Not sure what the significance of this study is, but it's interesting. If I had to make an evolutionary guess, I'd wager that slightly larger women signify health and resilience while skinny, model types seem rather frail and not adaptable to stress.
You can read the whole paper at the link below - it's from the open source PLOS ONE.
Viren Swami, Martin J. Tovée
BackgroundPrevious work has suggested that the experience of psychological stress may influence physical attractiveness ideals, but most evidence in favour of this hypothesis remains archival. The objective of this study was to experimentally investigate the impact of stress on men's judgements of female body size.
MethodsMen were randomly assigned to either an experimental group, in which they took part in a task that heightened stress (experimental group, n = 41) or in which they did not take part in such a task (control group, n = 40). Both groups rated the attractiveness of female bodies varying in size from emaciated to obese, completed a measure of appetite sensation, and had their body mass indices (BMIs) measured.
ResultsBetween-groups analyses showed that the experimental group was matched with the control group in terms of mean age, BMI, and appetite sensation. Further analyses showed that men in the experimental group rated a significantly heavier female body size as maximally attractive than the control group. Men in the experimental group also rated heavier female bodies as more attractive and idealised a wider range of female figures than did the control group.
ConclusionThis study found that the experience of stress was associated with a preference among men for heavier female body sizes. These results indicate that human attractiveness judgements are sensitive to variations in local ecologies and reflect adaptive strategies for dealing with changing environmental conditions.
Citation: Swami V, Tovée MJ. (2012). The Impact of Psychological Stress on Men's Judgements of Female Body Size. PLoS ONE 7(8): e42593. doi:10.1371/journal.pone.0042593