Making Sense of the Different (and Contradictory) Approaches to Life Extension

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by Nils Osmar. Updated August 6, 2023.  Medical Disclaimer

I was born in 1952. That makes me old enough to remember the Cuban missile Crisis, black-and-white television, the “I Love Lucy” TV show, the Kennedy assassination, the early escalation of the war in Vietnam, and an event that occurred during the second decade of my life, the first manned landing on the moon.

I also remember scientists declaring publicly, in radio and television interviews, a few years before the moon landing that it was theoretically impossible, and that human beings could never make the journey there and back alive.

As a little kid, I was interested in the idea of immortality. I liked science fiction, partly because of authors who explored the possibility of societies in which people had done away with, or greatly postponed, the aging process. I read books in which characters lived 500 or 1,000 years, living in idyllic futuristic cities or hollowed-out asteroids traveling between the stars. It sounded nice. Why die, or why die young, if we don’t have to?

I still wouldn’t mind living hundreds of years myself (assuming that I stayed mentally and physically healthy) if advances in medical technology should make it possible. There’s some evidence or at least speculation that this could happen. No one to our knowledge has lived longer than 120 or thereabouts, but as Harvard’s Dr. David Sinclair has said a few times, the first person who will live to be 150 has probably already been born.

How to get there

There are many ideas about what might get us to extreme longevity (or at least keep us alive long enough to take advantage of medical advances that may help us to the next plateau).

Some of the recommendations people run into when they start exploring what might help us reach extreme longevity are conflicting. Some “authorities” recommend eating low protein diets; others, diets low in calories or carbohydrates. Still others recommend optimizing our nutrients and eating a full gram of protein per pound of ideal body weight. A lot of it comes down to which studies you attach the most importance to, what you see as the most likely pathway to life extension, and what approach fits your individual circumstances best.

Disagreement among experts

I was a follower of Dr. David Sinclair’s approach to anti-aging for a couple of years. As I learned more, I’ve come to believe that researchers such Dr. Peter Attia, Dr. Rhonda Patrick, and Dr. Dom D’Agostino, have more practical and useful approaches (at least for me). Sinclair’s ideas are inspiring; I like his confidence that healthy lifespan can be extended; but I’m less sure that his recommendations in terms of how to get there make sense.

One point of agreement…

One thing that almost everyone agrees on is that exercise is essential.

As we age, we lost muscle tone. Doing things like HIIT, Zone 2, aerobics and resistance training would appear to be key to pushing back against sarcopenia. Exercise is often said to be the most powerful anti-aging drug in existence; hundreds of studies back up this way of looking at it.

… and one of disagreement

Most anti-aging “experts” would also agree that it’s good to eat a healthy diet. But when it comes down to specifics, there are many contenders, ranging from vegan to Mediterranean diets to ketogenic and pescatarian, and many others.

They all have advocates claiming that their approach is the best in terms of laying a foundation for healthy longevity. But the truth is that the evidence suggesting that one diet is superior to the others is low quality and often contradictory.

When I post comments about nutrition and longevity, or just write about my own experiences, in online forums, people sometimes ask me – sometimes with a touch of indignation – how I can claim to know more than Dr. Sinclair? Or how I can claim to know more than Dr. Valter Longo (whose recommendations are similar, though not identical to Dr. Sinclair’s)? How can I be so presumptuous as to contradict prominent, highly respected researchers like Sinclair and Longo?

The point is, though, that they often contradict each other. None of the anti-aging or pro-life-extension researchers have identical points of view.

Longo, for example, believes it’s dangerous for people to skip breakfast, and harmful to fast for more than a few hours. He recommends what he calls a “fasting mimicking diet,” but only under medical supervision.

Sinclair not only skips breakfast (and recommends that others do s0), he skips lunch too, eating only one meal a day. (His fasts aren’t water fasts exactly; he snacks on nuts during his “fasting” hours if he feels hungry.) The truth is that no two researchers are in total agreement on the most key and basic questions.

We may have more concrete answers about who’s right (if anyone), and who’s wrong, as more research is conducted. In the meantime, we all have to do our best to make sense of the often conflicting and contradictory data.

