One of the natural causes of obesity is genetic disorder. Some families have entire chains of obese family members spanning across various generations. This is like inheriting obesity for no fault of your own. Sometimes it could also be that a certain unhealthy or non-recommended style of dietary pattern, composition or habit, or outlook towards life and looks, or way of living etc, persists across generations of families or across the entire demography of a geographical location, thereby resulting in several generations of obese descendents. Separating these factors as genetic or attitudinal or demographic or geographic etc. is not only cumbersome but also expensive as well as time and energy consuming.

Modern obesity is also a byproduct of environmental factors such as sedentary life, in terms of more and more desk-based office jobs, that have taken over manual and labor jobs, with most manual or labor jobs getting automated with computerized, mechanized, gigantic, and robotic machines etc. Another major environmental contributor is the commercialization and popularity of unhealthy foods such as junk foods, alcohols, sodas, sweets, sweet drinks, tinned, canned and processed foods, ready-to-eat and ready-to-heat meals etc., which are rich in dead food, zero nutrients, fats, trans fats, saturated fats, cholesterol, preservatives, germicides etc., which contaminate and debilitate the human body with widespread morbid obesity across a sedentary generation.

Excessive work, projects, deadlines, tough competition etc., force people to stick it out to their desks late into the night, and compete and perform, in spite of starting work early in the morning. This upsets their work-life balance, thereby leaving them with very little time and energy to work out and maintain a healthy, trim and slim body. Long hours at work promote musculoskeletal and respiratory disorders, which in turn promotes resting at one place, which in turn feeds obesity. It's like modern man getting trapped in his self-created cob-webs of work and development. People have stopped working to live and have begun living to work, which leads to a path called "nowhere". They have forgotten that health is wealth and that working out is a must, even if it's just half an hour a day, and only 3 days a week.

Temptation and status-quo could be other reasons for obesity. This temptation could be towards the various junk food items, as promoted in adverts. Or it could be due to the need to maintain status-quo through a laid back, lackadaisical and lethargic outlook towards life, whereby one tends to not move from his/ her place, because everyone else is sedentary, so the "why-even-try-something-different-from-others" attitude. 

The causes as illustrated above are some of the major reasons for modern-age obesity, and we as a society, and as the enlightened human race and civilization, need to take a more pro-active approach towards our own health and towards eradicating the evil of obesity.