These terms may not overlap as much as it seems. A longevity-maximizing action may actually feel like it’s a bad health/fitness state, and vice versa.
A fasting state has a lot of evidence pointing towards increased longevity. Additionally, in various circumstances, a low metabolism state points at increased longevity. Both these cases are not fun to be in as they’re accompanied by fatigue, cold-sensitivity, anxiety, mental slowness or erraticity, and a pale mood. (Though people often detail the positive boosts associated with fasting, those boosts are a relative comparison often stemming from a different set of mechanisms such as reduced inflammation from baseline. It also depends on how long you fast.) How about if one’s skin starts flaking and hair starts shedding more rapidly? As horrifying as it sounds, it actually might depend. In a state of deliberate starvation, this often is a sign of cell turnover to cull the bad/old cells through a trigger of autophagy.
On the other hand, after an intense workout, one feels great and would generally associate that set of actions with better longevity outcomes. Again, the positive boosts are likely offsetting some negative entities/processes, that depending on your own lifestyle, may be present to different degrees. There’s also a debatable potential cost (to longevity in isolation, not necessarily healthspan) to frequent working out as it constantly engages anabolic pathways. Regardless of the opinions on these topics, one should hesitate to just associate “feeling healthy” due to traditional fitness metrics (e.g number of push ups, sit-ups, energy levels, etc) to a contribution to greater longevity. Performance is often orthogonal to longevity.
So what’s a great way to judge one’s longevity potential? This is an open question that many are working on figuring out and I hypothesize about frequently. Traditional metrics have been blood pressure, cholesterol, weight, blood sugar, etc. Some of these metrics still stand strong against new science, but some are coming into question such as cholesterol. Blood sugar and insulin sensitivity are still great metrics as metabolic syndrome is being identified as the root of many more diseases/conditions than previously thought. What’s coming to the forefront are markers of inflammation such as C-reactive proteins, and the newer generation of metrics involving telomere length and DNA methylation (e.g. Horvath’s clock). Definitely google DNA methylation if you haven’t heard about this (hopefully you’ll also become entranced by the spectacular world of epigenetics).
Despite progress in this area, I still struggle to see developments that are directly accessible to me on a frequent basis. If I do a health experiment, I’d like to see how my longevity metrics are impacted. As mentioned above, feeling good or energized is not enough.
Here are my guesses at what might be good signals of longevity that are accessible. They focus on inflammation:
- Body temperature — The outdated view is our internal temperature should be 98.6f. The more updated view is our temperatures vary between 97 and 99 with an average around 97.9f if we had to generalize away all the other factors such as age. Reduced average body temperature is likely a sign of reduced inflammation and that’s actually one of the theories on why the modern average has been dropping since the mid 19th century. When I eat a low inflammation diet for many days, my average body temperature hovers around 97.0f during the daytime.
- Heart rate — Another potential proxy for inflammation and “extra work” that your body has to do.
- Skin & Joints — Inflammation expresses itself through acne, subtle red bumps (like those frequently found on the back of upper arms), skin irritations, joint pain/discomfort. Though inflammation almost affects every part of you, I mention skin and joints specifically since it’s more noticeable for the average person.
- Lower caloric intake with same energy levels — It makes sense to me that if you’re able to function at the same level with fewer calories, your body is processing and using those calories more efficiently. If your body is constantly carrying loads of inflammation, there’s an energy expenditure that goes into the immune system to do that. Also, as non-scientific as this is, it seems to make sense that any chunk of input into your digestive system that’s not converted into energy has a higher prior probability of harming our body than benefiting it. Plus, we can work backwards and also infer that a lower energy capture could signify that food isn’t being digested well — that’s both a sign of poor internal functioning and it leads to further internal disarray as undigested materials flow down the digestive tract and cause all havoc (including, thump thump, you guessed it — inflammation). I wonder if this low intake heuristic could also be applied to electrolytes and vitamins.
Ultimately though, there are a million things we can easily track about our body unintrusively from finger jitters (potentially signaling electrolyte imbalance) to varying temperatures to nerve firings to CO2/VOC/other gases we produce to measurements of stool and urine to density or thickness of our nails. There should be a device that can continuously measure blood pressure. All together, these thousands of data points can be fed into a ml model that gives a holistic overview of how we’re doing on various dimensions.
Also published on my substack.
