Oh this is an interesting discussion! *attempts to upvote the picture a few hundred more times* I haven't got much to add, so here, have an anecdote!
Genetics, as pointed out in the disqus comments, makes a huuuuuuuge difference. Case in point, myself vs my husband. Because we spend all of our time within 10 yards of each other, we each eat the same foods in similar amounts (there is some accounting for BMR, after all) and get about the same amount of exercise, but our body types are COMPLETELY different.
I'm a Lalli-type: if I don't have someone actively shoving cheeseburgers in my face several times a day, I start losing weight at alarming rates, especially if I've been exercising. It has to be heavy food too, red meats and dairy and fats--I could never survive on even a semi-vegetarian diet (trust me, my parents tried really hard), and I'll put on pounds from all the sugary soda I drink around the same time the moon falls into the sea. My whole family is made up of short, zippy little hummingbirds like me, though I am the shortest and zippiest of the bunch. Luck of the genetic draw.
On the other hand, my husband is more of a Mikkel-type. He's got 15 inches and almost 200 pounds (40cm, 90kg) on me. His whole family is made up of big barrel-chested slavs whose bodies start efficiently packing away fat stores the moment they get more calories than what's needed just to keep the lights on. They also pack on muscle at the slightest provocation: massive, dense muscle. When I met my husband, his forearms were the size of small dinner plates (and about as soft), and he was known to lift half-ton vehicles off of people in emergencies. He might be able to convince his body to part with some of his fat stores if he's doing consistent heavy exercise AND switches to a mostly-vegetarian diet--but he will be skinny when he's two seconds away from dropping dead of starvation, and no sooner.
Long story short, Mikkel's physique is completely plausible to me. Strictly in terms of BMI he probably would be considered overweight or obese in today's world--but so are a lot of people who don't significantly overeat/underexercise, and are unlikely to have a lot of the health issues associated with obesity. While he clearly isn't underfed, I don't think it's necessary to assume that his weight/build is due to him eating an excessive amount of food either.