School of Psychology, Faculty of Medicine and Health, University of Leeds, Leeds, UK.
Obes Rev. 2021 Mar;22 Suppl 2:e13191. doi: 10.1111/obr.13191. Epub 2021 Feb 1.
Understanding physiological and behavioral responses to energy imbalances is important for the management of overweight/obesity and undernutrition. Changes in body composition and physiological functions associated with energy imbalances provide the structural and functional context in which to consider psychological and behavioral responses. Compensatory changes in physiology and behavior are more pronounced in response to negative than positive energy balances. The physiological and psychological impact of weight loss (WL) occur on a continuum determined by (i) the degree of energy deficit (ED), (ii) its duration, (iii) body composition at the onset of the energy deficit, and (iv) the psychosocial environment in which it occurs. Therapeutic WL and famine/semistarvation both involve prolonged EDs, which are sometimes similar in magnitude. The key differences are that (i) the body mass index (BMI) of most famine victims is lower at the onset of the ED, (ii) therapeutic WL is intentional and (iii) famines are typically longer in duration (partly due to the voluntary nature of therapeutic WL and disengagement with WL interventions). The changes in psychological outcomes, motivation to eat, and energy intake in therapeutic WL are often modest (bearing in mind the nature of the measures used) and can be difficult to detect but are quantitatively significant over time. As WL progresses, these changes become more marked. It appears that extensive WL beyond 10%-20% in lean individuals has profound effects on body composition and physiological function. At this level of WL, there is a marked erosion of psychological functioning, which appears to run in parallel to WL. Psychological resources dwindle and become increasingly focused on alleviating escalating hunger and food seeking behavior. Functional changes in fat-free mass, characterized by catabolism of skeletal muscle and organs may be involved in the drive to eat associated with semistarvation. Higher levels of body fat mass may act as a buffer to protect fat-free mass, functional integrity and limit compensatory changes in energy balance behaviors. The increase in appetite that accompanies therapeutic WL appears to be very different to the intense and all-consuming drive to eat that occurs during prolonged semistarvation. The mechanisms may also differ but are not well understood, and longitudinal comparisons of the relationship between body structure, function, and behavior in response to differing EDs in those with higher and lower BMIs are currently lacking.
了解能量失衡对生理和行为的反应对于超重/肥胖和营养不良的管理很重要。与能量失衡相关的身体成分和生理功能的变化为考虑心理和行为反应提供了结构和功能背景。与正能平衡相比，负能平衡时生理和行为的代偿变化更为明显。体重减轻（WL）的生理和心理影响发生在一个连续体上，由以下因素决定：（i）能量不足（ED）的程度，（ii）其持续时间，（iii）ED 开始时的身体成分，以及（iv）发生的心理社会环境。治疗性 WL 和饥荒/半饥饿都涉及长时间的 ED，其大小有时相似。关键区别在于：（i）大多数饥荒受害者的身体质量指数（BMI）在 ED 开始时较低，（ii）治疗性 WL 是有意的，（iii）饥荒通常持续时间更长（部分原因是治疗性 WL 的自愿性质和与 WL 干预措施的脱离）。治疗性 WL 中心理结果、进食动机和能量摄入的变化通常是适度的（考虑到所使用措施的性质），并且可能难以检测，但随着时间的推移具有定量意义。随着 WL 的进展，这些变化变得更加明显。似乎在瘦个体中超过 10%-20%的广泛 WL 对身体成分和生理功能有深远影响。在这种 WL 水平下，心理功能明显受损，似乎与 WL 平行。心理资源减少，并越来越集中在缓解不断加剧的饥饿和寻找食物的行为上。无脂肪质量的功能变化，表现为骨骼肌和器官的分解代谢，可能与半饥饿相关的进食驱动力有关。较高水平的体脂质量可能作为保护无脂肪质量、功能完整性和限制能量平衡行为代偿变化的缓冲器。伴随治疗性 WL 的食欲增加似乎与长时间半饥饿期间发生的强烈和全食驱动进食非常不同。其机制也可能不同，但目前尚不清楚，目前缺乏对 BMI 较高和较低的个体对不同 ED 做出的身体结构、功能和行为反应的关系进行纵向比较。
