Summary: He's dedicated his life to studying this. A lot of good info. One-star off b/c I think his direction of inquiry is a little disjointed in spots. I think that's the fault of the way research is set up and not the author though. The other star has to do with fact presentation.
I saw Sinclair on a show on Netflix and thought, hey! Let me read this guy's book. He seems to know a lot. And that is true! The writing style of this book is very approachable for a science book.
The early part of the book is about his inspiration. It's a bit irrelevant to the thesis, but it does humanize a topic that may seem inhuman. Not to be petty, but for instance, he says, I am 50, but I feel much younger. Seriously... everyone says that at 50... even at 40 people start to say, I am 40, but I feel 30. plus, I saw you on TV. you look in your late 40s to me and you still age faster than Asian, black, and Mediterranean people do. If going that route, I would have preferred you to simply show the biometrics that shows internal aging. This is pretty popular these days in the field of fitness and used quite a lot to show progress via healthy living, diet, and exercise.
That, however, does not take away from the next chapters that describe clearly the science of aging.
P. 42 gets to the heart of it there is no gene that causes aging. There are only failures in genes that result in the symptoms of aging. This has started to be socialized as a concept, but it's still - at this point in history - new. Even in saying it a lot of people will not appreciate what it means that gene research related to pure identification will not stop people from aging. It is only gene research into function and disfunction causes that will truly help. Because genetic material is so small, this is going to be very tough stuff.
p. 50, He introduces the epigenome. For many, this is new stuff. I wish he would have taken a half a beat more and just displayed what an epigenome is in chemical format vs. DNA and scientifically rather than allegorically it does. I had to look it up and I think, from googling it is a word that describes the changes (not an actual substance) that result in DNA as a result of its use. But how and what the heck that means, I'm remiss, so I spend a lot of this book a bit confused. Hence, menos una estrella!!
That said, this epigenome is the key (hence you can see why it is kinda bad I don't understand it what it is after reading this book.)
p.60, there is a bit more that helps you infer. They talk about this gene called Cas9, the CRISPR gene-editing took in bacteria that cuts DNA at precisely the right places, but again, I can't tell, is that an epigenome, a gene, or something else. Please, Sinclair. You're brilliant. give the little people a diagram with an arrow that says "epigenome here..."
p.96 - This whole calorie restriction thing is as relates to noted improvements to genetic markers is very cool. I also like the example of the guy who's 70, but his heart rate, ldl, and visual acuity were those of a much younger person. I wish he'd just say how much younger, so I don't have to look up the footnote. When I looked it up and read that article, it said his health was similar to a school-age child, with 20/10 vision and BMI in the 20s. It also says that in his 40s his bio age was worse. I think the prob with this author is he's so sensitive to making certain claims that he ought to just go into this whole bio age vs. time age thing and be done with it. Instead, despite good research, it's just ambigious "you don't have to age."
p. 98 - the studies on intermittent fasting and increase lifespan were interesting. specifically, he talks about greater IGF-1 hormone.
pp. 99 - He talks about Ikaria Greece where people live very long lives and do intermittent fasting as a part of their eating style.
p. 107 - Cold exposure is also really good. it creates UCP-2 activation that results from this is correlated with lifespan
So my big thing is that you have this lovely intro where you say, hey.... there is no death marker in the gene, b/c we aren't meant to age or decay. It's all the misfunction that causes it. Then the studies that are presented aren't longitudinal studies that sequentially demonstrate the temporal aspects of this. It's like the wrong research design to prove what you're trying to say. At best, you have this collection of stuff that might be true.
So for example, if it's intermittent fasting, then we see the IGF-1 hormone levels decline over time and have some specific action that happens in the control and with the treated group we see a dip, but then it comes back up or we see no dip over time. Something like that. Instead, we just have tests at a given point of time or at death. Too many variables to really say anything.
Even the way that the bio-age stuff is presented/not presented, we can't really tell because there is no control vs non-control AND, he physically doesn't look younger.
Finally, I really like the tables in the back "The Scale of Things." Very helpful to have various measurements put in the context of things like a grain of sand, a skin cell, etc. I did not know that blood cells were smaller than skin cells. I feel a bit ignorant of biology... in a good way.
In short, this book is great if you're just learning the subject, but it sadly holds back just when it gets interesting. Perhaps that's the audience he's writing for......