There is no such thing as a "biological birthday." The term "biological age" refers to how old your cells and tissues are based on physiological evidence, whereas "chronological age" is the number of years you've been alive.
While you celebrate a birthday based on your chronological age, there's no specific date to mark your biological age. You can have a "biological birthday" when your biological age reaches a certain milestone or when you've significantly improved your health and vitality, making you feel younger than your chronological age.
However, it's important to understand that biological age is not a fixed value, and it can fluctuate throughout your life depending on various factors like lifestyle, health, and genetics.
For example, someone who is 40 years old chronologically could have a biological age of 35 if they live a healthy lifestyle and maintain good physical fitness. Conversely, someone who is 30 years old chronologically could have a biological age of 40 if they engage in unhealthy habits like smoking or excessive alcohol consumption.
While there is no specific date to mark your biological age, you can continuously work on improving your health and vitality to reduce your biological age and feel younger.