What the experts say

  • David A. Sinclair, A.O., Ph.D. is a Professor in the Department of Genetics and co-Director of the Paul F. Glenn Center for Biology of Aging Research at Harvard Medical School.
  • He’s is a big fan of fasting, and believes that daily intermittent fasting promotes longevity. From his POV, e should eat mainly plant-based foods but with a small amount of animal food. He eats one meal a day (fasting till dinner); he has no lunch or breakfast, though he nibbles on nuts during the day if he gets hungry. Sinclair takes, and has spoken highly of, NMN, resveratrol and metformin and a few other compounds. He said recently that the first person who will live to be two hundred years of age has probably already been born.
  • Peter Attia is a Canadian-American physician known for his medical practice that focuses on the science of longevity.
  • He believes that while vegan diets can be made to work with great effort, animal-based diets are better. He believes we need about 1 gram of protein per pound of body weight to maintain muscle as we age. He thinks immortality or even living much past 120 is probably impossible. He takes rapamycin but won’t prescribe it for his patients.
  • He’s stopped taking metformin and views NR, NMN and resveratrol as probably being of little value (though he did recently concede that taking NMN is an effective way of raising NAD+ levels . Attia used to do a three day water fast once a month; now has cut back and believes that doing that much fasting, the frequently, is dangerous and can result in the permanent loss of skeletal muscle.
  • Dr. Dominic D’Agostino is a tenured Associate Professor in the Department of Molecular Pharmacology and Physiology at the University of South Florida Morsani College of Medicine
  • According to D’Agostino, “We should probably all be eating Modified Atkins Diets.” (Modified Atkins is a very high protein/animal food based diet which also includes some low glycemic plants such as salads).
  • In his estimation, we need at least 1 gram of protein per pound of body weight. Ketogenic diets have profound health benefits. People would (in his opinion) probably live much longer if they were on them.
  • Dr. Valter Longo is the Edna M. Jones Professor of Gerontology and Biological Sciences and Director of the Longevity Institute at the University of Southern California –Leonard Davis School of Gerontology, Los Angeles, one of the leading centers for research on aging and age-related disease. 
  • He believes that it’s dangerous to skip breakfast. Believes that high carb, low protein meals will result in maximum longevity. He advocates eating around 45-50 grams of protein a day.
  • He believes that fasting less than 24 hours has little or no benefit and shouldn’t even be called “fasting” — and that even skipping breakfast will shorten people’s lives.
  • He calls his diet a “vegan pescatarian diet”, but some vegans have objected to his using this term because his diet includes fish and cheese. His approach is based loosely on a Mediterranean diet, but actual Mediterranean diets include more cheese, fish, and meat from rabbits and chickens than the diet he recommends.
  • Dr. Rhonda Patrick has a Ph. D. in biomedical science from the University of Tennessee Health Science Center, Memphis TN and St. Jude Children’s Research Hospital, Memphis TN
  • She believes that we should eat the highest nutrient foods available, a balance of animal and plant foods, and not restrict protein.
  • She views both vegan and carnivore diets as possibly being helpful for a short time, but not the best choice long-range. She’s a big fan of fasting. She does not currently take or recommend metformin, NMN, NR. She does take resveratrol.
  • She has noted that we need more protein as we age (and to support muscle synthesis). She has stated that activating mTOR shortly after resistance training is anti-aging. She eats a high-nutrient diet rich in both plant and animal foods, including kale, greens, salads, fish, chicken and eggs. She said that she eats red meat “several times a month”. She recently increased her protein recommendations to about 50% higher than the levels she had previously recommended.
  • James W. Clement is a lawyer and entrepreneur turned research scientist who has devoted the past two decades to understanding the science of life extension. 
  • His POV is that we should alternate between activating mTOR and activating AMPK. (Note: this book was highly recommended by Dr. David Sinclair, in spite of his differences with Sinclair.) It’s dangerous to activate AMPK all of the time.
  • Clement has spoken recently about people whose health took a disastrous turn for the worse when they went vegan in an attempt to activate AMPK full time. He has said that many of them now look much older than their biological age but could reverse that by eating meat and activating mTOR.
  • Dr. Paul Saladino, M.D, is a psychiatrist in Seattle, Washington. He received his medical degree from University of Arizona College of Medicine-Tucson and has been in practice between 6-10 years.
  • After being a strict carnivore for several years, and encouraging others to eat a carnivorous diet, he added fruit back into his diet, and now believes that we should eat an equal amount of meat and fruit, plus honey, but avoid all plants (never eat the plant itself, i.e., the roots or leaves).
  • In his view, plants, which animals have eaten for hundreds of millions of year, are trying to kill animals (not consciously, but through a long evolutionary process in which they developed toxins to kill or sicken the insects and animals – including us – that are eating them. The best longevity diet, from his point of view, is a fruitarian/carnivore diet that’s extremely high in protein and includes no leaves, roots or stalks.
  • Michael Greger, M.D. FACLM, is a physician, author, and internationally recognized speaker on a number of important public health issues.
  • Dr Greger is an advocate of a salt, oil, and sugar free whole food plant based diet. He believes that we can and should get all the nutrition we need from plants.
  • He views animal-based foods as inherently toxic.
  • The best longevity diet (in his opinion) is 100 percent plant-based… no food at all from animal sources (usually referred to as a vegan diet).
  • Dr. Gabrielle Lyon is a physician specializing in the concept of Muscle-Centric Medicine that focuses on the largest organ in the body. skeletal muscle. 
  • Her patients are mainly women in their 80s, many of whom are suffering from sarcopenia and dementia due (she believes) to bad dietary choices made over the years. She maintains that muscle is the organ of longevity. mTOR activation is essential.
  • We all (according to Lyon) need at least one gram of protein per pound of body weight, minimum to avoid Alzheimer’s and other types of dementia. She views animal based foods as nutritionally superior to plant-based foods because of their higher nutrient profile, but has said that a vegan diet can also be made to work with effort.
  • Lyon writes of seeing dozens of her elderly patients succumb to dementia when their protein was low; she was able to turn it around in some patients by getting them to eat animal-based protein, one gram per pound.
  • Dr. Anthony Chaffee, M.D. advocates for a completely animal-based (carnivore) diet.
  • Like Saladino, views all plants as toxic. Unlike Saladino, he also avoids fruit. He believes that meat from ruminant is the natural human diet, and that if people eat it (and nothing else) they’ll be likely to live to around 115 or 120. (He views the carnivore diet as an ideal anti-aging diet.)

