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Let’s start with two obvious and interrelated facts that we can all agree upon. The more days that you have been alive, the more likely you are to look older and die. Why? What have you, as well as every other human and non-human animal on this planet, done every day that made you look old and then, ultimately, led to your death?
There’s only one answer: You have been eating and breathing. Eating today gives you the necessary energy and nutrition your body requires in order to live until tomorrow. Thus far, all of what I’ve said is boringly obvious. The most important question is still why? Why does eating make me look older and then kill me?
For the sake of simplicity, let’s not consider what you are eating or whether you are obese. Yes, of course, what you eat does matter and being obese does shorten the lifespan. But what about everyone else who eats a relatively healthy diet, exercises a little (or even a lot) and avoids obesity? Let's also assume that you are living in a cave to avoid the effects of the sun. Well, none of this changes the answer: The longer you are alive, the older you will look, the older you will feel and the sooner you will die. Why?
Eating provides your body and brain with the energy stored within the carbon bonds that are contained within the fats, carbohydrates, and proteins that make up your diet. Breathing brings oxygen to your mitochondria to carry away the carbon debris that forms when these bonds are broken apart. This single critical activity, called oxidative metabolism or respiration, that is absolutely essential for your daily survival, is the most important factor that very slowly, minute-by-minute and day-by-day, ages you until your skin sags, your internal organs weaken and you die. That’s why consuming fewer calories every day is the only effective way to slow the aging process. Eating anti-oxidant rich fruits and vegetables is also helpful. Anti-oxidants in your diet offer some additional protection from the oxygen you are breathing.
Your entire body suffers due to the continued presence of oxygen. [For a colorful presentation of this process and what can be done to reduce its consequences, view my TED talk here.] The brain is exceptionally vulnerable to the consequences of oxygen-induced stress due to its own very high metabolic rate. Obviously, our fast, smart brains came with their own evolutionary price tag. The relationship is linear: The more you eat, the faster your brain ages (along with the rest of your body) and the sooner you die. But why do you look older?
The answer depends upon realizing that the most common tissue in your body is connective tissue. Connective tissue provides support, binds together, and protects tissues and organs of the body. It is found in between tissues everywhere in your body. It literally holds all of your parts together. Due to its abundance and wide distribution throughout the body, it is exposed to the consequences of oxygen-induced stress and toxicity. Therefore, connective tissues are slowly damaged every day and thus parts of your body, such as skin, fat and muscles begin to sag because they are no longer supported against the force of gravity.
Take a look at pictures of yourself when you were younger and you will notice this sagging due to the widespread weakening of connective tissues. The wrinkles in your face show the world that you have lived a lot of days and that each and every one of those days you ate food and breathed. You fed those wrinkles and now you get to look at the fruit of your labors.
© Gary L. Wenk, Ph.D. is the author of Your Brain on Food, (3rd Edition, 2019; Oxford University Press).
