| Looking Good Naked

Author / Steve (a.k.a. Prof. Booty) Platek

On why men lift weights and desire fitness

Steven M Platek – 18 November 2014

I recently linked an article to the PowerAthleteHQ.com forums on why muscularity (in men) is attractive to the opposite sex. The study, or studies, found a consistent preference among women for guys that had “normal” looking muscularity (Frederick and Haselton 2007). Essentially, what they found was an inverted U-shaped function for muscularity; i.e., men who were extremely low in muscularity (twigs) and men that were extremely high in muscularity (steroid abusing body builder bodytypes) were rated as significantly less attractive on scales that asked 1) is this person attractive and 2) would you have a one night stand with this person.


In this series of blog posts, I’ll call “Looking good naked”, I will discuss the biological and psychological underpinnings to our quest to live on Jacked Street and why looking fit and athletic is attractive, in men and women.

PART 1: What is health?

In the fitness world, we often find ourselves judging people on the basis of their health. “That dude is fat. “He’s jacked!” “She’s carrying a little extra cushioning.” And so forth. It’s completely natural (biologically derived behavior to make visual evaluations of others). This is because we, as primates, have placed a premium on vision during our ancestry (or actually evolution has). Organisms develop/evolve specific sensory adaptations for two reasons: 1) survival and 2) reproduction. In fact, survival is only important insofar as it imparts a reproductive advantage. Take for example your pet canine. His vision is good, but it’s not nearly as advanced as his olfactory processes. As a consequence canids tend to find food, determine dominance, and select mates based on smells. Hominids, while pheromones might be at play (Stern and McClintock 1998) fortunately do not need to use smell for these psychological processes.


Existing data suggest that the traits we (consistently) find attractive are “honest” biological signals to health. This is sometimes referred to as the “good genes” hypothesis. The peacocks tail is an excellent signal: a large healthy and vibrant tail communicates to the peahen that he has a good immune system, that he is able to deal with a pathogen load, and importantly that he is able to bare the burden, or cost, of carrying a large tail (that is very energetically expensive). He’s made it successfully to the mating game – now it’s time to score!

So, while you (probably) don’t ever hit the iron with the thoughts of reproductive success in mind, you’re driven to move and shape yourself in a way that is visually appealing to possible mates. The reason: same as the peacock. You’re nothing but a peacock! Your muscularity signals to women that you are able to do work, to protect and secure resources. Having a fit physique would be indicative of a hunter (from a hunter gatherer tribe) that was successful or capable of procuring resources for hunting efficiency as well as indicate that he is able to bare the burden of carrying musculature on his frame. Testosterone, our holy grail as it turns out, is costly. It actually can have immunosuppressant effects. Therefore, we can conclude that the male who can successfully carry a high testosterone load has a genetic advantage over males who either do not express phenotypic cues of being androgenized or that were unable to bare the costs (e.g., they appear sickly.)

Some people will argue that these data sound like so-called “just so” stories. Stories that are designed to fit the data and support and evolutionary perspective, but take for example the data of (Soler, et al. 2003). They asked a sample of men to provide a semen specimen and took facial photographs of the men. They then asked two separate samples of women to rate the faces on attractiveness. They found that men who had a good sperm index (an indicator of motility, and good sperm morphology) were consistently rated as more attractive and more masculine. Facial attractiveness is tightly linked to androgenization (Penton-Voak and Perrett 2000) and women show variable preferences for cues to masculinity across their menstrual cycle. Repeatedly, science has demonstrated that women prefer more masculinized men during their ovulating, or most fertile portion, of thier monthly cycle.


