Feeding behavior, obesity, and neuroeconomics

Abstract

For the past 50 years, the most prevalent theoretical models for regulation of food intake have been based in the physiological concept of energy homeostasis. However, several authors have noted that the simplest form of homeostasis, stability, does not accurately reflect the actual state of affairs and most notably the recent upward trend in body mass index observed in the majority of affluent nations. The present review argues that processes of natural selection have more likely made us first and foremost behavioral opportunists that are adapted to uncertain environments, and that physiological homeostasis is subservient to that reality. Examples are presented from a variety of laboratory studies indicating that food intake is a function of the effort and/or time required to procure that food, and that economic decision making is central to understanding how much and when organisms eat. The discipline of behavioral economics has developed concepts that are useful for this enterprise, and some of these are presented. Lastly, we present demonstrations in which genetic or physiologic investigations using environmental complexity will lead to more realistic ideas about how to understand and treat idiopathic human obesity. The fact is that humans are eating more and gaining weight in favorable food environments in exactly the way predicted from some of these models, and this has implications for the appropriate way to treat obesity. KeywordsBehavioral economics; food intake; foraging; closed economy; weight regulation OverviewMost analysts agree that the contemporary increase in body mass index, both at a crosssectional population level and longitudinally within individuals, that is occurring in many parts of the world results from a combination of increased food intake and decreased physical activity [1]. In contrast to this observed increase, theoretical model(s) of control of food intake and body weight emphasize stability. These models are mostly biomedical in nature, meaning that physiological signals in the body and brain are hypothesized to act in a self-regulatory manner to produce an optimal or stable situation for the organism. The foundation of these models is the concept of homeostasis and body weight set point [2,3]. According to such models, if we eat more and gain weight, then several hormonal signals will act in the brain to inhibit further food seeking. Conversely, if we eat too little, the system will increase food seeking and intake, Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. and the net result will be relative stability of body weight across ...

Motivation to obtain a food reward of pregnant ewes in negative energy balance: Behavioural, metabolic and endocrine considerations

“…The feeding motivation methodology, therefore, provides insight into the hunger state of animals. An advantage of using a behavioural demand approach is that it is likely to provide more realistic data on feeding motivation (as opposed to measuring free food intake); food intake is a function of the amount of effort (or time) to procure that food, and economic decision-making is central to understanding how much animals eat (Rowland et al, 2008).…”

“…The feeding motivation methodology, therefore, provides insight into the hunger state of animals. An advantage of using a behavioural demand approach is that it is likely to provide more realistic data on feeding motivation (as opposed to measuring free food intake); food intake is a function of the amount of effort (or time) to procure that food, and economic decision-making is central to understanding how much animals eat (Rowland et al, 2008).Homeostatic mechanisms allow the organism to respond to chronic changes in energy balance and acute changes in food intake. Several physiological signals facilitate the mobilization of energy substrates during Hormones and Behavior 62 (2012) 162-172 ⁎ Corresponding author at: CSIRO, FD McMaster Laboratories, Locked bag 1 Armidale,…”

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“…It is also a widely used protocol for behavioral experiments when a consistent level of motivation is required (see the overview by Rowland et al, 2008), and has been used in numerous studies dealing with food anticipatory activity and brain oscillators entrained by food (for a review, see Silver and Balsam, 2010).…”

Exercising for food: bringing the laboratory closer to nature

“…It is, after all, the choices that animals make that affect their fitness and upon which natural selection acts (Careau and Garland, 2012;Swallow et al, 2009). Other experimental models may approach the decisions that animals deal with in the wild by considering some choices that animals make in order to perform the exercise, such as the relationship between energy expenditure and time spent seeking and obtaining a certain amount of food (Rowland et al, 2008).…”