Two studies by Sell, Lukazsweski, and Townsley (2017) published by the Royal Society examining the preferences of 160 young female raters, found a very strong (r = 0.80) correlation between bodily attractiveness and rated physical strength. Furthermore, they discovered that contrary to popular views about men's bodily attractiveness, there was a linear relationship between perceived strength and bodily attractiveness, i.e the men that were perceived as the strongest were also perceived as the most attractive.

The authors of the study also found that that there was no statistically significant portion of the female sample that had a preference for weaker looking men when evaluating male bodily attractiveness.

In addition, the researchers found that ratings of bodily attractiveness were only weakly to moderately correlated with actual measured strength at r = 0.38 (p < 0.01, when the photos of the subjects were viewed from the front). This suggests that a large part of the contribution of perceived strength to attractiveness is only an 'ornament' (similar to the function of a peacock's tail), and therefore, is not necessarily indicative of actual measured strength. The researchers state that it could also be that some things that contribute to actual measured strength are not viewed as attractive: e.g. excess fat storage.

Quotes:

  • Ratings of strength are a robust and much larger predictor of bodily attractiveness than either height or weight.
  • None of the 160 women in our study who rated attractiveness produced a statistically significant preference for weaker men (all p > 0.05) ... In other words, we could find no evidence that there exists a sizeable population of women who prefer physically weaker men when evaluating male bodies.
  • Height is attractive even independent of making a man look strong. Controlling for how strong a man actually looks, raters still classify taller men as more attractive in two of the three samples.
  • Weight is unattractive after controlling for how strong a man looks...this is consistent with the hypothesis that women's mate choice mechanisms respond to muscle mass positively but large stores of body fat negatively.
  • Height, weight and ratings of strength collectively account for approximately 80% of the variance in male bodily attractiveness.
  • Cues of upper body strength account for most of the variance in men's bodily attractiveness.
  • Contrary to popular theories of men's physical attractiveness, there was no evidence of a nonlinear effect; the strongest men were the most attractive in all samples.

References:

  • Sell A, Lukazweski AW, Townsley M. 2017. Cues of upper body strength account for most of the variance in men's bodily attractiveness. Proceedings of the Royal Society B. 284: 1869. [FullText]