I personally think this is an erroneous view.
Men are obliged to have a lower body fat percentage to look "acceptable". In every fable, tome and story, the perfect male form is powerful, structured, sculpted with a chisel-like detail to his features.
Having experienced both ends of the spectrum, both overweight and fatally underweight, I can state that this is not achievable for some men genetically. I am now nine and a half stones, and have been as low as six and a half stones (through a terrifyingly gripping mental disorder). Though I continuously exercised, I was not able to "sculpt" myself as some men can. This is simply a genetic ideal.
Remember that up until this century the "ideal" frame for a woman was voluptuous, curved and stocky, to indicate they were fertile and energetic. It's only through a very strict mental conditioning nowadays that women seem to believe they should be a size 10; this is literally only 80-90 years old as a tenet and birthed through propaganda and media pressure.
Humans have been in existence for a significant amount of time now, and in all diagrams the males are depicted as incredibly fatless, sculpted muscular statuesque hunters, whilst the women is depicted as an hourglass, beautiful symbol of fertility.
I would say that nowadays, the burden is equal, but not in a good way. Especially not given the circumstances of real life. Men do not have to spear boars any longer; rather their hunter instinct is to shepherd formulae into excel spreadsheets in their office jobs. To expect they'd have a hunter's physique from this level of exertion is pretty much insanity. The only reason a male would appear this way is through the artificial change of his body type (ie, over-exerting at the gym). In the same breath, this notion a woman should be skinny is COMPLETELY counter-productive to who she is as a person, an organism; a WOMAN - the entire point of being a woman is to be an emotional, caring, nurturing individual with the ability to bear another human with all the love and nourishment her body can handle.
I think if we're being traditional - based around human history up until the last century - the man's physique is more difficult to maintain, but only judged by contemporary standards.
But if we're judging solely on what the media SAYS is sexy, then both ideals are pretty much absurd.