The people who sit there on Twitter.... who will waste endless hours debating the finer points of their dietary pet peeves who can't do 10 pull-ups is amazing. There should be a rule that says if you can't deadlift twice your body weight and do 15 pull-ups, you shouldn't be allowed to pontificate endlessly on the finer points of nutrition.

The problems that occur in humans, when they are under-muscled are insane ... Our muscles are a sink for glucose. They are the single most important sink we have for glucose. And our ability to tolerate glucose and maintain glucose homeostasis in the presence of larger, more metabolically healthy muscles is the difference between having diabetes and not having diabetes.

I agree that you can just get 80% of [nutrition] right ... The details, the complete optimization, are not worth it, and it's instead better to put that effort into exercise ... If you're going to really go down the rabbit hole and put more of your mental energy, more of your time, and more of your focus into something, you have far more of an ROI on the exercise front than eking out incremental value on the nutrition front.

If you're eating those diets well... you're all shopping on the outer part of the perimeter of the grocery store. It doesn't matter if you're carnivore, vegan, keto, low-carb, paleo, whatever. If you're doing those diets in the way that they were at least thought to exist, you aren't going down any aisles of the grocery store.

I just have a hard time believing that there's going to be an epigenetic signature that I think will be more valuable than some of the most tried-and-true phenotypic tests: V02 max, zone 2 threshold, grip strength, muscle mass, fat-free mass index—all of these sorts of things that are so highly, and I believe causally, linked to longevity.

About 50% of the full benefit of exercise is captured going from nothing to about 15 MET hours per week.

I'm trying to eat a gram of protein per pound of body weight spread out into 4 buckets. There's reasonable evidence to suggest that if you consume too much protein in one sitting, and it's typically more than ~0.25 grams per pound is the general thinking, you're going to end up oxidizing some of that protein.

There are going to be some people who will argue that we have remarkable biomarkers for aging, and then you'll have others—and I'm probably more in this camp—that would argue, actually, we don't really have any good biomarkers for aging.

There is, again, a small number of very vocal and popular people in the field who talk as if changing the epigenome is going to change everything about aging. We have no data to support that.

This idea that reversing the epigenome is reversing aging is at best an exaggeration, at worst an outright lie. I mean, it's just not true.

There was a study that looked at the difference in bone mineral density in people who underwent equal amounts of weight loss—one driven by a caloric restriction strategy, one driven by an exercise-driven strategy. And the exercise-driven weight loss group did not experience a reduction in BMD, but the CR group did.

By necessity, we had to be opportunistic omnivores. To even suggest that our hunter-gatherer forefathers were sitting around pontificating about what they were and we're not going to eat—that's just the dumbest thing I've ever heard.

There are 2 nutritional interventions that relatively consistently give big effects on lifespan: one is caloric restriction, and one is protein restriction.

I think it's really important that we be willing to change our beliefs about nutrition and other aspects of health as more data comes in.

When people talk about epigenetic clocks, what they're specifically talking about are chemical modifications, either to the DNA or to the histones that pack the DNA. And these chemical modifications control gene expression.

Over a very wide evolutionary distance in pretty much every organism where it's ever been studied, you can find evidence the caloric restriction slows aging.

My big concern is that we don't mislead people into thinking that we're close to reversing aging. I think it's a problem from the perspective of the general public; I think it's a problem from the perspective of the scientific communities. Other scientists look at that, and they're like, this is snake oil; this is just not true.

My advice would be: Don't expect major changes in treatments to improve lifespan and healthspan in the next 20 years.

The lifespan benefit from, say, a 30% caloric restriction diet is a combination of when the animals are eating and how much they're eating. Most of the benefit seems to come from the calories.

With rapamycin, the data are pretty clear that you can start rapamycin certainly well into middle age and maybe even at a very old age and get most of the benefits.