> I don't think the existence of elite athletes alters the central point: it is vastly to go into calorific deficit by altering diet than increasing exercise.

You left out the key word in that sentence, which should have appeared after “vastly”. I assume you mean easier, but in fact that’s not true for a lot of people.

> You get to 600+ pounds and you actually need like 20,000 calories just to maintain that weight.

That's wildly inaccurate. It’s more like 5k than 20k. Maintenace calorie requirements are basically linear with weight given similar activity patterns.

Also, most people who need to lose weight haven't already gotten to 600+ lbs.

> You left out the key word in that sentence, which should have appeared after “vastly”. I assume you mean easier, but in fact that’s not true for a lot of people.

Not sure I agree with that. I think it's probably true that adopting even a minimal exercise regimen is easier than adjusting diet, for most people.

But actually turning that new exercise regimen into a calorie deficit is significantly harder. Not only do you have to exercise probably quite a bit per week to get you into a deficit, you have to actively work to not eat more. If you start an exercise regimen, I guarantee you're going to be hungrier, and unless you're very strict with yourself, you can easily eat enough extra to wipe out most or all of the new calorie "savings".