Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. In adults, a body mass index (BMI) over 25 is considered overweight, and over 30 is obese.
The food our grandparents ate wasn't any better or worse. But they moved all day. No smart phones or game consoles and for the most part no computers. You can eat all the shit you want on top of a run of the mill diet as long as you work out all day. And probably easily consume 3000 calories without gaining weight (depending on how tall and/or muscular you are).
Who says you have to run that much? I run a little over two miles, once every other day or so, depending on the weather. On non-running days, I use the elliptical. I’m working my way up to 3.1 miles, but no hurry. I currently do much more elliptical than running, which has helped with developing aerobic capacity. No huffing and puffing when running.
https://www.who.int/westernpacific/health-topics/obesity?source=patrick.net
BMI calculator:
https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm?source=patrick.net
https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/english_bmi_calculator/bmi_calculator.html?source=patrick.net