Aubrey is going grey which would suggest to me if he is practising what he preaches, he's not mastered it yet. Maybe he needs to find out what this cancer drug is doing?
https://www.theguardian.com/science/2017/jul/21/cancer-patie...

He also drinks alcohol, he likes a pint, so perhaps he doesn't know that alcohol dissolves fat soluble vitamins from the liver, which in excess can cause a vitamin A deficiency. What he has is he has done time like a prisoner at these things called university's which generally reward people for academic conformity, having a memory and being able to use logic to argue points when elephants in the room appear. I'm also remind big pharma sponsor uni's in a variety of legal but potentially ethically questionable ways.

Now it should be noted that scientists have known a purified diet shortens life span, so arguably diets which restrict your ability to eat a varied diet, like a shake of sorts, could be doing you more harm, than eating top quality food products and then adding some supplements on top, whilst trying to not over eat.

Anyway read what you like, this is just one of many amino acids and a right mix of opinion which sort of represents life and the medical experts in general.
https://joshmitteldorf.scienceblog.com/2017/02/06/glycine-an...
https://raypeatforum.com/community/threads/aging-in-human-mi...
https://novoslabs.com/novos-anti-aging-longevity-supplement/...
https://pubmed.ncbi.nlm.nih.gov/29136945/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002905/

There is loads to read up on Glycine too numerous to list here, and there are loads of mistakes in scientific studies which if you read enough you can start to spot.

But I will also put this up. https://en.wikipedia.org/wiki/Angus_Barbieri%27s_fast

He had the world record for fasting, there used to be a movement in the 50's in the US called the Hygienists (Herbert Shelton) which was about water only fasting.

Guinness make a good point about unsafe practices, you dont want to deplete your body of some things like Glutathione when fasting, which is something the Hygienists never considered and possibly didnt know back then either.
http://loveandtruth.net/shelton-fasting.html

Other factors with water only fasting and Ketogenic diets is Ketoacidosis, too many ketones and the liver cant handle the increase in acetone, you know nail polish remover! LOL

This probably sums up our medical knowledge best, the graph in the top left of this link.
https://pubmed.ncbi.nlm.nih.gov/?term=glycine&sort=date&ac=y...

An explosion of knowledge where perhaps AI and big data can spot things the existing experts have missed? Like where AI can spot the subconscious bias in judges presiding over parole board requests.

Other points include, what is being taught is not always up to date, who sets the course work and writes the books and some knowledge being practiced is decades out of date and is likely contributing to worse outcomes.

Supermarkets also control the health of the nation because they tell farmers what properties they want in the food they sell, so supermarkets could tell pig farmers, they dont want pigs with a couple of inches of back fat, so the pig farmer goes to the nutritionist, can you reduce back fat, and the nutritionist comes back with a pellet mix which will achieve that objective. Farmer is happy, he is only interested in meeting the supermarkets requirements. He also doesnt know if this pellet mix is affecting the nations health or not.

So this lab grown meat will be interesting, it could end up "meating" the minimum legal standard to be called meat missing amino acids and other chemicals which can be found in the cheapest traditional reared meats, or it could become like a super meat containing everything we need that we can contribute to rude health if supermarkets didnt have profit margins to meat.

Anyway a contentious subject none the less and a very complex one.