So, I've been a comic book fan for essentially my whole life. Weird powers and old school morality tales blended together in vivid color and delivered at a rapid pace, the medium is really pretty unique. Not to mention how the blending of real science and crazy theories speaks to my inner tech geek. For all that I've always noticed something odd about comic book heroes, their odd relationship with energy. I'm not talking about characters like Iron Man who's arc reactor functions on a form of unobtainium (the exotic element powering his arc reactor, unobtainium for the uninitiated is a plot device in science fiction were writers use a fictional form of matter, energy or what have you to explain a loophole in physics) or even Cyclops who has cellular unobtainium. At least those guys have an excuse. I'm talking about guys like Spiderman and Beast. See, both characters (and a whole host of others) expend a huge amount of energy in terms of intense physical action, physical action that has to be fueled by calories. Most Olympians look like slackers compared to these characters, who regularly make leaps that cover dozens of feet, hurl around amounts of weight that eclipse power lifting records and more.
The problem is where does the energy come from? Well, since these characters are essentially humans with an augmented biology it comes from the food they eat, and while both of the examples are portrayed often enough as having healthy appetites it doesn't scale. Your typical Olympian ingests easilly three or four thousand calories while training and often significantly more than that. You've seen the Olympic Games, oh reader, there tends not to be a lot of spare body tissue (fat) on them. To fuel the significantly higher energy demands of, say, Captain America... well, we're talking tens of thousands of calories. Body builders typically eat several large meals a day (anywhere from five to eight is not unusual, and taken with protein shakes as an add on six thousand calories or more is on the low end of things for a heavyweight body builder) but not Cap. Cap's body and level of exertion in a typical story would usually require several times that effort, he would have literally no time to train due to how much he would need to eat. Even if we say his metabolism is hyper-efficient there are huge demands on his body.
I don't expect this to ever be addressed, and ya, it is a nitpicky issue. Doesn't even stop me from enjoying my favorite titles to tell the truth. It is something that I've noticed for a long time, and no the question is in your head. Enjoy.