Lack of moving/walking with long periods of sitting, being overweight, no fruits or vegetables and too much highly processed food/junk. It appears to be somewhat self inflicted, but it's hard to live a better life for most as the above is just the norm now.
It’s just about the most fundamental law in the entire universe, in fact.
As someone with Crohn’s disease, I am sensitive to sitting for extended periods and its impact on my internals near my end. I’m sure there is some sort of effect, just curious if there has been any research