What if the fountain of youth is just eating less?
Being big and eating a lot is associated with reduced quality of life and reduced lifespan. There are around 1,000 people on earth legitimately 110 years old or older. They all eat once or twice a day, small meals, and tend to be pretty physically capable, healthy, and cognitively sharp.
It doesn't of necessity consequently follow that all people can improve their chances of better and longer life through food restriction. However, as we learn more about the role of fat as an endocrine organ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3648822/), it's becoming increasingly unscientific to think of body fat as merely some sort of inert energy storage mechanism. It plays with various hormonal cascades in a manner which raises risk factors for cancers and all cause mortality.
To boot, it's a very easily confirmed theory (i.e. - just get a glucometer) that frequent eating invokes frequent inflammation. In fact, I think it's a safe bet that all traditional cultures have a season of fasting because they figured out through trial-and-error that it has benefit. Our modern sensibilities are at odds with the idea of doing difficult behaviors; thus, the mere idea of fasting itself can be offensive. But scientific research just continues to confirm that strategic fasting improves all measurable health indices, and may even be able to reverse neurodegenerative diseases (https://www.researchgate.net/publication/44660575_Short-term_fasting_induces_profound_neuronal_autophagy).
We've studied life extension definitively with other creatures, to the point where genetic alterations in worms extended their lives to an equivalent of 500 human years (https://www.medicaldaily.com/life-span-mutant-worms-increased-500-human-years-what-does-mean-aging-therapies-264887). This isn't to say that worms or even other animals make for a good scientific model to reproduce an experiment in humans. Yet, it is really intriguing that, especially in the worm research, the scientists are always targeting insulin and TOR, which BOTH are the very mechanisms we affect when we fast (and exercise).
On the drive into work this morning I heard a piece on NPR about yet another study on longevity and food restriction. This time, the scientists turned their focus acutely toward humans. The study, conducted by Pennington Biomedical Research Center, and published in Cell Metabolism just last month, indicated that calorie restriction does increase ones chances of living longer (http://www.theadvocate.com/baton_rouge/news/business/article_d8b02938-2dd5-11e8-a0f7-fbaa9aada9a1.html). It's not conclusive, since that's just not how scientific inquiry works. But being that it was conducted over a two year period and participant risk markers decreased, its findings are sobering.
The outcome echoes what many other teams have been finding. Just last year, Scientific American showcased a great article on this very subject (https://www.scientificamerican.com/article/the-hunger-gains-extreme-calorie-restriction-diet-shows-anti-aging-results/). In my opinion, the research is a bit of overkill, given that it is just plain evident that abundance can be a problem inherently. It's obvious that modern Western cultural dietary practices are not improving our lives. We are confronted with the stark reality that today, for the first time in about 1,000 years, we are raising a generation of children who on average will not outlive prior generations (http://www.nejm.org/doi/full/10.1056/NEJMsr043743).
Modern life has afforded us many brilliant freedoms and breakthroughs. Still, everything comes at a cost. The human animal was meant for an environment we no longer have. In the same way that we must artificially create activity in our modern sedentary existence, we must artificially create "famine" in our modern overabundant existence. Simply put, for us to live, we may have to starve.