热控制，以解释体重减轻和体重恢复期间瘦组织和脂肪组织动员与沉积的模式。
利用在对照基线期（即体重减轻前）、半饥饿24周结束时以及限制再喂养12周结束时评估的个体体重、体脂、去脂体重（FFM）和基础代谢率（BMR）数据，计算以下参数：（i）能量分配的定量指标，即P比值，定义为体重减轻期间作为蛋白质动员的身体能量比例，或体重恢复期间作为蛋白质沉积的身体能量比例；（ii）产热变化的定量指标，定义为根据FFM（或根据FFM和脂肪量两者）调整后的BMR变化；（iii）脂肪和FFM区室的补充程度，定义为再喂养期间身体脂肪和FFM的恢复量占半饥饿期间损失量的百分比。
本次重新分析表明：（i）在体重减轻和体重恢复期间，P比值存在较大的个体间差异，但对于给定个体，再喂养期间的P比值与半饥饿期间的P比值密切相关；（ii）对照期的身体成分是P比值变异性的最重要预测指标，即初始体脂百分比越高，作为蛋白质动员的能量比例越低，因此在半饥饿期间动员脂肪以及随后在再喂养期间沉积脂肪的倾向就越大；（iii）在再喂养第12周时，发现调整后的BMR变化幅度减小，其减小幅度与脂肪恢复程度成反比，但与FFM恢复程度无关。得出了再喂养期间的P比值、脂肪恢复百分比和半饥饿期间的P比值之间的定量关系。
此处提供的证据表明：（i）体重恢复期间瘦组织和脂肪组织沉积模式的个体差异在很大程度上由能量分配控制的个体差异决定，其中初始体脂百分比是最重要的预测指标；（ii）体重恢复期间脂肪相对于瘦组织不成比例的增加是由于产热降低（即食物利用效率提高），从而加速了脂肪储备的补充。这些通过能量分配和产热起作用的控制系统已被整合到一个用于调节营养不良/再喂养期间身体成分的区室模型中，可用于解释从营养不良康复到肥胖复发等各种情况下体重恢复期间瘦组织和脂肪组织沉积的个体模式。
