When people will realize that carbs are the only non-essential macronutrient? The sports community (especially bodybuilding) knows that for decades. If an athlete says to me that a thing he does to his body work 95% of the time, I would consider to try it, and already did, some things against over-the-counter conventional medicine like this no-carb diet.
That may have been a bit of a fad though. The single most important rule that I know of is to never mix an animal protein meal and sugar, because that creates triglycerides which harden your blood vessels. This single rule is why fast food is so bad. Cheeseburgers are fine, but add fries and a pop and you just blew it.
As I've gotten older, I've noticed that my need for carbs has diminished greatly. As a teenager, I frequently ate a bag of gummy worms and a 2 liter bottle of pop on weekends. That changed to a case of beer in college. Either of those sound untenable today though.
The single easiest bit of advice I could give someone to lose fat is to stop eating all white fluffies and all sugar. So eat peas, salads etc with each meal instead of corn/bread/potatoes. Then pump iron at least 3 times a week so your body is in a constant rebuilding mode.
You don't really need to watch your fat intake like they recommended 20 years ago either. Always opt for natural fats like avocado, peanut or almond butter and regular butter because you need those to rebuild your connective tissue.
The big secret that nobody ever tells young people is that bodybuilding is all about eating/exercising in ways that elevate your hormones, then strengthening your connective tissue. If you do those things, then muscle and endurance come automatically. If you don't do them, you'll always be emaciated and will eventually get injured.