Updated: Jun 24
The medical information has been extracted from a summarisation of the podcast between David A. Sinclair and Shane Parrish as a part of The Knowledge Project Podcast.
When we talk about ageing or life-extension, the first question that is posed is—Why is biological ageing a problem? Isn't it natural for us to age and die over time?
David A. Sinclair however points out that the very fact that we dont consider ageing as a problem is a real problem. He notes that it's possible to live another 100 years while remaining physically and mentally fit.
If there was a special Olympics for centenarians (100+ year olds), would we be able to participate in that?
What really happens to our body as we age?
According to the Information Theory of Ageing, through ageing, cells lose information making them degrade over time and the diseases kill us. To shed some light on what's going on, Sinclair gives this analogy of a DVD player. As you play the DVDs, they tend to get scratched over time and gradually lose information.
Ageing is like scratching, with DNA base pairs tending to comprise of broken chromosomes.
If we could figure out a way to polish the scratches and play sweet music again, can't we do the same with reversing ageing?
Here are some concrete steps taken from the podcast excerpts on how we could live a life of longevity—
Reduce the meals
We've been told over and over again that breakfast is the most important meal of the day. It's not true. We don't have to eat three/four meals a day.
Sinclair suggests to reduce the time interval between our meals. Instead of separating three meals in regular intervals, we could take in the same calories over a much shorter time interval. Body being the best when it's not hungry is a myth.
The hormones which kick in to make you feel hungry is a short-term consequence. In 3 weeks, this artificial hunger also goes away if we're consistent.
The most common version of this method is called as the 16:8 fast, where you eat as much as you can within the 8 hours, and leave out the rest 16 hours in a day for fasting. Sinclair practises a more extreme version of this (OMAD) - One Meal A Day which has proven longevity benefits as it kicks in the process of autophagy.
Drink lots and lots of water and hot tea to suppress our hunger while getting used to this diet.
Always have carbohydrates after you have protein. Doing it the other way round spikes your glycemic index.
Prefer plant based diet over a meat based diet due to the lower ratio of amino acids. 
Avoid gluten, sugar, meat as much as possible
What doesn't kill you makes you stronger
Friedrich Wilhelm Nietzsche's quote —'What doesn't kill you makes you stronger' has a lot of potent biological implications. In our human body, this antifragility observed is nothing but autophagy — a conserved degradation of our cells to remove the unnecessary and dysfunctional components over time.
Not just us, but even plants undergo such stress while being exposed to extremes of temperature variation, water or nutrient availability. Environmentally stressed plants have been proven to produce therapeutic bioactive compounds with proven health benefits, also called as xeno hormesis.
For example, the light stress on a cucumber is found to be helpful in treating arthritis and cardiovascular diseases. Mustard when exposed to mild bacterial or fungal infection has been proven to fight cancer.  And some of them have been shown to have benefits when it comes to longevity.
Matcha tea which is grown in shaded conditions produce xeno hormetic molecules which boost their body's defences.
Eating bright fruits is always a good idea owing to the induced process of xeno hormesis which creates such vivid colors.
While picking an ideal diet, we can take these factors into consideration. 
Sleep, Exercise and Wellness
The exercises can be primarily divided into three major categories to check on our lung health, heart health as well as our muscle health.
Yoga and Pilates for flexibility
Weightlifting for maintaining our muscle (we tend to loose upto 1% muscle every year)
Aerobic exercises for our lung capacity— every week, we could lose our breath alteast 3 times a week for 10 minutes to maintain this capacity.
To sleep atleast 7 hours a night 
Meditation as a part of our pre-bed routine
Regular saunas could induce thermal shock proteins within our body
Our regular diet does not entirely provide the exact requirements for a longevity based diet. The following is not medical advice. These are just some of the supplements endorsed by David A. Sinclair to live longer. He suggests the following—
1g per day, in the morning can boost the production of NAD. As we get older, we tend to loose the production of the chemicals. 
Resperitol is produced in grapes every morning.
1g per day, in the morning. As it's insoluble in water, it's advisable to mix 2 tbsp of yoghurt with 1 gm of resperitol so it gets absorbed.
For those primarily on a vegetarian diet, athletic greens provides the dosage of multivitamins, minerals and probiotics.
Vitamin D deficiency in humans has been associated with an increased risk of heart disease, type 2 diabetes, autoimmune diseases and Alzheimer’s disease. Vitamin D can reduce the risk of various aging-related diseases.
Plants make molecules that are very healthy for us. In addition to anti-oxidants, they activate sertuin genes which have been proven to expand our longevity.↩︎
Hooper, P. L., Hooper, P. L., Tytell, M., & Vígh, L. (2010). Xenohormesis: health benefits from an eon of plant stress response evolution. Cell Stress and Chaperones, 15(6), 761–770. https://doi.org/10.1007/s12192-010-0206-x↩︎
The Okinawa diet of Japan is believed to have contributed to the exceptional longevity of the people there. Even Mediterranean diet has been shown to reduce ageing owing to their excessive consumption of fruits, vegetables and olive oil. ↩︎
This is an important factor as our sertuin genes might get disrupted owing to lack of sleep↩︎
NMN has been shown to slow down many aspects of aging in animal studies (1,2,3,4).↩︎