Earlier quoted context omitted.
> This approach is generally referred to the calorie-in/calorie-out (CICO) model. While true to an extent, this perspective is too simplistic, given one key fact: leptin is primarily produced in adipose tissue [1]. This fact means body fat is actually an endocrine system organ. This part I think needs more explanation. The reason calories-in/calories-out model is too simplistic (I would call it almost useless if not…
CICO doesn’t work across individuals for reason you outline (just because I lose weight with a certain level of calories, doesn’t mean you will, etc.) But for a single individual, working to establish your base metabolic rate by counting every calorie and weighing yourself regularly, you can always find a way to be successful with the CICO model. If you establish a baseline that your metabolic rate is (say) 2000 calo…
> If you establish a baseline that your metabolic rate is (say) 2000 calories a day, then eating 1600 calories a day will cause you to lose roughly a half-pound to a pound per week.
At this point it's pretty safe to say that's likely untrue at the population level. This is a cutting edge area of research but the UCP1 adaptations seems to happen really fast, for some people on the order of weeks. On the order of months for the vast majority of the population. It doesn't take long for the basal rate to fall to whatever your intake is because the system evolved to naturally have a lot of room to spare. The human body always adapts and if I were a gambling man, I'd say this is largely why most people fail at dieting: after a month or two the results stop and they have to further decrease their intake which interferes with other pathways and tanks motivation.
If it works for you, that's great! You're one of the lucky ones, maybe because you've hit your floor for uncoupling proteins. But given just how hard dieting is for most people and how bad the obesity epidemic has gotten, it's probably not useful for the majority of people. A far more holistic approach that tackles macro- and micronutrient deficiency, motivation, lifestyle, and not just net calories is required.