That's a matter of liver health, right? So you could theoretically go higher (by combining antidiabetic drugs with beta-adrenergic agonists, and then sitting in a hospital in a cold water bath hooked up to a liver dialysis machine.)
Not a viable alternative to dieting and exercise, of course, but maybe an alternative to liposuction or gastric-bypass surgery.
I'd suspect the more exercise you do the more that number moves up, you'd be breathing harder. I'd hesitate to try and put a 'hard limit' on anything like this.
A colleague who was into serious mountain climbing said that at 5km it was not enough to eat like 5000 calories per day to maintain weight. He even on purpose gained weight before his trips, and still returned leaner despite eating a lot.
Like the previous commenter mentioned, that's mostly water. I've seen various numbers between 100 and 150 calories burned per mile for runners, which at the high end is just a bit over one pound's worth of calories for a marathon.
I’ve read about people who do things like swim the channel, and bulk up (10’s of lbs) before doing so. Given that they lose this weight in the process, how does that happen?
I think that's mostly independent. A swimmer bulking up for a channel swim is probably putting on a mix of water, fat, and muscle in the slow lead up to the swim (and maybe extra water in the days before) and then losing water during the swim. Here's [0] a discussion of swimmers strategizing about weight gain, and you can see that it's largely about issues like insulation from cold, buoyancy, and strength, and not because they're worried about losing the weight during the swim itself.
"Strong likelihood" only in cases of extreme dehydration. Many wrestlers/ boxers will drop >5 lbs in one day with no longer term impact. The majority of that being water weight they gain right back again.
Well, but you also breath in the O2 first, I think the C just binds to that. C and O weigh similar amounts so it is just 1/3 of the 2 pounds. But you have to count the water loss as well, it is part of fat cells.
How many calories can you max burn per day, around 8000? That would be ~1.1kg of fat loss at 7 kcal per g fat. At a normal day of not eating it is ~300g afaik (2100 kcal at 7kcal/g).
To have such enormous deficit you would have to exercise a lot. And of course you breathe faster during the workout so I think it is entirely possible to breathe out more than 2 pounds of CO2 per day. 2 pounds if probably average for a typical person.
This is noted in the article, in the caption under the second figure.