Do you know to what degree this applies as just a later in rat-life thing? Like... say you have a rat that eats whatever they want whenever they want for their first 2 years. But henceforth are on diets of heavy caloric restriction, or diets with long lengths of time between calorie intake (fasting). Do those rats still seem to reap the lifespan gains? Or do they pretty much have to be on the restrictive diets most of their lives to see any real benefit in terms of life span and/or health in old age?
From what I understand the earlier you start the caloric restriction the better. My thesis project is specifically on long term intermittent fasting started in middle age, so my rats were either free fed until 18 months or until 30 months, and the 30 month ones did worse in every way. But starting it even earlier is associated with better outcomes.
Also this does seem to somewhat carry over to humans, certainly not in all the specific details but as a general rule “be hungry sometimes” is unfortunately good for your health :deeper-sadness:
That's roughly what I assumed. :( Obviously, it would be nice to think that years of very unrestricted calorie intake could be "undone" by adhering to a very strict and severe calorie restricted diet later on, but that goes against intuition, and it looks like the science agrees.
I like to fast sometimes these days (my longest was a 10 day water fast) and genuinely feel like it has significant benefits, but I also realize that as I approach 40, some shit just is as it is and there's no going back and fixing it.
What a fascinating and broadly meaningful project to work on for your thesis! Maybe worth mentioning for the coincidence of it if nothing else: my sister, back in the early 00's did similar studies with rats, ageing, and nutrition for her PhD thesis. I wish I remembered the details better, but it wasn't specifically about caloric restriction. She's a tenured prof at a community college now and writes multimedia textbooks for low-cost or free distribution (because fuck the textbook industry racket). Anyway... massive respect for you delving into the science of this stuff.
Do you know to what degree this applies as just a later in rat-life thing? Like... say you have a rat that eats whatever they want whenever they want for their first 2 years. But henceforth are on diets of heavy caloric restriction, or diets with long lengths of time between calorie intake (fasting). Do those rats still seem to reap the lifespan gains? Or do they pretty much have to be on the restrictive diets most of their lives to see any real benefit in terms of life span and/or health in old age?
Asking for a rat friend of course.
From what I understand the earlier you start the caloric restriction the better. My thesis project is specifically on long term intermittent fasting started in middle age, so my rats were either free fed until 18 months or until 30 months, and the 30 month ones did worse in every way. But starting it even earlier is associated with better outcomes.
Also this does seem to somewhat carry over to humans, certainly not in all the specific details but as a general rule “be hungry sometimes” is unfortunately good for your health :deeper-sadness:
That's roughly what I assumed. :( Obviously, it would be nice to think that years of very unrestricted calorie intake could be "undone" by adhering to a very strict and severe calorie restricted diet later on, but that goes against intuition, and it looks like the science agrees.
I like to fast sometimes these days (my longest was a 10 day water fast) and genuinely feel like it has significant benefits, but I also realize that as I approach 40, some shit just is as it is and there's no going back and fixing it.
What a fascinating and broadly meaningful project to work on for your thesis! Maybe worth mentioning for the coincidence of it if nothing else: my sister, back in the early 00's did similar studies with rats, ageing, and nutrition for her PhD thesis. I wish I remembered the details better, but it wasn't specifically about caloric restriction. She's a tenured prof at a community college now and writes multimedia textbooks for low-cost or free distribution (because fuck the textbook industry racket). Anyway... massive respect for you delving into the science of this stuff.