Problem being that calories aren't all made the same. Proteins takes more work to release their energy. Roughage like flax seed passes straight through. Even the amount you chew your food can move the needle. So, sure, if you're eating purely junk food like the sibling commenter mentions, you're probably hitting pretty close to the CICO limit. But caloric restriction is really hard to accomplish for some people, myself included, because it's physically painful. And then you look at something like how many miles you need to ride a bike just to match your basal metabolic rate, and people just give up. The CICO mantra is completely unhelpful. It doesn't capture the whole picture, and it sends people on a spiral to failure.