The target article provides an evolutionary hypothesis for the relationships between perceived food insecurity and high body weight in humans. However, this hypothesis did not receive strong empirical support. That is, (1) the association between food insecurity and high body weight is restricted to adult women only, and (2) there is no such association in men and in children. Their hypothesis needs some adjustments to accommodate existing empirical evidence. In this commentary, we present a revised version of the insurance hypothesis within an evolutionary life history framework to explain these results.

The life history theory provides a theoretical model for understanding how individuals balance the trade-offs between different strategies associated with individuals’ growth, development, and reproduction at different stages of life (Del Giudice et al. Reference Del Giudice, Gangestad, Kaplan and Buss2015; Kaplan & Gangestad Reference Kaplan, Gangestad and Buss2005). An individual's life history strategy is enacted by the coordinated tuning of multiple physiological and psychological systems, which constantly assess environmental constraints and, accordingly, calculate the energetic allocations (Del Giudice et al. Reference Del Giudice, Gangestad, Kaplan and Buss2015). Individuals’ life history strategies vary based on differences in their early-life environments. That is to say, early-life experiences may calibrate the life history strategies and, hence, may set life history speed. The different life history strategies may adaptively regulate individuals to cope with ecological challenges present in their local environments. Therefore, cues that access to food is uncertain in the early-life stage may influence individuals’ contingent expression of life history strategies, which may subsequently play a role in their approaches to food and dieting in adulthood. We call this the life history model of the insurance hypothesis.

From the life history model of the insurance hypothesis, cues about food insecurity early in life may serve as an assessment indictor to judge the risk of starvation from food shortfall in adulthood. It may be ultimately be indicative of an extreme lack of resources or a hazardous environment where survival is at risk.

For women, these unfavorable cues in early life may promote more immediate reproduction and then induce some behaviors that may promote fat accumulation. This is because female body fat plays a key role in women's fertility regulation – a critical component of life history strategies (Hill et al. Reference Hill, Rodeheffer, DelPriore and Butterfield2013; Hill et al. Reference Hill, Delpriore, Rodeheffer and Butterfield2014). A woman who intends to give birth has to reserve a minimum store of body fat. Therefore, it is predicted that the unfavorable early-life environments with food insecurity may shape a “faster” life history developmental path, which leads to psychological and behavioral changes that promote body fat accumulation. Some experimental evidence, based on the life history model, support this. For example, women who had poorer childhoods responded to harshness cues in their adult environments by showing a greater desire for food and a diminished concern with calorie restriction and weight loss. Conversely, women who had wealthier childhoods responded to such cues by showing a lower desire for food and an elevated concern with calorie restriction and weight loss (Hill et al. Reference Hill, Rodeheffer, DelPriore and Butterfield2013). In addition, a more recent study demonstrated that exposure to current environmental harshness led women from poorer childhoods to idealize a heavier female body size rather than the thin body size typically favored by Western women (Hill et al. Reference Hill, Delpriore, Rodeheffer and Butterfield2014).

But for men, the same early-life cues about food insecurity, which promote more immediate reproduction, may prompt behaviors that promote status enhancement rather than fat accumulation (Archer Reference Archer2009; Del Giudice Reference Del Giudice2009; Wilson & Daly Reference Wilson and Daly1985). This is because the fat accumulation for men may not be advantageous in such unfavorable environments. Conversely, status-relevant enhancement may help them attract more sexual partners and hence access more sexual reproduction opportunities (Betzig Reference Betzig1992; Buss Reference Buss1989; Kruger Reference Kruger2008). This may explain why there is no association between food insecurity and high body weight in men, as shown in the meta-analysis in the target article.

The life history model of the insurance hypothesis elucidates that the resource-relevant environmental factors may have a time effect. For example, father absence early in life shows its effect on women's life history strategy at puberty but not right away (i.e., childhood) (Ellis Reference Ellis2004; Ellis et al. Reference Ellis, Bates, Dodge, Fergusson, Horwood, Pettit and Woodward2003). Body overweight is the same. The life history model of the insurance hypothesis predicts that food insecurity experiences in early life do not influence obesity as children, but subsequently as adults. There is empirical support for this revised model. As found in the meta-analysis in the target article, there is no association between food insecurity and high body weight in children. However, ample studies have provided evidence for the link between unfavorable experiences early in life and body weight in adulthood. For example, growing up in a poor household was associated with increased risk of overweight and obesity in adulthood (Olson et al. Reference Olson, Bove and Miller2007). In addition, a recent meta-analysis indicated that a harsh childhood environment, reflected in childhood maltreatment, was associated with an increased risk of obesity in adulthood (especially for women) but not in childhood and adolescence (Danese & Tan Reference Danese and Tan2014).

In summary, the life history model of the insurance hypothesis would not predict body weight change in children but would predict it in adults, and the effect would be more visible in women. From this revised model, we can develop more specific research questions to test. For example, although growing up in environments with food insecurity may have an effect on increased risk of overweight and obesity in adult women, the effects may exist only in young adult women who are fertile but not in older adult women. For another example, future studies should test whether body weight is influenced by an early-life environment that is restricted only to shortfall in the food supply or one that is generally harsh or unpredictable.