Studies show that calorie restriction and fasting are actually different - during calorie restriction your body reduces energy consumption and metabolism, and while you can lose weight, it's proven hard to stick to and most people put that weight back on.
Fasting OTOH actually increases your metabolic rate [1], stimulates HGH production [4, 5], your brain switches to primarily consuming ketones instead of glucose and your body begins consuming damaged proteins via autophagy. Interestingly enough, studies show weight lost during fasting is better kept off than the equivalent loss with calorie restriction. Your body also resets what it considers 'low' levels of insulin, leptin, etc which can reverse Type II [2, 3]. That can't happen as effectively if you eat.
Yeah I understand that they are different but it's also true that restricting calories overall and losing weight is beneficial no matter what diet you use to do it. So the question is which of the many diets that can do this is the best for your long term health.
The thing is calorie restriction usually leads to full weight re-gain, usually quickly [1, 2], potentially leading to a worse body composition after the diet. The same is not true of fasting [2] - speculatively due to the effect of HGH during fasting which is known to change body composition, reducing fat percentage and increasing lean muscle mass. HGH production is not meaningfully increased by calorie restriction - it's pulsatile and regulated by the presence of any food intake at all almost no matter how small.
Further, there's a string of evidence that alternate day fasting yields substantially improved biomarkers of health (triglycerides, insulin, etc) even if total caloric intake averaged over the two days remains the same (i.e. every second day you eat 2x what you need) and weight does not change.
Weight watchers is an abject failure by their own metrics in a study they published. Their calorie restricted diets are less effective than doing nothing, but being generous, they work for 0.2% of participants who have clearly demonstrated an intent to change their bodies [3]. On the other hand, eat nothing for 36 hours and you're down 1 pound of fat, and it's not likely to come back.
That's what all that talk of yoyo dieting is, and a case can be made that its why the Minnesota Starvation Experiment led to such bad outcomes. They weren't fasting, they were eating a reduced calorie diet - they may have been much better off eating nothing. Contrast that outcome to this, albeit single data point, of a man who ate nothing for 382 days, felt great, wasn't hungry (?!) and lost 275lbs AND kept it all off 5 years later [4].
What I'm getting at here is the science is leaning towards what you're saying not being correct - that how often you eat may be more important than how much, that your body reacts very differently to 6 snacks a day than it does to 1 giant meal every 2 days even if the caloric content is the same. And further that people just aren't built for long-term calorie restriction and to recommend something like that isn't productive.
Your [2] source isn't saying fasting, it's saying quick weight loss. Outside of that one gentlemen who's an outlier in nearly ever aspect you didn't post anything that talked about fasting.
Sorry I was hopping between wifi connections at airports and didn't have the studies I wanted on hand (I don't really keep a stack for any time I want to make a case haha); curious what you make of these papers. In general it's hard to find proper fasting studies on humans due to perception issues though I think that's changing now.
Body composition is better after fasting than caloric restriction even in the event of equal amount of mass re-gain (i.e. regain after CR is fat, after ADF is muscle/lean): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042570/
And here's the mouse study I mentioned (I think I cited rats) showing ADF improves metabolic markers without change in caloric intake, but of course, it's mice, so YMMV: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872764/
In case you hadn't figured it out, I fasted for a while out of personal curiosity and in the spirit of self-experimentation (a few 5-day fasts) and wanted to learn all about what I was getting myself into. Honestly, for the record, it was quite easy; after day 2 I just wasn't hungry anymore. In fact I felt quite energized and focused, which from the studies above, is likely due to increased noradrenaline levels.
Ah sorry I didn't meant to imply otherwise! I wanted to take your point a step further and say that there's something here worth looking more into based on the research I have done over the last few months off and on, that the status quo on eating may be on shakier footing than it seems. It's human nature to assume that something so basic is set in stone, and I like to challenge my own assumptions whenever possible.
Fasting OTOH actually increases your metabolic rate [1], stimulates HGH production [4, 5], your brain switches to primarily consuming ketones instead of glucose and your body begins consuming damaged proteins via autophagy. Interestingly enough, studies show weight lost during fasting is better kept off than the equivalent loss with calorie restriction. Your body also resets what it considers 'low' levels of insulin, leptin, etc which can reverse Type II [2, 3]. That can't happen as effectively if you eat.
[1] https://www.ncbi.nlm.nih.gov/pubmed/10837292
[2] https://www.ncbi.nlm.nih.gov/pubmed/15640462
[3] https://www.ncbi.nlm.nih.gov/pubmed/16051710
[4] https://www.ncbi.nlm.nih.gov/pubmed/1548337
[5] https://www.ncbi.nlm.nih.gov/pubmed/3127426