Appetite and energy balancing
Appetite and energy balancing
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DOI：
10.1016/j.physbeh.2016.03.038
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发表时间：
2016-10-01
影响因子：
2.9
通讯作者：
Brunstrom, Jeffrey M.
中科院分区：
文献类型：
--
作者：
Rogers, Peter J.;Brunstrom, Jeffrey M.
在关于饮食行为的公共和科学讨论中，食物摄入是由能量消耗引起的“饥饿”引起（或预期）的观点是显而易见的。相比之下，我们的论点是，饮食与短期能量消耗很大程度上无关。与全身能量储存相比，每餐的能量需求微不足道，即使错过一顿饭甚至几顿饭，身体组织的能量供应也能维持。复杂而精致的代谢机制确保了这种情况的发生，但代谢调节仅与能量摄入的控制松散地结合在一起。相反，需要控制食物摄入量，因为肠道容量有限，意味着处理膳食会带来重大的生理挑战，并可能阻碍其他活动。我们用一个简单的类比来说明能量（食物）摄入和能量消耗之间的关系：（1）浴缸中的水代表身体的能量含量，（2）平底锅中的水代表肠道中的食物，（3）浴缸通过平底锅注水。此外，(4)需要数小时来处理并将平底锅中的全部能量（常量营养素）含量传递到浴缸，以及(5)平底锅和浴缸都无法填充，代表对食欲（进食欲望）的负反馈。该模型与以下观察结果一致：能量摄入（一顿饭添加到平底锅/肠道的有限容量中）会急剧降低食欲，但能量消耗的急剧增加（从浴缸/身体的大量能量中除去能量）不会增加食欲。对饮食性肥胖大鼠能量摄入和体重增加动态的观察支持了与身体脂肪成比例的相对非常弱但长期的食欲负反馈的存在。 （我们在这里使用术语“食欲”，因为“饥饿”意味着能量消耗。）在我们的模型中，食欲是由食物的可及性以及预期和体验到的吃食物的乐趣所激发的。后者与食物奖励类似，主要由肠道的空虚状态和与食物的感官品质和宏量营养素价值相关的食物喜好以及个人的饮食史决定。重要的是，能量密度增加了价值，因为能量密集的食物的饱足感较低，而饱足感限制了进一步的摄入。也就是说，能量密集型食物通过（1）更具吸引力和（2）具有较低的饱足能力kJ/kJ来促进能量摄入，并且（1）部分是（2）的结果。能量存储适应盛宴和饥荒，其中包括与从事其他活动相比，获取和摄入食物的成本随时间的不均匀性。然而，在非常低成本的食品环境中，容易获得能量密集的食品，肥胖的风险很高。这种风险可以通过饮食限制来减轻，最简单的形式可能意味着偶尔不吃一餐。我们讨论的另一个策略是通过用低热量甜味剂代替饮食中的一些糖来实现能量稀释。然而，也许同样或更重要的是，对短期能量平衡（能量消耗模型）的信念可能会破坏少吃的尝试。因此，纠正饮食的叙述使其符合生物学现实也有助于控制体重。 (C) 2016 年作者。由爱思唯尔公司出版
The idea that food intake is motivated by (or in anticipation of) 'hunger' arising from energy depletion is apparent in both public and scientific discourse on eating behaviour. In contrast, our thesis is that eating is largely unrelated to short-term energy depletion. Energy requirements meal-to-meal are trivial compared with total body energy stores, and energy supply to the body's tissues is maintained if a meal or even several meals are missed. Complex and exquisite metabolic machinery ensures that this happens, but metabolic regulation is only loosely coupled with the control of energy intake. Instead, food intake needs to be controlled because the limited capacity of the gut means that processing a meal presents a significant physiological challenge and potentially hinders other activities. We illustrate the relationship between energy (food) intake and energy expenditure with a simple analogy in which: (1) water in a bathtub represents body energy content, (2) water in a saucepan represents food in the gut, and (3) the bathtub is filled via the saucepan. Furthermore, (4) it takes hours to process and pass the full energy (macronutrient) content of the saucepan to the bathtub, and (5) both the saucepan and bathtub resist filling, representing negative feedbacks on appetite (desire to eat). This model is consistent with the observations that appetite is reduced acutely by energy intake (a meal added to the limited capacity of the saucepan/gut), but not increased by an acute increase in energy expenditure (energy removed from the large store of energy in the bathtub/body). The existence of relatively very weak but chronic negative feedback on appetite proportional to body fatness is supported by observations on the dynamics of energy intake and weight gain in rat dietary obesity. (We use the term 'appetite' here because 'hunger' implies energy depletion.) In our model, appetite is motivated by the accessibility of food and the anticipated and experienced pleasure of eating it The latter, which is similar to food reward, is determined primarily by the state of emptiness of the gut and food liking related to the food's sensory qualities and macronutrient value and the individual's dietary history. Importantly, energy density adds value because energy dense foods are less satiating kJ for kJ and satiation limits further intake. That is, energy dense foods promote energy intake by virtue (1) of being more attractive and (2) having low satiating capacity kJ for kJ, and (1) is partly a consequence of (2). Energy storage is adapted to feast and famine and that includes unevenness over time of the costs of obtaining and ingesting food compared with engaging in other activities. However, in very low-cost food environments with energy dense foods readily available, risk of obesity is high. This risk can be and is mitigated by dietary restraint, which in its simplest form could mean missing the occasional meal. Another strategy we discuss is the energy dilution achieved by replacing some sugar in the diet with low-calorie sweeteners. Perhaps as or more significant, though, is that belief in short-term energy balancing (the energy depletion model) may undermine attempts to eat less. Therefore, correcting narratives of eating to be consistent with biological reality could also assist with weight control. (C) 2016 The Authors. Published by Elsevier Inc.