Am I misunderstanding something or is that article saying “it’s not CI/CO, it’s actually CI/CO”? The incorrect assumption people make is that somehow the only change to energy intake and expenditure is food and exercise (which we have known for very long to not be the case and it’s insane to me that people believe that), not that the law of conservation of energy somehow doesn’t apply. If you expend more energy than you take in, you will lose weight. But measuring either of these things properly is close to impossible and certainly not as simple as “put your height and weight and what you eat and how much you exercise into a calculator”.