I remember reading about a Harvard study that found that those who skipped breakfast every day were more likely to experience a heart attack or die as the result of coronary heart disease.
Honestly, I don’t know if IF is good or bad for you, but what I do know for sure, is that there’s always studies that seems to show both sides of the argument. 
When I want to loose weight I skip dinner, load up for lunch on limitless amounts of salads and vegetables, and for breakfast its brown rice with some walnuts and Japanese natto beans. Depending on the activity level and amounts of calories eaten I get up to 2 pts per week weight loss.
I skip lunch most days of my life. It started when I was studying in college, then working hard to get home in time, and also not feeling sleepy in the afternoon. I still do this in retirement. Just not hungry at lunch and don’t want to feel sleepy. Works for me. Is that considered IF?
And I think therein lies the issue with a lot folks out there, which is consistency.
No… the IF research is showing that mice (who are not humans!) can eat the same number of calories, and if they keep them within certain time windows, they have a different pattern of weight gain (or loss) than those who eat the same calories spread over a longer time. They are studying in humans now – but a lot of the researchers have started doing it themselves.
Kinda tough to study effect of eating patterns in humans… we like to cheat and don’t like to be confined in metabolic cages.
Sometimes they bring people into a facility and keep them there for studies. I think with larger studies they give them an app and have them take photos of food, etc. for tracking these days.
I have a friend who lost nearly 100 lbs, doing IF and he has kept it off for over a year now. He does the 5/2 plan where 2 days per week he eats one mid-afternoon healthy meal of 500-600 calories - and that is it on those 2 days. The other 5 days, he eats 3 meals, reasonably healthy. He also walks 2 miles per day. He is someone who was overweight as a kid and as an adult. Now at 54, first time in his life he is not heavy.
Here, here for @BunsenBurner post about why does breakfast always get the axe and not another meal?! If you eat breakfast, do you really need lunch? Could your IF be between your 7am breakfast and your 7pm dinner?
I have never related the breakfast theory to metabolism (not saying the metabolism idea isn’t true, just saying that I have never worried about that angle). To me, the action I want from breakfast is to provide me with the brain and body energy and fuel my waking time especially during the morning.
I think of food’s benefits to be of what MORE it provides me with - energy, nutrients for health, hydration for skin, etc.
I don’t think of food’s benefits to be of what LESS does it provide me - specifically a number on the scale.
It’s a different way of thinking - what does food ADD to your health. If you do that, you will make better food choices and perhaps mentally have a better outlook on eating.
I want to add - if IF works for you and you are happy, good deal. But also ask yourself if you feel HEALTHY because of IF.
I’ve read a little about IF now and found that I was accidentally doing this as I started exercising this year. After exercise I didn’t feel like eating until at least noon, and that was what I did naturally as a kid growing up (back when I was thin), so I decided to try that for a while. I had been eating breakfast for my metabolism, but all the years I’ve been doing that, I’ve gained and weighed more than the years when I skipped breakfast. Anyway, either the exercise, or the smaller eating window (8 hours), or both, have helped me lose 30 pounds this year, so I’m going to stay doing this for the foreseeable future.
That’s a very calorie restricted diet, so it’s not surprising that a two-pound a week weight loss is the result. But I don’t think most people would stay on a diet like that day after day.
As I’ve posted here before, I lost about 15 pounds on the 5-2 style of intermittent fasting (two days of 500 calories, in my case split between two meals, the rest of the week normal intake). I was able to stay on it because the prospect of being able to eat a non-diet menu the next day made the fast days very tolerable. I’d see some tempting high calorie treat and say to myself, “I’ll have that tomorrow”. So much better than saying “I can’t have that until I reach my goal weight.”’ And by the next day, I had usually forgotten about whatever it was. I also made sure each fast day was fairly heavy on protein and had a variety of textures, and I tried to schedule the fasts for days when I was very busy and had less time to think about food. For me, this approach was so much better than being conscious of the calories (or points, in WW lingo) of every morsel that entered my mouth every day for weeks on end.
But at the end of the day, whatever diet you can stay on is the “right” diet for you, and the success or failure anyone else may experience doesn’t really mean much.