Training, particularly free weight resistance training that involves varied functional movements performed at high intensity is our best proxy to “work” that could have been done during the Pleistocene. Our Pleistocene ancestors, and modern hunter-gatherers, do not participate in programmed resistance training of the likes of Field Strong. Rather they constantly move, lift, change direction, accelerate, etc. The musculature developed is that of the functional type. This musculature should serve as an honest signal to females that the male is 1) actually doing the work and 2) genetically endowed with the requisite genes capable if developing said musculature. And you might google image search hunter-gatherer men and you will notice that they are not “jacked.” But this brings us full circle to Frederick et al.’s findings. Remember they discovered an inverted U-shaped preference for muscularity. The average young hunter-gatherer male has a physique that resembles a competitive swimmer. But, that’s not to say that more muscle wouldn’t be “sexier”, up to a point. In fact this is precisely what Frederick et al. showed: preference for increased muscularity, up to a point – to a point that they refer to as “normal” or average muscularity, not supra-muscularity.

In Part 2, I will discuss honest biological signals in women’s bodies.

*NOTE: The subtitle of this post is “on why we lift weights…” In biology, why has a very specific meaning: what is the adaptive function of the phenotype. So, while most people report on a ‘why’ those explanations are typically modern based explanations that have an underlying biological/adaptive program. Take for example @john’s response to my forum post. He stated he definitely didn’t start lifting weights to get laid or look good naked. Rather he started lifting weights because his siblings were better than him at sport. Taken from an evolutionary context, this aligns with a biological adaptation. Competition among siblings, including male-male competition for strength and performance is a strategy that is used among many animals to sort out future dominance hierarchies and most interestingly access to mates. The losers are typically expelled from the social unit, left to go fight for access/entrance into another troop. At the end I the day, however, most of this stuff is happening below conscious awareness.


Works Cited

Frederick, David A., and Martie G. Haselton. “Why is muscularity sexy? Tests of the fitness indicator hypothesis.” Personality and Social Psychology Bulletin 33, no. 8 (2007): 1167-1183.

Penton-Voak, I, and D Perrett. “Female preferences for male faces changes cyclically: Further evidence.” Evolution and Human Behavior 21 (2000): 39-48.

Soler, C, et al. “Facial attractiveness in men provides clues to semen quality.” Evolution and Human Behavior 24, no. 3 (2003): 199-207.

Stern, Kathleen, and Marth K McClintock. “Regulation of ovulation by human pheromones.” Nature 393 (1998): 177-179.

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Steve (a.k.a. Prof. Booty) Platek

Steve is a Professor of evolutionary neuroscience, Power Athlete follower since 2011. He co-owns CrossFit Gwinnett in Buford, GA, where he hosts the CrossFIt Football seminar, and he is also a Co-host of Power Athlete Radio Podcast. He's edited three academic volumes and published over 50 peer-reviewed papers on the topic of attractiveness and evolutionary psychology. He is currently acting President of the Applied Evolutionary Psychology Society, an international society for advancing the topic of applied evolutionary science in medicine, psychology, and health and fitness. He founded the academic journal 'Frontiers in Evolutionary Neuroscience'. He played competitive ice hockey growing up and has been a CrossFit coach since 2008.


  1. DavidMck on November 20, 2014 at 6:28 pm

    Loving all the articles. Keep um coming,

  2. Paula on November 22, 2014 at 4:39 am

    I can’t wait for Part 2. . .

  3. Steve (a.k.a. Prof. Booty) Platek on November 22, 2014 at 5:27 am

    @shebeast – the female article needs a little fine-tuning…Hopefully I will have some time over the next few days to sort it out. Thanks for your interest.

  4. Mex on November 22, 2014 at 7:45 am

    Nice work Booty

  5. johnny beers on November 22, 2014 at 12:26 pm

    Interesting stuff

  6. PJ on November 23, 2014 at 2:46 pm

    @luke sorry mate, I can’t login so had nowhere else to put this.

    Since Friday whenever I attempt to login, i just get the message:
    “503: Service Temporarily Unavailable
    Too many IP addresses accessing one secure area!
    Please contact Support if you need assistance. ”

    I’ve tried changing my password, clearing cache/cookies and from multiple devices with no success. Any ideas? Cheers

  7. Steve (a.k.a. Prof. Booty) Platek on November 30, 2014 at 5:18 am

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