As you can see from the short summaries above, the recommendations of today’s anti-aging “experts” are often wildly contradictory, and when they do contradict each other, are all over the map. But even if they agreed, their recommendations wouldn’t necessarily apply to all of us.

My approach

I’ve tried a number of diets over the past few decades. These days my diet is ominvorous, leaning toward animal-based; high in protein; and rich in fats such as avocado oil, fish oil, and other sources of monounsaturated fats and omega 3s. i.e., it’s closer to the diets eaten by Peter Attia, Rhonda Patrick and Dom D’Agostino than those eaten by David Sinclair and Valter Longo

What doesn’t work (for me)

Like everyone, I’ve been figuring out over the years, partly through trial and error, what works for me. This has also given me some data on what doesn’t. To use myself as an example:

  • I grew up eating a standard American diet and was kind of a sickly kid. I was weak, had poor coordination, caught colds and flu bugs, got tonsillitis, was so stuffed up and prone to allergies that I needed nose drops to breathe, felt sad and worried a lot, and had a lot of tooth decay.
  • I moved out on my own when I was 18 and started thinking more carefully about making changes to my diet.
  • I gave up sugar, switched to eating whole grains instead of refined foods, and began eating an all-organic, natural-foods, omnivorous diet.
  • I was doing great actually. But I’d been reading about possible health benefits of veganism and decided to try it for a while
  • So I gave up all animal-based foods, went vegetarian for a few years, then went fully vegan for three years.
  • Doing so initially seemed to give me more energy, but by the third year of following a vegan diet, my health was collapsing. I had lost my libido, and my bones and teeth hurt. I felt angry and anxious and depressed. I had initially lost weight and got rail-thin, then started gaining body fat and become obese.
  • I regained my health and literally all of these symptoms began clearing up when I started eating meat, fish and eggs again.
  • Months later, I tried following a carnivore diet for a few months. (I was mostly-carnivore for two months, then fully carnivore for three). It worked well for the most part, but my eyesight started having problems; it improved when I added foods like wild blueberries back into my diet.
  • A few years later, I went on a ketogenic diet (20 grams of net carbs/day), in part because I needed to lose some excess weight. It worked great for two or three years, but eventually it started feeling too limiting. I was worrying too much about counting carbs, and my sleep started suffering.
  • After that, I went back to eating more traditional omnivorous diet, closer to what someone like Dr. Terry Wahls might recommend (close to what I’d been eating in my twenties.)
  • More recently, I took my diet in a more carnivorous direction, phasing out more foods high in lectins and oxalates. I have no plans though to go strictly carnivore (at the moment). Almost all of the protein in my diet currently comes from animals. Some of the fat comes from olives and avocados. I also eat berries and mushrooms now and then.
  • If I’ve learned anything, it’s that (1) our dietary needs can change over time, and (2) that while it can be interesting to try different diets — in the long run — I don’t “owe” any diet anything.
  • It makes sense (in my opinion) to give a new diet a few weeks or months to see how you feel, and whether your health improves or goes downhill while on it. But after that, if the diet is not working — whether it’s a vegan or carnivore or any other diet — if you find your health getting worse instead of better — or just aren’t feeling good on the diet that you’re eating — it’s not your job to “try to make this diet work.” There are other diets to choose from. Move on.

