To reach any meaningful conclusion or even analyze the issue in a rigorous, scientific manner, one must first define "athleticism" or "fitness" quantitaively. In other words, one must define fitness using a scalar measure (such as BMI, body fat percentage, or some physical performance test such as weight benched or speed in running a fixed distance).
Next, one would need to define what an average chess player is or even what is meant by the term "chess player." For example, if the term "chess player" includes anyone who knows the rules of the game and has played at least one game of chess, I suspect that the average fitness of that group is likely no different than the average fitness of the population at large.
In my view, a serious chess player is someone who devotes significant time to playing chess, studying chess and training in chess. I would define a true chess player as someone who spends at least 10-20 hours per week on chess-related activities. (Notably, under my own definition of a serious chess player, I am not a "chess player.")
Although I do not have any data to support my hypothesis, I would posit that the average "serious" chess player is less fit, on average, than the average person in the population at large (even after taking into consideration that the average person is not particularly fit). My rationale for this is that if someone spends 20 hours of week on chess on top of work, school, life activities, this does not leave a lot of time for exercising or physical activity generally. My only evidence to support my theory is based on anecdotal evidence, i.e., my personal observations of high level (e.g., GMs, FIDE Masters) chess players at USCF tournaments. Even after factoring in age, the tournament chess players (in the Open bracket) seem relatively unfit (at least based on purely visual inspection).
Of course, there may be subpopulations of chess players who are more fit. For example, so-called Super GMs appear to be slightly more fit than the population at large. This could be because their coaches and advisors have stressed physical conditioning as part of their training regimens. This could also be because they can make enough money from playing tournaments and making appearances at events that they do not need a "real" job to support themselves. Or it could simply be that they are financaily successful enough to have a better diet and live a better lifestyle than the average person.
. A rating of 1681 is top 1.9%. If you do not believe these statistics are correct you must take this matter up with the chess.com staff. Making assumptions regarding my sexuality does not compensate for your illiteracy 
I am a head wrestling coach with over 35 years of competing and coaching. I can run a half marathon in 1:54. My body fat % is 11%.