18 February 2021
Ask a Longevity doctor is a new show, hosted by me, Chris Curwen, where I discuss all things longevity, health and aging with our friend and colleague Dr. Oliver Zolman.
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In this episode we talk about calorie restriction with optimal nutrition, or CRON. This is a dietary framework based on restricting the number of calories to ~70% of the recommended amount, whilst maintaining levels of essential nutrients. There is strong evidence that it leads to longer healthy lifespan.
Here is what we talked about:
Question 1: There was a couple of experiments carried out in the United States, at the University of Wisconsin and National institute of ageing, looking into calorie restriction in rhesus monkeys? What did these experiments show us about calorie restriction? Why did they conflict?
Oliver: Basically the control groups weren’t properly controlled. So you have to look at the subgroups in each study and compare them. Only male monkeys showed lifespan and healthspan increase, female showed healthspan increase only. It would take half an hour to explain properly, so have a read of my blog post statistical analysis on it if interested.
Question 2: Can we learn something from CRON animals other than the rhesus monkey?
Oliver: Yes, mice that have low IGF-1 and GH still live longer when put on CRON. So its great for finding suggestions of which interventions stack safely and which do not.
Question 3: Are there any examples of individuals who have utilised CRON for an extended period of time?
Oliver: Yes probably over 100, most are members of the CRON society website or Longevity. I have some good slides in my presentation on Michael Rae and Dave who have both been doing it for 30 years.
Question 4: Being constantly conscience of and actively restricting your calorie intake is obviously not the ideal way to live. Are there any ways of artificially inducing calorie restriction, i.e. with drugs, without having to eat less?
Oliver: Basically, no. Rapamycin seems to act through different pathways, as Ames dwarf mice that already have no super low growth hormone, I think, still live a lot longer when on CRON. Eating every other day might do it maybe 20%-50% based on one mouse study, but this seems like a harder thing to do. You could do 10% less calories rather than 20%, thats good. With metformin we don’t really see similar results in biomarkers to CRON, not enough to say its a decent metic, but sure it might be similar a bit in terms of autophagy mRNA levels.
Question 5: I want to know if Huel, or other food replacements, can really replace food. Can you be healthy with no real food but with all the food groups and nutrients that you need?
Oliver: Probably, depending on your biomarker results. Use chronometer to track micronutrient intake. The only issue with Huel really is that some people get fatigue, blood sugar spikes, fat gain or reflux from oats, and theres not really any good RCTs on oats as much as they are lauded. Some kind of vegetable (not grain) that is low FODMAP and similar to oats and palatable would be better.
Question 6: When we as a society look at what we should be or should not be eating the first framework most people probably look at is the national guidelines. But these contain nothing about calorie restriction, which seems to be the healthiest way to live, does this mean they are outdated?
Oliver: Yes, they don’t include CR ! It’s not really useful to say eat 10 fruit and veg a day when half the population will have issues eating them due to FODMAPs, bad cooking technique, causing diabetes or maybe lectins in some people. So it’s not even fit for mass market generic health. At least in Asian populations they stipulate BMI should be 22.5, but in caucasians, 22.5-25 BMI is very rarely associated with healthy biomarker panels like lipids, inflammation, visceral fat etc. Longevity Level 1 diet + CR + FODMAP diet and reflux prevention diet is needed to help population on a whole.
Question 7: What is the role of genetics when it comes to aging and longevity? And how does CRON impact genetics?
Oliver: If we had better genes then we wouldn’t age, so aging is 100% genetic. CRON makes genes less likely to mutate, so reduces cancer and non cancerous mutations, by increasing DNA protection, the same at the epigenetic level.
Question 8: What is the difference between caloric restriction and intermittent fasting?
Oliver: Fasting by definition has nothing to do with calories, just eating window. So you can do IF or CRON or IF + CRON. IF = more than 12 hours fasting generally. So a lot of people do IF without realising it. Most people that do CRON do IF as well.
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