These photos bring up an interesting topic. The difference between someone's chronological and biological ages. When asked how old you are, you are likely to answer with the former, the number of years that have passed since you were born.

But if a doctor says you have the physical conditioning of a 50-year-old, they are referring to your biological age. General practitioner, medical researcher, and founder of PrimeHealth Clinical Research, Iris Gorfinkel, M.D., said the difference between the two can vary greatly from person to person.

"It's incredible how what we do determines actually how old we are, "Gorfinkel told Bored Panda. According to her, probably the biggest determinants in our biological age equation are diet and exercise.

"Mediterranean diet has been shown to make people live the longest. Why that is? We don't know exactly. But it has to do with a lot of vegetables, fruits, minimizing the intake of meat, but having some fresh meats, olive oil, nuts, seeds, and grains.

"Exercise holds hands with reducing death from all causes. That's pretty awesome if you think about it. Just a half-hour walk a day can make a big difference. If you do it five days a week, you're pretty much there. Even 20 minutes a day would be enough. The problem is the average North American walks 1.4 miles in a week, it's actually pretty terrible."

Gorfinkel said that we need to push that number up at least a bit. When we exercise, things get better. There's just no way around it. And this brings us to our next topic—sleep. "Exercise improves sleep, which in turn, again, improves our immune function, our memory. Sleep has controls how much we eat and how hungry we are," the doctor said.

All these aspects are connected. Next up, it's important to consider our basic habits, like consuming alcohol and smoking. "The World Health Organization has actually labeled alcohol the number three carcinogen in the world. People do not realize that anywhere it touches is basically associated with potential for cancer." Even colorectal and breast cancer risk goes up with alcohol.

Pretty much the same applies to cigarettes too. "[Smoking is] a big problem to the mouth, tongue, lips, esophagus, and [all the other places it touches]," Gorfinkel said. Some people tend to think that smoking is only bad for their lungs but that is simply not the case. The doctor added she can tell if someone is a smoker or not just by looking at their face!

"The telltale signs of a smoker include hair loss as well as lines around the lips and eyes, and the face, the arm even the breasts can sag in response to smoking."

Not to mention that smoking is associated with increased cardiovascular risk, bone loss and osteoporosis, infertility, low birth weight, and natural pregnancy losses.

Another factor that affects our biological age is stress. And it's a big one. "Stress plays a role in all of these [aspects]. It underlies every single one of them," Gorfinkel said. "When we're stressed, for instance, we're more likely to reach for comfort foods, like ultra-processed foods, which are known to be really bad for us (think high-fructose corn syrups). Those are aging. We want to avoid eating like that.

Stress also underlies our ability to exercise. Gorfinkel explained that if we're really stressed, we're less likely to want to exercise. The motivation goes way down. The concentration to do exercise and just get out the door is just no longer there.

When we talk about the determinants of health, things that control the acceleration of our biological age, we can't help but bring in the social aspects of it as well. "For example, if I'm born to a poor family, if I have a low level of education, if I have a job that I cannot stand and my housing is poor, I am far more likely to live [shorter]," Gorfinkel said.

"If we're to talk about what ages a person, we talk about really a bio-psycho-social model ... Our diet, exercise, sleep, our habits ... Do we have depression, anxiety ... again, you can see the overlap here. The social determinants of health, our occupation, income, education, the housing we have, the neighborhood we live in. All of these things, hold hands, one with the other." The good thing is that a lot on this list is within our control. Gorfinkel thinks that's our goal—to try to identify those things that are truly within our control, and try to control them.

Interestingly, a small clinical study in California has also suggested that it might be possible to reverse the body’s epigenetic clock, which controls a person’s biological age.

For one year, nine healthy volunteers took a cocktail of growth hormone and two diabetes medications and on average decreased their biological age by 2.5, as measured by analyzing marks on their genomes. Furthermore, the participants’ immune systems also showed signs of rejuvenation.

“I'd expected to see slowing down of the clock, but not a reversal,” geneticist Steve Horvath at the University of California, Los Angeles, who conducted the epigenetic analysis, told Nature. "That felt kind of futuristic."

"It may be that there is an effect," cell biologist Wolfgang Wagner at the University of Aachen in Germany added. "But the results are not rock solid because the study is very small and not well controlled."

I guess, if researchers need more volunteers, they can always talk to the parents of old babies.