“Why is it always breakfast that gets on the chopping block with these diet gurus?”
One reason is that it’s easiest for people to include hours when they are sleeping and thus for maintaining a “normal” social life breakfast is easiest to skip on fast of at least 14 hours (which I’ve seen as the minimum fast to achieve the results) . If breakfast is not “on the chopping block” you’d have to stop eating by 6 pm to eat at 8 am. I have seen that done but since breakfast is eaten alone a lot more than dinner it’s essier to skip without changing your social life around and thus for many easier to maintain.
If you’re one of those people who wake up ravenous or get a headache if you haven’t eaten by 9 am an IF is going to be harder to sustain and less likely to be successful. If you’re like me and never had any interest in eating til noon, it’s just not a big deal and fits a natural eating pattern much better than a “breakfast is the most important meal scenario” which has been the conventional wisdom for quite some time.
All the people who eat at atypical times: aren’t your mealtimes constrained at all by work or other people’s schedules? I could tolerate a later breakfast, but I have to be at work at 7:30, sometimes earlier. I take lunch when my co-workers take lunch, around 12. I do eat an early dinner, because I have found that I would snack when I get home anyway, so I might as well go ahead and have dinner then, but that is only because recently I have been left to my own devices at that time.
Now I’m interested in trying this or the 5-2 plan. I suppose it couldn’t hurt to try both and see which works better for me.
My ex-H used to eat a snack of fruit at mid morning, then nothing else except dinner. He was (1) quite sanctimonious about it and judgemental of others who ate actual meals besides dinner, and (2) quite grouchy much of the time (I believe the term “hangry” - a combo of hungry and angry - applies). Something to consider and avoid if one goes down an IF path. 
@intparent , that’s good food for thought. I hate being hangry, so it won’t work if that happens. Already it’s been 14 hours since dinner and I’m hungry, but not hangry. But I don’t like being hungry.
I think that IF certainly can include breakfast. Just stop eating earlier in the day. I have a relative who does this. Regular breakfast, bigger lunch. Maybe a light snack at dinnertime (early). He woulldn’t call it IF, but he does follow this to keep from gaining weight.
For myself, breakfast is not a big deal, and I could easily go longer without eating it. I did get suckered in by the “most important meal of the day claptrap” which meant eating when I wasn’t hungry, so I stopped that.
Honestly, my takeaway on nutrition advice that I’ve heard over my lifetime is to not listen to nutrition experts. Although this is coming from someone with a baseline inclination to eat light and healthy, and not born in the US and raised on a typical US diet (defining a typical US diet as heavy on carbs, meat, and fat).
Back in the 70’s it was all, “butter is bad for you eat margarine”, which I totally ignored since margarine tasted terrible and it was cooked up in a lab. Then later, “yeah sorry, butter is actually better for you than margarine after all.” I rarely have butter but when I do it’s high-butterfat European style cultured butter that tastes fantastic so I’m going to enjoy the heck out of it.
Then it was all, “fat is bad for you, drink nonfat milk”. Now it’s all, “Ooops whole milk is actually better for you than nonfat”. I ignored all of that and always had whole milk in my latte.
And who can forget, “switch to diet soda to reduce calories” and now “nvm, artificial sweeteners are not good for you.” I very rarely drink soda but when I do it’s regular.
And throughout the unrelenting drumbeat of “breakfast is the most important meal of the day!”, I would regularly skip breakfast because I’m just not hungry in the morning and actually eating early would make me slightly nauseated. I still watch in amazement over breakfast meetings as my colleagues slam down steak and eggs while I nibble on a 1/4 muffin. Now we hear, “Hey guess what, intermittent fasting is good for you”.
My lifetime rules for eating: Listen to your body. Eat healthy. When you get older spend your calories wisely but eat stuff you enjoy in a way you enjoy. Diets will come and go but lifetime habits last for a lifetime, and the easiest lifetime habits to keep are ones that are in tune with your body and preferences.
^^^ What I would have said, but you said it better
Also a counter argument for ‘it’s accepted and proven science and science is always right’. One only needs to look at the schizophrenic behavior of nutritional science to realize science is always a learning process, and other than established laws of physics, very rarely 100% fixed and correct.