[jeremy151]

The complication is that long term weight loss is functionally a behavioral challenge, and getting human beings to make long term behavioral change is not easy. Sure, maintain calorie balance or deficit and you'll be fine, but it's exceedingly rare that someone will track calories for their entire life. So we're left with either retraining their ability to intuit what they should be eating on a daily basis, and/or eating the types of foods that tend to make this job easier. That's where you start to end up with all the varied advice—it's an attempt to overcome behavior. If everyone had a perfect willpower, obesity would be an easy solve.