The breakdown of triglycerides into fatty acids for energy involves cleaving them into two-carbon chunks for the Krebs cycle, a process that generates carbon dioxide and requires oxygen.

“So we're going to break that thing down, put it in the blood, move it up, move it into our mitochondria. You can't walk those things across the mitochondria wall. They're too big. So what you have to do is cleave them off into little chunks, and it turns out we break 'em off into two carbon chunks, so we call it beta, as in two, move those into mitochondria. That can go through this little thing called Krebs cycle, or tricyclic acid cycle, and you kick out a bunch of energy out of that. You add two carbons, so as a result of that process, you're going to generate two carbon dioxides. But remember, you can only go through that process if oxygen is available, because you have to be able to place those carbons onto something.”