Why are most people are fat nowadays?

Unhealthy foods are frequently the cheapest, and we don't have time/energy to cook properly for ourselves or exercise. Everyone just works all the time. And you don't necessarily get much physical activity in at any given job.

I don't think it is fair to say that everyone who is overweight is simply lazy and uncaring about their health. It's complicated.

Bigger portion sizes being served, fast food chains everywhere, junk food being cheaper and easier than healthy food to get, junk food loaded with addictive chemicals that gives your brain a response similar to taking drugs, food loaded with hormones that makes you gain weight faster and lose it slower, etc.

Also as more medications are developed for things more folks are on medications in general, and a side effect of a number of medications happens to be weight gain.

There are many reasons. But generally, if you're an American, unless you like to cook and regularly make time for it, you are probably going to be overweight, unless you are very active, which most Americans are not.

Actually, that's a very complicated, convoluted thing to explain.

Caveats:
Politically-charged
Greed and Avarice-centric
Religious Debauchery has a hand in it
Technology is a crutch

I'll only explain further if one thing is kept.
I WANT NO BACKLASH FOR EXPLAINING IT. NONE.

Life is too easy these days.

Lack of self control,laziness...

I'm not fat