My current thinking about food is that:

  1. It’s good to eat food from all major food kingdoms) (plant-based, fungus-based and animal-based)
  2. We should aim to eat natural, whole, organically grown foods whenever possible and avoid heavily processed foods.
  3. If we choose to eat meat, the best source (in my opinion) is meat from small family farms where the animals were treated well. Wild fish is better than farmed. There’s some evidence to suggest that our ancestors “became human” and the brain doubled in size during a time when they had access to Omega 3s. So food from the sea is ideal.
  4. It’s good to eat lots of greens, some fruit, some meat, some fish, some dairy (raw is best if a safe/tested source can be found).
  5. Protein (particularly leucine) activates mTOR. So does anything which raises insulin. mTOR activation is not “bad”. Neither is AMPK.
  6. My approach (these days) is to activate AMPK most of the time (primarily with fasting but activate mTOR around 1/4 of the time.


Eating plant-based is one way of activating AMPK (the longevity pathway); another is fasting. I usually fast between dinner and around 1 or 2 pm the following day. I work out in mid-morning, then have a high protein animal-based meal to activate mTOR (the growth pathway, which supports muscle synthesis and immune health).

To me, finding a proper balance between the activation of mTOR and AMPK is what makes the most sense.

I’m also currently…

  • Doing resistance training (I’m currently working my upper body on Mondays, Wednesdays and Fridays, and my core and legs on Tuesdays, Thursdays and Saturdays.) (Sunday is a fasting day, and also my “day of rest”.) I’m on a break from doing HIIT but plan on resuming doing it also soon.
  • Optimizing my sleep (I try to get to bed around 10 pm – good for growth hormone levels, testosterone, and circadian rhythms). I aim to get around 7 or 8 hours of sleep per night.
  • Optimizing my blood sugar (mine tends to run high if I don’t keep an eye on it). (I eat low carb, though not ketogenic, avoid grains, and take benfotiamine and some other supplements to lower blood glucose.)
  • Cleaning senescent cells (aged and decrepit “zombie cells”) out of my body. (I do 3-5 day fasts or fasting mimicking diets several times a year, and also doing a fisetin/quercetin “blast” once a month. Both appear to be effective at removing senescent cells. I’m not worried about having too few senescent cells, because new ones are being created all of the time.)
  • Supporting the growth of new, healthy stem cells. (This occurs naturally7 after a 3-5 day fast or FMD)
  • Taking care of my mitochondria
  • Taking care of my telomeres
  • Dealing with stress effectively
  • Cleaning accumulated debris from my cells with fasting, and from my blood with serrapeptase and other enzymes.
  • Lowering my AGEs (Advanced Glycation End Products) by cooking food over low heat.
  • Balancing mTOR (the growth pathway) and AMPK (the longevity pathway)
  • Protecting my brain health. Preventing Alzheimer’s and other forms of dementia. Exercise and nutrition are key elements of this.
  • Avoiding environmental pollutants, including micro-plastics I use both air filters and water filters in my home.
  • “Living safely.” Buying safe cars. Wearing seat belts. Not driving under dangerous conditions.
  • Restoring some key compounds (including NAD+, glutathione, AKG, nitric oxide, hGH, testosterone, and several others) to youthful level

Me these days

I’m 70 years old at the time that I’m writing this. My health is good. I run a school and teach some classes. My students usually think I’m in my 50s. (We do “guess my age games” in my acting classes in which students anonymously try to guess each others’ ages.) I’m mentally sharp and clear.

I found myself drifting into sarcopenia a couple of years ago but have reversed it and have been gaining, not losing muscle. (See images below) I’m not saying I have the greatest physique in the world, but I’m happy with the progress I’ve been making. The main place where I “look old” is the sag under my neck. I’ve been able to tighten it up a little with exercising but have a ways to go.

I don’t look like an action hero — I’m just a 70 year old guy — but my health is better than it was a few years back, and my sarcopenia has been reversed. I have more energy and mental clarity. My blood sugar is lower, and my cholesterol levels better, than they’ve ever been. My NAD+ levels are those of a man in his 20s. I don’t know how long I’ll live, but neither does anyone else.

Different Strokes for Different Folks

Or course, what’s true for me may not be the case for others. Even if there is an ideal human diet that’s best for everyone, we all have different health issues we’re healing from; Some of us may need more protein (for muscle synthesis) or less food and protein (to promote autophagy and clean the debris out of our cells). Diets can be temporary and can help us (for a while) even if we don’t end up following them forever.

For some folks, going strictly vegan or strictly carnivore for a while might be a good next step. (After that, they can try some other approaches if they want to.) We know ourselves best, and no “authority” can prescribe, sight unseen, for other people.

There’s an old saying which probably applies: “Different strokes for different folks.” Sly and the Family Stone probably said it best:

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Not medical advice

This article is not intended as, and should not be taken as, medical advice. I’m not advising that people eat any particular diet or take any particular supplements, just reporting on what I’m doing. All supplements can have side effects; I would encourage people to research both possible benefits and side effects before starting on any supplementation regimen.  See full Medical Disclaimer

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