> the kind of exercise regime that allows eating loads of food is generally only accessible to people who are already extremely fit.
Of course. And I'm not suggesting that people ignore or go crazy with their diet. I'm personally very strict with mine, though I'm not counting calories at all but rather trying to mimimize salt, saturated fat, and added sugar (which perhaps naturally restricts calories somewhat, since the highest calorie foods also tend to have high salt, saturated fat, and added sugar).
> But if my 240 lbs buddy wants to lose weight? Dude would be doing well to jog 5km. He's not going to be running any marathons.
Of course. What I would say is that in fact it's a (metaphorical) marathon, not a sprint. The goal, I think, should be health, not simply weight loss, which is only one aspect of health. You shouldn't be afraid to exercise strenuously just because it might make you a little hungrier. In the long run, you want to control your diet and also get your body into shape, which requires investment in exercise.
My dispute is with the idea that "we burn calories within a very narrow range: nearly 3,000 calories per day, no matter our activity level." That's simpy not true in general. It may be true for a relatively sedentary activity level, but it's not true for people who are at higher levels of vigorous activity, and I don't mean just elite athletes. A normal person can build up to becoming quite physically active if they commit to it long term. Of course nobody can just run a marathon right away, but almost anybody could run a marathon eventually. The author was examining people who walk all day, but I don't think that's a good baseline for measurement of "maximum" physical activity, because walking is generally not very strenous.