Martin Ashley A
Childhood Obesity Research Center, Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA.
Physiol Behav. 2016 Aug 1;162:120-9. doi: 10.1016/j.physbeh.2016.04.010. Epub 2016 Apr 10.
A striking feature of the modern food environment is the sheer amount of dietary choice available to the individual. In addition to an endless variety of highly palatable and energy dense foods, efforts to combat obesity have resulted in the production of several low- and reduced-calorie versions of these foods that are marketed to consumers. As a result, we are now confronted with a staggering amount of 'dietary variability'-the same food item can be obtained in a variety of different energy densities. This is a concern because evidence in rodents suggests that this kind of dietary variability can compromise one of the major cognitive determinants of food intake among non-human animals-flavor-nutrient satiety learning. Flavor-nutrient satiety learning enables animals to learn about the energy content or satiating quality of the foods they consume and adjust their intake to fit their energy needs. Notably, evidence suggests that dietary variability can disrupt this kind of learning, leading to overeating and weight gain. Here, I discuss the utility of flavor-nutrient satiety learning in human dietary behavior, highlighting certain features of the modern environment that can be disruptive to the acquisition of this kind of learning in humans. Special emphasis is placed on dietary variability, however I also highlight other aspects of the environment that can undermine this kind of learning, such as competition from other satiety-relevant cues (i.e., food labels), detrimental effects of Western diets on food-related cognitive processing, and the abundance of macronutrients that are inadequate at supporting learned satiety responses. The goal of this work is to highlight novel ways in which the environment may disrupt food-relevant learning and energy intake, and to provide some explanation for the elusive nature of flavor-nutrient learning in humans.
现代食物环境的一个显著特征是个人可获得的饮食选择数量之多。除了种类繁多、美味可口且能量密集的食物外，为对抗肥胖所做的努力还催生了这些食物的几种低热量和减少热量版本，并向消费者进行营销。结果，我们现在面临着数量惊人的“饮食变异性”——同一种食物可以有多种不同的能量密度。这令人担忧，因为啮齿动物的证据表明，这种饮食变异性会损害非人类动物食物摄入的主要认知决定因素之一——风味 - 营养饱腹感学习。风味 - 营养饱腹感学习使动物能够了解它们所食用食物的能量含量或饱腹感质量，并调整摄入量以满足其能量需求。值得注意的是，有证据表明饮食变异性会扰乱这种学习，导致暴饮暴食和体重增加。在此，我讨论风味 - 营养饱腹感学习在人类饮食行为中的作用，强调现代环境中可能干扰人类获得这种学习的某些特征。特别强调饮食变异性，但我也强调环境中可能破坏这种学习的其他方面，例如来自其他与饱腹感相关线索（即食品标签）的竞争、西方饮食对与食物相关认知加工的有害影响，以及大量宏量营养素不足以支持习得的饱腹感反应。这项工作的目标是突出环境可能扰乱与食物相关学习和能量摄入的新方式，并为人类风味 - 营养学习难以捉摸的本质提供一些解释。
