Evolutionary considerations on social status, eating behavior, and obesity

Abstract

Lower socioeconomic status (SES) is consistently related to higher obesity risk, especially in women living in developed countries such as the United States and Western Europe. Prevailing theories to describe this relationship have focused primarily on proximate level factors such as the generally poorer food environment (e.g. relative lack of healthy food options and higher concentrations of fast food restaurants) found in lower vs. higher SES neighborhoods and the higher financial costs associated with purchasing healthy, nutrient-dense foods compared to unhealthy, energy-dense foods. These factors are hypothesized to preclude the purchase of these foods by lower SES individuals. Unfortunately, public health interventions aimed at improving the food environment of lower SES communities and to provide financial resources for purchasing healthy foods have had limited success in reducing overall energy intake and body weight. Some evidence suggests these interventions may even exacerbate obesity. More recent hypotheses have shifted the focus to ultimate (or adaptive) factors that view increased energy intake and accrual of body fat among individuals of lower social status as adaptive strategies to protect against potential prolonged food scarcity. The purpose of this review is integrate past research at the proximate and ultimate levels with a consideration of how social status and SES during development (in utero through adolescence) may moderate the relationships between social status, eating behavior, and obesity. Utilizing an evolutionary framework that incorporates life history theory can lead to more integrative and thorough interpretations of past research and allow researchers to better elucidate the complex set of environmental, physiological, psychological, and behavioral factors that influence obesity risk among individuals of lower social status.

Keywords: Eating; Evolution; Life history theory; Obesity; Social status; Socioeconomic status.

Figure 1:

Conceptual model depicting how an evolutionary framework widens then lens for seeing a more complete picture of the factors that influence eating behavior and obesity risk. As depicted in the model, eating behavior and obesity risk are embedded within and influenced by perceived social status and current environmental stability. These perceptions have been shaped and influenced by cues of how harsh and unpredictable energetic resources were in developmental environments (particularly in utero and early childhood). Natural selection has shaped the information that is relevant to communicate about developmental environments (e.g., energetic resource availability/predictability), the cues that communicate them (e.g., through the umbilical cord, breastmilk, and food) and the appropriate behavioral and metabolic ‘strategy’ to adopt given those cues (e.g., in environments where food availability fluctuates, one should eat as much as possible when available, ignore satiety signals, and store fat to compensate for fluctuations) because those strategies predictably led to greater survival and/or reproductive success in such environments over long periods of evolutionary history.