Aging means a progressive deterioration in physiological function and increasing susceptibility to disease and injury. In a nutshell, age means that the body weakens. Therefore, to deter aging, you have to be strong and remain that way.
The most obvious way to stay strong involves exercise, and especially the form of exercise we like to follow here on this blog, weightlifting. Lifting weights causes the body to adapt to the stress of being forced to lift weights, all the more so when done to failure.
The body possesses plasticity, that is, body tissues and organs can change their size and structure according to the environmental pressures placed on them. In endurance athletes, the heart gets bigger in order to pump more blood and allow the athlete to perform at a high level for a long time. Capillaries grow to bring that blood into the tissues where oxygen is needed. For weightlifters, muscles and even bone grow bigger and stronger – even tennis players develop heavier bones in their dominant playing arm. In people who have lost one of their kidneys, the other kidney becomes larger to take on the task of shedding waste products.
Exercise like this exerts stress, which is a response of the body to any demand for change, in the words of the psychologist Hans Selye. Hit a tennis ball hard enough and long enough, and sufficient stress has been placed on the bones of the arm to cause a response: they grow larger and stronger.
We can use the concept of exercise as stress as to look a the effect of other health-promoting processes on the body, for the fact is that many things that promote health do so by increasing stress. Hormesis, for example, just is, that is nothing but, the placing of a stress on cellular or organ systems. Calorie restriction and intermittent fasting, for instance, are stresses placed on the body, and the body up-regulates stress defense mechanisms. When CR or IF are practiced, there is an increase in free radicals (reactive oxygen species, ROS), and these act as signals for the cell to increase its defenses.
…several longevity-promoting interventions may converge by causing an activation of mitochondrial oxygen consumption to promote increased formation of reactive oxygen species (ROS). These serve as molecular signals to exert downstream effects to ultimately induce endogenous defense mechanisms culminating in increased stress resistance and longevity, an adaptive response more specifically named mitochondrial hormesis or mitohormesis.
The older free radical theory of aging posited that ROS caused aging by causing damage. A newer way of looking at it is that damage is necessary, causing increased adaptation to stress, and thus promoting health and longevity. More mitochondria are produced, and levels of the antioxidant enzymes superoxide dismutase and catalase are increased, as well as enzymes that produce the endogenous antioxidant glutathione.
Other longevity-enhancing agents work much the same way. The phytochemicals in fruits and vegetables, and in substances like resveratrol and curcumin, are perceived by the body as toxins, i.e. they place a stress from which the body acts to defend itself. This is even the case with frankly poisonous substances, like arsenite. In effect, what doesn’t kill the body makes it stronger. As Nietzsche called this aphorism, it’s the military school of life.
Antioxidants can abolish the health-promoting effects of exercise. The reason that they do this – or possibly could do this, research is ongoing – is because they abolish the cellular signals, ROS, that indicate that a stress is being placed on the body. No stress, no adaptation.
Radiation can also promote health in the same way, by placing stresses on cells, which then essentially fight back.
Psychological stresses can be healthy as well, such as missing half a night’s sleep. And for the brain, all of stresses mentioned above work on it also, increasing levels of brain-derived neurotrophic factor, and causing the growth of new neurons.
What happens when not enough stress is placed on the body? Diabetes, for one. Or by constantly feeding your body everything it wants, and never depriving it, obesity. It’s the couch-potato lifestyle, the body always in a non-stressed mode. Plenty of health-promoting agents are non-stressful, like food, sleep, and sex, for instance. (Maybe there’s something to the denial of sex in asceticism that really does promote health. The use of pornography definitely does not.)
But, if you deprive yourself of stresses like those discussed above, you will not be healthy, nor are you likely to live long. Hardening and denying yourself, not always giving in to the demands of your psyche for comfort, a certain degree of asceticism, are essential.