> Furthermore, it's not that simple. Lots of other factors affect metabolism, hunger and energy levels, all of which have huge effect on weight loss\gain.

It is that simple: people simply are looking for an excuses why they aren't willing to do it.

I'm going to again plugin this guy https://hubermanlab.com/how-to-lose-fat-with-science-based-t... because his lectures are amazing and he breaks down the actual scientific consensus on these topics rather well. He is neuroscientist and tenured associate professor in the Department of Neurobiology at the Stanford University School of Medicine who has made contributions to the brain development, brain plasticity, and neural regeneration and repair fields.