It's a fairly strong statement that despite a lot of studying, no evidence of any meaningful benefit for weight loss, and no benefit at all for CVD is found.
There could be other benefits, of course.
In fact, personally, I tried IF and what I found to be the greatest benefit was sleeping better. All I really have to do to maintain that same benefit is stop eating a couple hours earlier than I did before IF, and that's ... if we're being honest here ... that's long and well known good advice: don't eat near bedtime. For me it just didn't click that it meant don't eat several hours before bedtime as opposed to say, 30-40 minutes before bedtime.
Anyway, it's not surprising to me that little benefit is discovered so far from IF. It is an interesting idea, but, not much of a mechanic associated with it to explain any benefits. Most aspects of our metabolic processes do not work timeframes below a few days.
Actually, the parts that DO work on short time frames related most strongly to the health outcomes they stated could not be judged by the studies, including glucose impact. So I guess cross your fingers that in the future it can be shown that IF helps glucose management and reduces diabetes risk/impact.
There is no evidence from this trial to refute the null hypothesis, which is to say there is no evidence from this trial that IF provides any protection from CVD.
I encourage you to try IF for a longer period. A week or two. There’s an adjustment period after which it becomes easier and then becomes the norm.
Also I find low carb, but not necessarily keto works better with IF. Essentially the goal is not to spike insulin too often.
The reason IF works for me is that I know I can eat pretty much what I want so long as it's reasonably healthy (lots of veg, fruit) and I only do that once a day.
A traditional calorie controlled diet works also in the short term but it's miserable and, eventually, I break just as, anecedotally, most other people do too
The body is a complex system, and different people's bodies work differently. Really, what I want to know from a diet study is were their negative effects, and did it work for a significant amount of the people. Ideally, for those who it seems to work, do a longer term study to look for negative effects and long term results for people who stick to to it. If you get enough of these studies, and I'd like to change my diet to control my weight, I can try things until I find one that seems to work for me, and have some confidence that it works long term for people who it works for.
One diet to rule them all is the same thing as everyone should run the same HTTP server. I love apache, but different systems work better with different servers.
What I am trying to say is, you are totally right here. I suffer from IBS, and if I just try IF for one day my entire guts go really nuts (I have mixed type of IBS).
The correct thing is to do the exploratory study, notice that some group seem to respond well, then run a new study “IF for the prevention of CVD in <specific subgroup>”. That’s a lot to ask, of course.
Edit: Removed own interpretation to let the authors speak for themselves
Personally I just say “I don’t eat breakfast.”
Most people define IF as eating within a 12 to 6 hour period each day. For most people this is literally just skipping breakfast and eating lunch & dinner.
That said, not everyone agrees on the method. Some will skip entire days intermittently, so, this whole discussion is shaky overall, but, definitely agree that "skipping breakfast" is not IF.
For me personally, „skipping breakfast“ comes close enough as an oversimplification in practice.
Most people will also never be on board when one touts it as "skipping breakfast", as for them that's a negative experience. For me, never eating breakfast is ok, as my body is used to it. But for those used to eating it, the days they don't get their breakfast equals a bad morning. Either because of the circumstances leading to them not getting to eat (overslept, stressful morning), or in combination with an unusual feeling of hungriness and tiredness.