Frequent consumption of fast foods (≥2 times/week) was only weakly associated with increased odds of being obese; some evidence suggests healthy food interventions may even exacerbate obesity

Evolutionary considerations on social status, eating behavior, and obesity. Ann E.Caldwell, R. DrewSayer. Appetite, https://doi.org/10.1016/j.appet.2018.07.028

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.

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Regardless of SES, frequent consumption of fast foods (≥2 times/week) was only weakly associated with increased odds of being obese (OR=1.35, p=0.06), and the relationship between neighborhood access to fast food and its consumption was weak and only borderline-significant. Another observational study of over 8000 participants found that higher net wealth (total assets minus total debt) was associated with slightly less overall fast food consumption, but that higher income (rather than “wealth”) was associated with a greater number of fast food meals in the past 7 days (Zagorsky & Smith, 2017). However, the authors noted that the associations were weak and unlikely to have a large public health impact. As an example, a $1 million increase in net wealth was associated with consuming only 0.7 less fast food meals per week.