As an example eating a whole cake is generally considered unhealthy and a bad kind of stress for the body do to excessive calories and the glicemic level increase. Same thing when it comes to not sleeping enough.
Exercising and other activities on the other side are seen as fundamental to live a healthy life.
What exactly determines the difference? Is it just a matter of whether or not our body can “improve” following the stimuli? And why does our reactions varies so broadly?
In: 1
Our bodies have spent thousands of years evolving to live like most animals do, on a survival basis, and that tends to be what determines whether something is “positive” in this sense. It’s less about individual stressors and more about the overall machine working as intended.
We all need to eat, of course, but as of only the last century (a tiny amount of time in the scale of things), most of us in the west are eating more than all we need every day. Early humans would have gone for days without a large meal, and would have very limited natural sources of sugar. So our system still tells us to crave those things, but it hasn’t evolved to be able to handle an entire calorie-rich cake. That flood of excess sugar and fat is not something the human body is used to metabolising, and that can lead to a buildup of problems. (No judgment or shaming in this comment intended for anyone who struggles with eating – cake is great and I love it.)
On the other hand, intense exercise IS something we’ve evolved to do an awful lot of, and even though it might feel stressful in the moment, our system is meant for that level of movement and suffers from a lack of it. And as you say, it improves the body, stretches and strengthens muscles.
Of course it’s not always cut and dry – for example, if you haven’t eaten, blood sugar is low, and you feel miserable, a slice of cake will have a positive effect. And people who overexercise end up with long-term health problems, or a mental addiction, and that is a bad level of stress.
Latest Answers