Hi M! Welcome to the site. I’m neither an expert on keto or rapamycin and autophagy so I’ll just try to provide links to info that I think might help answer the question.
Just to step back for a second - one thing to think about is what are you trying to optimize for? What is the goal? In the past year or so I got much more into keto - partly for the ketosis and autophagy, but also partly for weight loss.
Keto might be good for weight loss, but - what I found that what really helped me for weight loss was the metformin and the canagliflozin. For each of those - in sequence - I quickly and easily lost about 10 to 15lbs during the first month or two of using the medication (the first 3 months for metformin, the first two weeks for canagliflozin). I have tried, with varying levels of effort, to lose 10 or 15 lbs extra I was carrying for the past decade or more… and it never happened. It was really hard and frustrating. But it was really easy (for me at least) with metformin and then canagliflozin. And - its been really easy to keep it off too.
There is research that suggests that rapamycin use can help reset your weight “set point” to the new lower weight so you don’t tend to creep back up to your former weight. That has certainly been the case with me. Previously when I lost weight it always seemed to be hard, and then it also came right back in the months following the loss. With rapamycin and my weight loss this time - there has been no trend like before. The weight stays off, I’m not hungry , and I don’t gain the weight back. Its great.
Here is some of that research, but also anecdotally many people talk about how easy it is to lose weight on rapamycin and keep it off (note, but its not a weight loss drug - with just rapamycin you aren’t likely to lose much weight):
Of course you’ve also probably heard of the amazing success people are having with semaglutide and other GLP-1 drugs. I’ve heard of 20%+ weight loss in the first 6 months… Many people are also speculating that this type of drug would also offer lifespan enhancement for the average person.
My only point here is that if you’re primarily looking at keto for weight loss - there may be easier approaches. And, they can be done in concert with ketosis and rapamycin.
Right now keto is quite popular in the Rapamycin-using community - primarily, I suspect, because two well known rapamycin users (Peter Attia and Mikhail Blagosklonny) are both advocates of rapamycin and the keto diet.
See here Blagosklonny’s current protocol:
Rapamycin and ketosis can, I’ve seen research suggesting, at least partly drive mTOR inhibition and thereby help induce autophagy in the body, which is one way both these techniques are theorized to help improve longevity.
You asked about whether the benefits of keto + rap are cumulative or do they replace one another - and I think the answer is nobody really knows for sure.
There is no way currently in the clinic or in the lab to measure autophagy. How much autophagy, in what cell types, etc. for a given dose of rapamycin, or ketosis (or fasting) really isn’t known from what I could determine. There is a new research that says they have identified a way to measure autophagy - but it hasn’t yet been translated into anything people can access or have used to start establishing benchmarks to answer the type of questions you’re asking - which effectively what is the dose/response relationship between things like rapamycin, keto, fasting, etc - and autophagy.
Here is that recent research on measuring autophagy:
and
Generally - it seems that Attia and Blagosklonny are tending to practice keto all the time, and layering on the rapamycin too.
Here is some of the research on rapamycin and autophagy
With regard to the specifics of MTOR inhibition of keto vs. Rapamycin - I haven’t seen any great discussions or research on this - perhaps others here can add something I have missed.
Some other considerations are what type of Keto are you thinking of doing. I already have high cholesterol - so the traditional keto of eating tons of red meat, bacon, eggs, etc. was not a good option for me. At some point I heard about “Clean Keto” and decided that it was the better option for me - I encourage you to read up on it if you haven’t yet:
Lastly - I think some good resources on keto might be the following:
Anyway - perhaps this is the start of an answer to your question - and hopefully someone with more knowledge than I can jump in with more…